Endangered and Threatened Wildlife and Plants; Endangered Status for the Island Marble Butterfly and Designation of Critical Habitat, 26786-26820 [2020-07856]
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Federal Register / Vol. 85, No. 87 / Tuesday, May 5, 2020 / Rules and Regulations
Brad
Thompson, Acting State Supervisor,
Washington Fish and Wildlife Office,
510 Desmond Drive, Suite 102, Lacey,
WA 98503; telephone 360–753–9440.
Persons who use a telecommunications
device for the deaf (TDD) may call the
Federal Relay Service at 800–877–8339.
SUPPLEMENTARY INFORMATION:
FOR FURTHER INFORMATION CONTACT:
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS–R1–ES–2016–0145;
FF09E21000 FXES11110900000 201]
RIN 1018–BB96
Endangered and Threatened Wildlife
and Plants; Endangered Status for the
Island Marble Butterfly and
Designation of Critical Habitat
Fish and Wildlife Service,
Interior.
ACTION: Final rule.
AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), determine
endangered species status under the
Endangered Species Act of 1973 (Act),
as amended, for the island marble
butterfly (Euchloe ausonides insulanus)
and designate critical habitat. In total,
approximately 812 acres (329 hectares)
on the south end of San Juan Island, San
Juan County, Washington, fall within
the boundaries of the critical habitat
designation.
DATES: This rule is effective June 4,
2020.
ADDRESSES: This final rule is available
on the internet at https://
www.regulations.gov. Comments and
materials we received, as well as
supporting documentation we used in
preparing this rule, are available for
public inspection at https://
www.regulations.gov at Docket No.
FWS–R1–ES–2016–0145. Comments,
materials, and documentation that we
considered in this rulemaking will be
available by appointment, during
normal business hours at: U.S. Fish and
Wildlife Service, Washington Fish and
Wildlife Office, 510 Desmond Drive,
Suite 102, Lacey, WA 98503; telephone
360–753–9440.
The coordinates or plot points or both
from which the maps are generated are
included in the administrative record
for this critical habitat designation and
are available at https://
www.regulations.gov at Docket No.
FWS–R1–ES–2016–0145, on the
Service’s website at https://
www.fws.gov/wafwo/,and at the
Washington Fish and Wildlife Office
(address provided above). Any
additional tools or supporting
information that we developed for this
critical habitat designation will also be
available at the Fish and Wildlife
Service website and Field Office set out
above, and may also be included in the
preamble and at https://
www.regulations.gov.
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SUMMARY:
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Executive Summary
Why we need to publish a rule. Under
the Endangered Species Act, a species
may warrant protection through listing
if it is endangered or threatened
throughout all or a significant portion of
its range. Listing a species as an
endangered or threatened species can
only be completed by issuing a rule.
Further, under the Endangered Species
Act, any species that is determined to be
an endangered or threatened species
requires critical habitat to be designated,
to the maximum extent prudent and
determinable. Designations and
revisions of critical habitat can only be
completed by issuing a rule.
What this document does. This rule
lists the island marble butterfly
(Euchloe ausonides insulanus) as an
endangered species and designates
critical habitat for this species under the
Endangered Species Act. We are
designating critical habitat for the
species in one unit, on public and
private property totaling 812 acres (329
hectares) on San Juan Island, San Juan
County, Washington.
The basis for our action. Under the
Endangered Species Act, we can
determine that a species is an
endangered or threatened species based
on any of five factors: (A) The present
or threatened destruction, modification,
or curtailment of its habitat or range; (B)
overutilization for commercial,
recreational, scientific, or educational
purposes; (C) disease or predation; (D)
the inadequacy of existing regulatory
mechanisms; or (E) other natural or
manmade factors affecting its continued
existence. We have determined that the
island marble butterfly faces the
following threats:
• Habitat loss and degradation from
plant succession and invasion by plants
that displace larval host plants;
browsing by black-tailed deer, European
rabbits, and brown garden snails; and
storm surges;
• Predation by native spiders and
nonnative wasps, and incidental
predation by black-tailed deer; and
• Vulnerabilities associated with
small population size and
environmental and demographic
stochasticity, and other chance events
that increase mortality or reduce
reproductive success.
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Existing regulatory mechanisms and
conservation efforts do not address
these threats to the island marble
butterfly to the extent that listing is not
warranted.
This rule also designates critical
habitat for the island marble butterfly in
accordance with the Endangered
Species Act. The critical habitat areas
we are designating in this rule
constitute our current best assessment of
the areas that meet the definition of
critical habitat for the island marble
butterfly.
Economic analysis. We prepared an
economic analysis of the impacts of
designating critical habitat. We made
the draft economic analysis available for
public comments on April 12, 2018 (83
FR 15900). The analysis found no
significant economic impact of the
designation of critical habitat.
Peer review and public comment. We
sought comments from five independent
specialists to ensure that our species
determination and critical habitat
designation are based on scientifically
sound data, assumptions, and analyses.
We obtained opinions from two
knowledgeable individuals with
scientific expertise to review our
technical assumptions and analysis, and
whether or not we had used the best
scientific data available. These peer
reviewers generally concurred with our
methods and conclusions, and provided
additional information, clarification,
and suggestions to improve this final
rule. Information we received from peer
review is incorporated into this final
rule. We also considered all comments
and information we received from the
public during the comment period for
the proposed listing and the proposed
designation of critical habitat.
Previous Federal Actions
On April 12, 2018, we published in
the Federal Register a proposed rule (83
FR 15900) to list the island marble
butterfly as an endangered species and
to designate critical habitat for the
species under the Endangered Species
Act of 1973 (Act), as amended (16
U.S.C. 1531 et seq.). Please refer to that
proposed rule for a detailed description
of Federal actions concerning the island
marble butterfly that occurred prior to
the proposal’s publication.
Summary of Changes From the
Proposed Rule
Based on information we received
from peer reviewers and public
commenters, in this rule, we make the
following changes from our April 12,
2018, proposed rule (83 FR 15900):
(1) We describe habitat use by the
island marble butterfly to better reflect
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that the organism exhibits ‘‘patchy’’
population dynamics at the local scale
rather than following a classic
metapopulation dynamic model;
(2) We indicate that the island marble
butterfly has been observed flying on
lands immediately adjacent to the
American Camp unit of San Juan Island
National Historical Park (SJINHP);
(3) We update portions of the rule to
reflect the most current information
regarding captive rearing and
monitoring;
(4) We indicate that while female
island marble butterflies tend to use a
single host plant species in each of three
specific habitat types, there are
instances (for example, when host
plants are scarce) when they will use
another of the three known host plant
species in a specific habitat type;
(5) We revise the description of the
time that island marble butterflies spend
as winged adults from an estimated
average of 6 to 9 days to include the
potential to persist as winged adults for
up to 16 days, based on documentation
provided by two separate commenters;
(6) We include information regarding
the aversion male island marble
butterflies have demonstrated for flying
over tall vegetation, including avoiding
flying over fields of tall grasses; and
(7) We revise the critical habitat
discussion and designation to address
the limitations in the precision of
mapped critical habitat, to clarify that
the critical habitat designation includes
road shoulders and road margins, and to
clarify our intent to designate as critical
habitat only the steep coastal bluffs on
private lands near Eagle Cove.
Summary of Comments and
Recommendations
In our April 12, 2018, proposed rule
(83 FR 15900), we requested that all
interested parties submit written
comments on the proposal by June 11,
2018. We also contacted appropriate
Federal and State agencies, scientific
experts and organizations, and other
interested parties and invited them to
comment on the proposed
determination, proposed designation of
critical habitat, and draft economic
analysis. Newspaper notices inviting
general public comment were published
in the Islands’ Sounder, Journal of the
San Juans, and the Seattle Times. We
did not receive any requests for a public
hearing. All substantive information
provided during the comment period
has either been incorporated directly
into this final rule or is addressed
below.
During the comment period, we
received 23 comment letters addressing
the proposed determination and/or the
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proposed critical habitat designation.
We address all substantive comments
either below or by making the requested
changes to the rule, as described above,
when we determined that they were
correct. We did not receive comments
from any Federal agencies or Tribes. We
received a letter of support from the
Washington Department of Fish and
Wildlife; however, their letter did not
contain any comments or requests for
revision of the language.
Peer Reviewer Comments
In accordance with our peer review
policy published on July 1, 1994 (59 FR
34270), we solicited expert opinion
from five knowledgeable individuals
with scientific expertise that included
familiarity with the island marble
butterfly and its habitat, biological
needs, and threats; the geographic
region in which the species occurs; and
conservation biology principles. We
received responses from two of the peer
reviewers.
We reviewed all comments we
received from the peer reviewers for
substantive issues and new information
regarding the island marble butterfly
and its critical habitat. The peer
reviewers generally concurred with our
methods and conclusions, and provided
additional information, clarifications,
and suggestions to improve the final
rule. Peer reviewer comments are
addressed in the following summary
and incorporated into the final rule as
appropriate.
(1) Comment: One peer reviewer
highlighted the lack of clarity
surrounding what constitutes a ‘‘site,’’
both within American Camp and
outside of the park.
Our Response: Due to the way data
were collected and submitted to the
Service, we were limited in the way we
could reference and analyze detection or
nondetection of the island marble
butterfly in any given year. We assign
the term ‘‘site’’ to each location that has
a name and survey information
associated with it.
(2) Comment: One peer reviewer
indicated that describing the island
marble butterfly as having a ‘‘low
dispersal capacity’’ was inaccurate and
suggested revising the narrative to
reflect that the island marble butterfly
exhibits ‘‘patchy population dynamics.’’
Our Response: We revised the
narrative in this rule to reflect that the
island marble butterfly generally
exhibits weak site fidelity and low to
intermediate dispersal capacity, which
are key behavioral components of
patchy population dynamics.
(3) Comment: One peer reviewer and
one commenter identified potential
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suitable habitat for the island marble
butterfly in areas known to be
previously occupied and stated that
these areas should be included in
critical habitat.
Our Response: We considered all
previously occupied areas in the
analysis of proposed critical habitat. For
the reasons stated below under Areas
Occupied at the Time of Listing, we are
designating critical habitat only on and
around American Camp. We are unable,
at this time, to delineate any specific
unoccupied areas that are essential to
the conservation of the island marble
butterfly due to the ephemeral and
patchy nature of the species’ habitat and
our limited understanding regarding the
ideal configuration of habitat, the ideal
size and number of habitat patches, and
how these habitat patches may naturally
evolve on the landscape. This does not
mean that other areas are not important
or valuable to the recovery of the island
marble butterfly, or that we only need
one occupied unit to recover the
species.
Public Comments
(4) Comment: One commenter posited
that the decline and disappearance of
the island marble butterfly was caused,
in part, by the decline in traditional
harvest of food resources by preEuropean peoples who inhabited the
Gulf Islands and the San Juan
archipelago followed by the
introduction and establishment of
nonnative weedy plant species.
Our Response: While these factors
may have contributed to the decline of
the island marble butterfly and other
disturbance-dependent native butterfly
species, we were unable to locate any
substantiating evidence that would
support this claim.
Background
Species Information
Taxonomy and Species Description
The island marble butterfly (Euchloe
ausonides insulanus) is a subspecies of
the large marble butterfly (E. ausonides)
in the Pieridae family, subfamily
Pierinae, which primarily consists of
yellow and white butterflies. The island
marble butterfly was formally described
in 2001, by Guppy and Shepard (p. 160)
based on 14 specimens collected
between 1859 and 1908 on or near
Vancouver Island, British Columbia,
Canada, and is geographically isolated
from all other E. ausonides subspecies.
The taxonomic status of the island
marble butterfly is not in dispute.
Euchloe ausonides insulanus is
recognized as a valid subspecies by the
Integrated Taxonomic Information
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System (ITIS 2015a, entire) based on the
phenotypic differences documented in
Guppy and Shepard (2001). In this rule,
we use shorthand for simplicity in
referring to the island marble butterfly
as a species because subspecies are
treated as species for the purposes of
evaluating taxa for listing under the Act.
Island marble butterflies have a
wingspan of approximately 1.75 inches
(in) (4.5 centimeters (cm)) (Pyle 2002, p.
142) and are differentiated from other
subspecies of the large marble butterfly
by their larger size and the expanded
marbling pattern of yellow and green on
the underside of the hindwings and
forewings (Guppy and Shepard 2001, p.
159). Immature stages of the island
marble butterfly have distinctly
different coloration and markings from
Euchloe ausonides; specifically, the
third and fourth larval instars (instars
are the larval stages between molting
events) have a white spiracular stripe (a
stripe that runs along the side of a
caterpillar) subtended (bordered below)
by a yellow-green subspiracular stripe
and a green-yellow ventral area, which
is different from the stripe colors and
patterns described for E. ausonides
(James and Nunnallee 2011, pp. 102–
103; Lambert 2011, p. 15). The island
marble butterfly is also behaviorally
distinct; large marble butterflies pupate
(enter the final stage of larval
development before transforming into a
butterfly) directly on their larval host
plants, whereas the island marble
butterflies leave their host plants to find
a suitable pupation site up to 13 feet (ft)
(4 meters (m)) away from their larval
host plants (Lambert 2011, p. 19).
Distribution
The island marble butterfly was
historically known from just two areas
along the southeastern coast of
Vancouver Island, British Columbia,
Canada, based on 14 museum records:
The Greater Victoria area at the southern
end of Vancouver Island; and near
Nanaimo and on adjacent Gabriola
Island, approximately 56 miles (mi) (90
kilometers (km)) north of Victoria. The
last known specimen of the island
marble butterfly from Canada was
collected in 1908 on Gabriola Island,
and the species is now considered
extirpated from the province (COSEWIC
2010, p. 6). Reasons for its
disappearance from Canada are
unknown. Hypotheses include
increased parasitoid loads (the number
of individual deadly parasites within an
individual caterpillar) associated with
the introduction of the cabbage white
butterfly (Guppy and Shepard 2001, p.
38) or heavy grazing of natural meadows
by cattle and sheep, which severely
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depressed its presumed larval food
plant (SARA 2015).
After 90 years without a documented
occurrence, the island marble butterfly
was rediscovered in 1998 on San Juan
Island, San Juan County, Washington, at
least 9 mi (15 km) east of Victoria across
the Haro Strait. Subsequent surveys in
suitable habitat across southeastern
Vancouver Island and the Gulf Islands
in Canada (see COSEWIC 2010, p. 5), as
well as the San Juan Islands and six
adjacent counties in the United States
(Whatcom, Skagit, Snohomish,
Jefferson, Clallam, and Island Counties),
revealed only two other occupied areas.
One of these occupied areas was
centered on San Juan Island and the
other on Lopez Island, which is
separated from San Juan Island by just
over 0.5 mi (1 km) at its closest point.
These occupied areas were eventually
determined to comprise five
populations, as described in detail in
our 2006 12-month finding (71 FR
66292; November 14, 2006). Since 2006,
the number and distribution of
populations has declined. Four of the
five populations that once spanned San
Juan and Lopez Islands have not been
detected in recent years, and the species
is now observed only in a single area
centered on American Camp, a part of
San Juan Island National Historical Park
that is managed by the National Park
Service (NPS). The island marble
butterfly has also been sighted using the
lands adjoining or near American Camp;
there were observations of island marble
butterflies flying beyond the boundaries
of these adjoining lands in 2015 and
2017 (Potter 2015a, in litt.; Lambert
2018, in litt.).
No current records exist of any lifehistory stage of the island marble
butterfly except at or near American
Camp at San Juan Island National
Historical Park. Therefore, we consider
only American Camp and the
immediately adjacent areas to be
occupied at the time of this final listing.
Survey Effort
Extensive surveys have been
conducted in British Columbia, Canada,
since 2001, with an estimated 500
survey hours conducted by professional
surveyors and 2,000 survey hours by
volunteer butterfly enthusiasts
(COSEWIC 2010, p. v). During these
surveys, neither the island marble
butterfly nor suitable habitat was
detected (COSEWIC 2010, p. vi). The
species has been considered extirpated
in British Columbia since 1910, and was
formally designated extirpated in 1999
by the Canadian government (COSEWIC
2000, p. iii).
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In the United States, surveys for the
island marble butterfly have also been
extensive. In 2005 and 2006, we
partnered with NPS, Washington
Department of Fish and Wildlife
(WDFW), Washington Department of
Natural Resources (WDNR), the
University of Washington, and the
Xerces Society to survey for the
presence of the island marble butterfly
during the adult flight period (when
eggs are laid and larvae are active; early
April–late June). Qualified surveyors
conducted approximately 335
individual surveys at more than 160
sites in potentially suitable habitat
across 6 counties (Clallam, Jefferson,
Island, San Juan, Skagit, and Whatcom
Counties) and on 16 islands (Miskelly
and Potter 2005, pp. 5, 7–16; Miskelly
and Fleckenstein 2007, pp. 4, 10–19).
Outside of American Camp, sites were
defined primarily by ownership,
although some exceptionally large sites
were subdivided and received unique
site names. All surveys followed a set of
standardized protocols to ensure they
were conducted when butterflies had
the highest likelihood of being detected
(see Miskelly and Potter 2005, p. 4).
Island marble butterflies were
considered present at sites where eggs,
larvae, or adults of the species were
detected. These surveys documented
five populations distributed across San
Juan and Lopez Islands, including the
single population persisting today
centered on American Camp (Miskelly
and Fleckenstein 2007, pp. 4–5).
Annual surveys conducted outside of
American Camp from 2007–2012
focused on areas with suitable habitat
on San Juan and Lopez Islands. These
surveys generally included previously
occupied sites, when accessible, in
order to document whether or not island
marble butterflies persisted at the sites
where they were detected in 2005 and
2006. After years of observing a
rangewide decline in available island
marble butterfly habitat and dwindling
island marble butterfly detections,
WDFW determined that there was not
enough suitable habitat remaining
outside of American Camp to warrant
continued widespread survey efforts on
San Juan and Lopez Islands. Therefore,
surveys in 2013 and 2014 focused solely
on assisting with monitoring at
American Camp and surveying lands
directly adjacent to the park (Potter
2015a in litt.). Surveys to monitor the
status of the population centered on
American Camp have been conducted
annually from 2004 to 2015, although
the effort has varied through time (see
‘‘Abundance,’’ below, for additional
information).
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In 2015, in addition to annual
population monitoring at American
Camp, the Service funded an extensive
survey of sites on San Juan Island
outside of American Camp. Areas
surveyed included those sites where
island marble butterflies had previously
been detected, as well as areas with
suitable habitat with no prior
detections. Researchers conducted 134
individual surveys at a total of 48 sites,
including 24 sites where the island
marble butterfly had been documented
previously. The survey yielded no
detections of the island marble butterfly
outside of American Camp.
Multiple years of extensive surveys
conducted across formerly occupied
sites have failed to detect the species.
However, it is possible that the island
marble butterfly continues to exist at a
handful of small isolated sites where
surveyors were not granted access or
were unable to survey during suitable
conditions (Miskelly and Potter 2005,
entire; Miskelly and Fleckenstein 2007,
entire; Miskelly and Potter 2009, entire;
Hanson et al. 2009, entire; Hanson et al.
2010, entire; Potter et al. 2011, entire;
Vernon and Weaver 2012, entire;
Weaver and Vernon 2014, entire; Potter
2015a in litt.; Vernon 2015a, entire).
Abundance
In our 2006 12-month finding, we
estimated the abundance of island
marble butterflies to be ‘‘probably less
than 500 butterflies, and possibly as low
as 300 individuals’’ (71 FR 66292,
November 14, 2006, p. 66295). These
numbers were based on limited data,
and their accuracy is uncertain. Since
2006, there have been several efforts to
either directly estimate population size
or evaluate changes in relative
abundance through time (described
below). In addition, captive-rearing and
release of butterflies was initiated in
2013, and as of the spring of 2018, over
500 captive-raised butterflies have been
released at American Camp to
supplement the population (SJINHP
2018, in litt.) (see the discussions of
conservation efforts under Factors A
and C, below, for more details).
Site Occupancy—The number of sites
where the island marble butterfly is
detected each year is a useful indicator
of coarse-scale changes in abundance.
The island marble butterfly has been
recorded at a total of 63 individual sites
since rangewide surveys began in 2005:
The species was found at 37 sites in and
around American Camp and 26 sites
outside of American Camp (Miskelly
and Potter 2005, pp. 7–14; Miskelly and
Fleckenstein 2007, pp. 14–19; Miskelly
and Potter 2009, pp. 7–8, 10–11; Hanson
et al. 2009, pp. 10–11, 24–28; Hanson et
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al. 2010, pp. 12–13, 26–30; Potter et al.
2011, pp. 10–23, 15–23; Potter 2012,
unpublished; Potter 2013, unpublished;
Vernon and Weaver 2012, pp. 4–7;
Weaver and Vernon 2014, pp. 5–8). The
number of occupied sites recorded at
American Camp is somewhat
confounded by changes in survey
methods and effort through time (see
‘‘Survey Effort,’’ above). We recognize
this as a potential source of uncertainty,
but note that both transect data and
anecdotal observations suggest a
population decline at American Camp
since monitoring began in 2004 (see
Transect Counts, below).
The largest number of concurrently
occupied sites reported was 25 in 2007,
10 of which were outside of American
Camp (Miskelly and Potter 2009, pp. 7–
8, 10–11; Potter et al. 2011, pp. 15–16).
The number of occupied sites declined
every year from 2007 to 2011, with the
species detected at only seven sites in
2011, only one of which was outside of
American Camp. In 2015, adult island
marble butterflies were detected at only
four of the regularly monitored sites at
American Camp, the fewest occupied
sites ever recorded, and no adults, eggs,
or larvae were detected outside of the
greater American Camp area (Potter
2015a in litt.; NPS 2015, entire; Vernon
2015b, entire), although there were two
observations of single adult butterflies
flying just beyond the boundary of the
park that were not recorded in formal
surveys by NPS (Potter 2015a, in litt.).
Island marble butterflies were detected
as eggs in six additional research plots
at American Camp (Lambert 2015d, p.
4), but none of the eggs tracked in the
research plots survived to the fifth larval
instar (Lambert 2015d, p. 13). In 2016
and 2017, larval habitat for the island
marble butterfly at American Camp
increased substantially, and
survivorship of individuals tracked from
eggs through fifth instar larvae increased
from zero in 2015 to 3 percent in 2016
(Lambert 2016a, pp. 10, 21), but
decreased to 1 percent in 2017, the last
year for which survivorship data were
collected (Lambert 2017, pp. 3, 12).
The reasons for the precipitous
decline in the number of occupied sites
since 2005 are not known with
certainty, but the near-complete loss of
habitat outside of American Camp in
some years is likely a principal cause.
Habitat loss has been caused by road
maintenance, mowing, cultivation of
land, intentional removal of host plants,
improperly timed restoration activities,
development, landscaping, deer browse,
and livestock grazing (Miskelly and
Potter 2005, p. 6; Miskelly and
Fleckenstein 2007, p. 6; Miskelly and
Potter 2009, p. 9; Hanson et al. 2009, p.
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18; Hanson et al. 2010, p. 21; Potter et
al. 2011, p. 13).
Transect Counts—Counts along
transects can provide a measure of
relative abundance, which can be useful
in assessing changes in the population
among sites and through time (Peterson
2010, pp. 12–13). From 2004 to 2008,
Lambert (2009) counted adult island
marble butterflies along transects at
American Camp (14 established in 2004,
and an additional 2 (for a total of 16)
established in 2005), finding a
consistent and significant decline in the
number of adults observed: They
counted 270 in 2004, 194 in 2005, 125
in 2006, 71 in 2007, and 63 in 2008
(Lambert 2009, p. 5). These raw counts
were also translated to relative
encounter rates that account for
differences in survey effort across years,
and these encounter rates also showed
a marked decline until 2016 (USFWS
2016). Four of these transects were
monitored by NPS almost continuously
from 2004 to 2016 (one transect was not
monitored from 2009 to 2011), and
relative encounter rates were calculated
that accounted for transect length and
the number of times the transect was
surveyed each year. The relative
encounter rate on these transects
declined substantially between 2004
and 2015, from almost 2 butterflies per
100 meters surveyed in 2004, to
approximately 0.3 butterflies per 100
meters in 2015 (USFWS 2016). Survey
results for 2016 improved across the
three transects consistently monitored at
American Camp, with approximately
0.6 butterflies per 100 meters. While an
observation of 0.6 butterflies per 100
meters reflects an improvement from
recent years, this improvement does not
reverse the overall decline observed
since monitoring began in 2004. The
Service has not received updated
transect data for the flight seasons of
2017 or 2018.
Mark-Release-Recapture—Markrelease-recapture (MRR) studies were
conducted at American Camp in 2008
and 2009 (and at one additional site on
San Juan Island—the Pear Point Gravel
Quarry, which is no longer occupied)
(Peterson 2009, 2010, entire). These
studies sought to address several
demographic questions and to assess
whether transect counts were a reliable
method to estimate changes in the
population through time (Peterson 2009,
p. 3). MRR population estimates were
generated for three focal areas at
American Camp in 2009: The western
end of American Camp (an estimated 50
individuals), American Camp below the
Redoubt (an estimated 39 individuals),
and the dunes at American Camp (an
estimated 24 individuals). However,
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because American Camp was not
surveyed in its entirety, these areas
represent an unquantified fraction of the
occupied habitat at American Camp;
therefore, we cannot extrapolate from
this information to estimate the
rangewide population.
In summary, monitoring efforts have
varied since 2008, but reports from NPS
indicate an ongoing decrease in the
relative abundance of the island marble
butterfly at American Camp, suggesting
that total numbers continue to decline
(Vernon and Weaver 2012, pp. 5–6;
Weaver and Vernon 2014, p. 6). While
reliable and precise rangewide
population estimates have not been
produced for this species, the available
evidence suggests that the species has a
very small population that has declined
substantially since monitoring began in
2004.
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Habitat
The island marble butterfly has three
known host plants, all in the mustard
family (Brassicaceae). One is native,
Lepidium virginicum var. menziesii
(Menzies’ pepperweed), and two are
nonnative: Brassica rapa (no agreedupon common name, but sometimes
called field mustard; hereafter referred
to as field mustard for the purposes of
this document) (ITIS 2015b, entire), and
Sisymbrium altissimum L. (tumble
mustard) (Miskelly 2004, pp. 33, 38;
Lambert 2011, p. 2).
All three larval host plants occur in
open grass- and forb-dominated
vegetation systems, but each species is
most robust in one of three specific
habitat types: Menzies’ pepperweed at
the edge of low-lying coastal lagoon
habitat; field mustard in upland prairie
habitat, disturbed fields, and disturbed
soils, including soil piles from
construction; and tumble mustard in
sand dune habitat (Miskelly 2004, p. 33;
Lambert 2011, pp. 24, 121–123). While
each larval host plant can occur in the
other habitat types, female island
marble butterflies tend to select specific
host plants in each of the three habitat
types referenced above, likely because
certain host plants are more robust in
each habitat type during the flight
season (Miskelly 2004, p. 33; Lambert
2011, pp. 24, 41, 50, 54–57, 121–123;
Shrum 2018, in litt.). Host plants that
establish and grow outside of their
primary habitat type typically are less
robust, and female butterflies do not
appear to choose them preferentially but
may use them when other larval habitat
is limited (Lambert 2011, pp. 24, 41, 50,
54–57, 121–123; Shrum 2018, in litt.).
Adults primarily nectar (forage) on
their larval host plants (Potter 2015e,
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pers. comm.), but use a variety of other
nectar plants including:
• Abronia latifolia (yellow sand
verbena),
• Achillea millefolium (yarrow),
• Amsinckia menziesii (smallflowered fiddleneck),
• Cakile edentula (American sea
rocket),
• Cerastium arvense (field
chickweed),
• Erodium cicutarium (common
stork’s bill),
• Geranium molle (dovefoot
geranium),
• Hypochaeris radicata (hairy cat’s
ear),
• Lomatium utriculatum (common
lomatium),
• Lupinus littoralis (seashore lupine),
• Myosotis discolor (common forgetme-not),
• Ranunculus californicus (California
buttercup),
• Rubus ursinus (trailing blackberry),
• Taraxacum officinale (dandelion),
• Toxicoscordion venenosum (death
camas, formerly known as Zigadenus
venenosus), and
• Triteleia grandiflora (Howell’s
brodiaea, formerly Brodiaea howellii)
(Miskelly 2004, p. 33; Pyle 2004, pp.
23–26, 33; Miskelly and Potter 2005, p.
6; Lambert 2011, p. 120; Vernon and
Weaver 2012, appendix 12; Lambert
2015a, p. 2, Lambert 2015b, in litt.). Of
these additional nectar resources, island
marble butterflies are most frequently
observed feeding on yellow sand
verbena, small-flowered fiddleneck, and
field chickweed (Potter 2015e, pers.
comm.). Adults primarily use lowstatured, white flowering plants such as
field chickweed as mating sites
(Lambert 2014b, p. 17).
Biology
The island marble butterfly life cycle
comprises four distinct developmental
phases: Egg, larva, chrysalis, and
butterfly. Development from egg to
chrysalis takes approximately 38 days
and includes five instars (phases of
larval development between molts)
(Lambert 2011, p. 7). Female island
marble butterflies produce a single
brood per year, and prefer to lay their
eggs individually on the unopened
terminal flower buds of their larval host
plants (Lambert 2011, pp. 9, 48, 51).
Gravid female butterflies appear to
select plants with many tightly grouped
flower buds over host plants with fewer
buds, and they tend to avoid laying eggs
on inflorescences (flower heads) where
other island marble butterflies already
have deposited eggs (Lambert 2011, p.
51). However, the number of eggs laid
on a single host plant has been observed
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to vary with the density and distribution
of host plants and may also be affected
by host plant robustness as well as the
age of the individual female butterfly
(Parker and Courtney 1984, entire;
Lambert 2011, pp. 9, 53, 54).
First instar larvae are able to feed only
on tender portions of the host plant,
such as developing flower buds and
new growth, and initially move no more
than a few centimeters from where they
hatch before they must feed; thus, larvae
that hatch from eggs located more than
a few centimeters from a host plant’s
flower heads often starve before
reaching a suitable food source (Lambert
2011, pp. 12–13). The limited
locomotion of newly hatched larvae and
their reliance on tender flower buds as
a food resource leads to a concentration
of early-instar larvae near the tips of
their larval host plants (Lambert 2011,
p. 13). Larvae become more mobile in
later instars, and their better developed
mouthparts allow them to consume
older, tougher plant material.
Eventually, they may move to stems of
other nearby host plants to forage
(Lambert 2011, pp. 15–17).
The fifth (last) instar larvae ‘‘wander’’
through standing vegetation, never
touching the ground, as they search for
a suitable site on which to pupate (form
a chrysalis) (Lambert 2011, p. 20). The
greatest distance a fifth instar larva has
been observed to move from its final
larval host plant was 4 meters, but few
observations exist (Lambert 2011, p. 19).
Fifth instar larvae select slender dry
stems in the lower canopy of moderately
dense vegetation as sites for pupation
and entering diapause, a state of
suspended development (Lambert 2011,
p. 21).
Island marble butterflies spend the
largest portion of their annual life cycle
in diapause as chrysalids. They enter
diapause in midsummer and emerge as
butterflies in the spring of the following
year. One island marble chrysalis
remained in diapause for 334 days (11
months) (Lambert 2011, p. 22).
Extremely low survivorship at early lifehistory stages has been found in recent
years (e.g., of 136 and 226 individual
eggs tracked in 2014 and 2015,
respectively, zero survived to pupation;
Lambert 2015d, p. 13).
Adult island marble butterflies
emerge from early April to mid-June and
live as winged adults for up to 16 days
(Peterson 2009, p. 7; Peterson 2018, in
litt.; Vernon 2018, in litt.), with most
persisting for a much shorter period;
estimates range from 2 to 9 days
(Lambert 2011, pp. 50, 180; Peterson
2009, p. 7).
Males emerge 4 to 7 days before
females and patrol hillsides in search of
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mates (Lambert 2011, p. 47). Male island
marble butterflies have been observed to
prefer low-statured vegetation, generally
avoiding flight over expanses of tall
grasses (Miskelly 2018, in litt.). Male
island marble butterflies are attracted to
white (ultraviolet-reflecting) objects that
may resemble females and have been
observed to investigate white flowers
(e.g., field chickweed and yarrow),
white picket fences, and white lines
painted on the surface of roads (Lambert
2011, p. 47). When a male locates a
receptive female, mating may occur
hundreds of meters from the nearest
larval host plant, increasing the
potential extent of adult habitat to
include a varied array of plants and
vegetative structure (Lambert 2011, p.
48). Individual adult island marble
butterflies seldom disperse distances
greater than 0.4 mi (0.6 km), with the
greatest documented dispersal distance
being 1.2 mi (1.9 km) (Peterson 2010,
pp. 3, 12).
Island marble butterflies generally
exhibit weak site fidelity and low to
intermediate dispersal capacity. When
considered rangewide, the island marble
butterfly exists as a group of spatially
separated populations that interact
when individual members move from
one occupied location to another
(Miskelly and Potter 2009, p. 14;
Lambert 2011, p. 147). For the island
marble butterfly, a population is defined
as a group of occupied sites close
enough for routine genetic exchange
between individuals. Thus, occupied
areas separated by distances greater than
3 mi (4.8 km) with no intervening
suitable habitat and a low likelihood of
genetic exchange are considered to be
separate populations (Miskelly and
Potter 2009, p. 12). Five potential
populations of island marble butterflies
were identified and described in detail
in the 2006 12-month finding (71 FR
66292, November 14, 2006, p. 66294):
American Camp and vicinity, San Juan
Valley, Northwest San Juan Island,
Central Lopez Island, and West Central
Lopez Island. As described previously,
only the population at American Camp
has been detected since 2012.
Summary of Factors Affecting the
Species
Section 4 of the Act (16 U.S.C. 1533)
and its implementing regulations in title
50 of the Code of Federal Regulations
(50 CFR part 424) set forth the
procedures for determining whether a
species is an endangered species or
threatened species. The Act defines an
endangered species as ‘‘in danger of
extinction throughout all or a significant
portion of its range,’’ and a threatened
species as ‘‘likely to become an
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endangered species within the
foreseeable future throughout all or a
significant portion of its range.’’ Section
4(a)(1) requires the Secretary to
determine whether a species is an
endangered species or threatened
species because of any of the following
five factors: (A) The present or
threatened destruction, modification, or
curtailment of its habitat or range; (B)
overutilization for commercial,
recreational, scientific, or educational
purposes; (C) disease or predation; (D)
the inadequacy of existing regulatory
mechanisms; or (E) other natural or
manmade factors affecting its continued
existence.
To inform the determination, we
complete a status assessment in relation
to the five factors using the best
available scientific and commercial
data. The status assessment provides a
thorough description and analysis of the
stressors, regulatory mechanisms, and
conservation efforts affecting
individuals, populations, and the
species. We use the terms ‘‘stressor’’ and
‘‘threat’’ interchangeably, along with
other similar terms, to describe anything
that may have a negative effect on the
island marble butterfly. In considering
what factors might constitute threats, we
must look beyond the mere exposure of
the species to the factor to determine
whether the species responds to the
factor in a way that causes actual
impacts to the species. If there is
exposure to a factor, but no response, or
only a positive response, that factor is
not a threat. The mere identification of
threats that could affect the island
marble butterfly is not sufficient to
compel a finding that listing is
appropriate. Rather, we evaluate the
effects of the threats in light of the
exposure, timing, and scale of the
threats, both individually and
cumulatively, and any existing
regulatory mechanisms or conservation
efforts that may ameliorate or exacerbate
the threats in order to determine if the
species meets the definition of an
endangered species or threatened
species.
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Since we first analyzed stressors to
the island marble butterfly’s habitat on
San Juan and Lopez Islands in 2006, the
species’ distribution has contracted, and
it is now known only from American
Camp and the immediate vicinity on
San Juan (see ‘‘Distribution,’’ above).
Island marble butterfly larval habitat in
natural landscapes, such as that found
at American Camp, is patchy at best,
making it difficult to estimate the
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acreage of larval host plants.
Additionally, larval host plants are early
successional species that thrive in
disturbed habitats. This can result in
larval habitat patches that may be
present one year and gone the next,
depending on the level of disturbance
present on the landscape.
Development
Residential development occurs on
both San Juan and Lopez Islands,
primarily on private lands. Habitat loss
from development affects the island
marble butterfly by reducing the
availability of secure habitat that will
persist long enough for the island
marble butterfly to complete its life
cycle. Development may also affect the
known occupied range of the island
marble butterfly by constraining the
amount of stepping-stone habitat
(patches of habitat too small to maintain
an established population, but large
enough to allow for connectivity
between larger suitable patches) for
dispersal. In addition, mowing or
removal of host plants (e.g., for
landscaping around developments) may
also remove island marble butterfly
habitat or prevent its establishment.
Because female island marble butterflies
selectively lay their eggs on the
inflorescences (flowering head) of tall,
robust plants (Lambert 2011, p. 55),
mowing host plants reduces the
availability of suitable oviposition (egg
laying) sites for the island marble
butterfly.
Within American Camp, which is
protected by NPS regulations (see Factor
D discussion, below), development is
not a threat to the island marble
butterfly. However, residential
development was a threat to island
marble butterfly habitat in the Cattle
Point Estate and Eagle Cove
developments adjacent to American
Camp. These areas accounted for 199 ac
(81 ha) of island marble butterfly
habitat, or 18 percent of occupied
habitat in 2006, which are now
unoccupied due to habitat loss (Potter
2015a, in litt.) associated with
development (e.g., mowing,
landscaping, or removal of host plants)
(Miskelly and Potter 2005, p. 6; Miskelly
and Fleckenstein 2007, p. 6; Hanson et
al. 2009, p. 9).
In 2006, we noted that development
was occurring less rapidly in the areas
to the north and west of American Camp
and on Lopez Island where lands
comprised small, rural farms with
pastures and low-density residential
properties. We concluded that these
areas, containing about 361 ac (146 ha),
or 32 percent of the occupied habitat as
of 2006, would be managed in a way
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that was compatible with island marble
butterfly habitat. Since that time, the
amount of farmland in San Juan County
has decreased, with the greatest loss of
farmland in San Juan County attributed
to the subdivision of larger farms into
smaller parcels, which have then been
developed (San Juan County
Agricultural Resources Committee 2011,
p. 23). While there are no estimates of
the amount of potential habitat for the
island marble butterfly lost specifically
to development, habitat loss outside of
American Camp from a variety of
sources has been substantial (Miskelly
and Potter 2005, p. 6; Miskelly and
Fleckenstein 2007, p. 6; Miskelly and
Potter 2009, p. 9; Hanson et al. 2009, pp.
18–19; Potter et al. 2011, pp. 13–14;
Potter 2015a, in litt.). In addition to
development of former agricultural
lands, perhaps more significant are the
management practices on these lands
that effectively preclude recolonization
by island marble butterflies or create
population sinks (habitat patches that
attract dispersing individuals, but do
not allow them to complete their life
cycle and reproduce) (see ‘‘Agricultural
Practices,’’ below). We conclude that
development has substantively
contributed to the extirpation of the
island marble butterfly outside of
American Camp and remains one of
several factors impeding successful
recolonization of previously occupied
habitats; however, because American
Camp is protected from development by
NPS regulations and is where the
species solely occurs, development is
not a threat currently acting on the
remaining extant population of the
species.
Road Construction
In our 2006 12-month finding (71 FR
66292; November 14, 2006), we
evaluated the impact of a planned road
relocation project (Cattle Point Road
relocation project) through American
Camp. Cattle Point Road is the only
point of access for residents at the
southeastern tip of San Juan Island and
traverses the slope of Mount Finlayson,
effectively bisecting occupied island
marble butterfly habitat at the park. We
estimated that the relocation would
cause temporary loss of as much as 13
ac (5 ha) of island marble butterfly
habitat due to clearing and removal of
larval host plants, although there was no
known breeding habitat along the
highway at that time. We concluded that
the road realignment was likely to
proceed with little mortality to the
island marble butterfly.
Since 2006, we have worked closely
with NPS and the Federal Highway
Administration (FHA) to ensure that
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project impacts were avoided or
minimized. Once the project began, in
2015, the Service, NPS, and WDFW
actively surveyed the road alignment to
remove host plants before they could
attract oviposition by female island
marble butterflies and to rescue island
marble butterfly eggs and larva from any
larval host plants that might have been
overlooked. Island marble butterfly
larval habitat in natural landscapes,
such as that found at American Camp,
is patchy at best, making it difficult to
estimate the acreage of larval host
plants. While the area affected by road
construction was estimated to be 13 ac
(5 ha), larval host plants did not occur
in dense patches across the construction
site. As a result of these efforts, far less
suitable habitat for island marble
butterflies was temporarily lost than we
anticipated in 2006, and impacts to the
island marble butterfly population were
significantly reduced and potentially
completely avoided.
Habitat restoration will continue for
several years; once it is completed, we
anticipate that the project will be a net
benefit to the quantity and quality of
island marble butterfly habitat in the
project area due to early coordination
with the FHA and the proactive
conservation measures they
implemented throughout the process.
These conservation measures included
the proactive removal of all larval host
plants from the footprint of the project
described above (so that butterflies do
not lay eggs on plants bound to be
destroyed) and the reseeding of larval
and nectar host plant species in the
disturbed areas. These measures will
both increase the quantity and improve
the quality of the habitat surrounding
the finished project. In conclusion, road
construction is not currently a threat to
the island marble butterfly.
Road Maintenance
Road maintenance that destroys or
negatively affects island marble
butterfly larval host plants has been a
concern since 2005, when it was
documented as destroying occupied
larval habitat on both San Juan and
Lopez Islands (Miskelly and Potter
2005, p. 6). For example, in 2005, at
Fisherman’s Bay tombolo (a narrow
beach landform that connects the
mainland to an island) on Lopez Island,
road maintenance crews deposited a
quantity of sand on occupied larval host
plants in an effort to reduce the fire
hazard of the vegetation in preparation
for a Fourth of July fireworks display. In
addition to the deposition of sand on
occupied habitat, the remainder of the
site was mowed by road maintenance
crews, removing all remaining larval
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host plants. There were no detections of
the island marble butterfly in 2006, a
single detection at the tombolo in 2007,
and none through 2015 (Miskelly and
Potter 2009, p. 21; Potter et al. 2011, p.
16; Potter 2015a, in litt.).
Roadside maintenance has resulted in
the destruction of suitable habitat on
Lopez Island and outside of American
Camp on San Juan Island (Miskelly and
Potter 2005, p. 6). Despite changes in
roadside maintenance practices to
address habitat loss, these protections
were not implemented uniformly
throughout San Juan County, nor were
they implemented with the immediacy
necessary to allow for widespread
persistence of island marble habitat
along roadsides (Potter 2016, pers.
comm.). However, because roadside
maintenance at American Camp will be
conducted in close coordination with
the Service, we conclude that whereas
habitat loss associated with road
maintenance activities could be one of
several factors impeding successful
recolonization of previously occupied
habitats, it likely will have only minor
impacts on the island marble butterfly,
given its current distribution. We do not
expect these impacts to change within
American Camp in the future.
Vegetation Management
The island marble butterfly is present
year round and largely stationary while
in its early developmental phases,
becoming most visible when it becomes
a winged adult. The cryptic egg, larval,
and chrysalis forms make island marble
butterflies vulnerable to land
management and restoration practices
when those practices overlap occupied
areas. For example, in 2005, NPS
conducted a prescribed fire intended to
restore native prairie, and this fire
burned through the occupied habitat
during the butterfly’s developmental
stage and likely killed all eggs and
larvae within the affected area.
Similarly, the use of herbicides for the
purpose of vegetation restoration in
occupied island marble butterfly habitat
has been documented (Potter et al. 2011,
p. 14). Although the direct effects of
herbicides on island marble butterflies
have not been studied, indiscriminate
application of herbicides in areas
occupied by eggs or larvae is likely to
result in mortality through elimination
of larval host plants and primary food
resources.
Since 2010, the Service, NPS, WDFW,
and other partners have cooperated
closely to achieve vegetation
management and restoration goals while
also conserving the island marble
butterfly and its habitat, including
nonnative larval host plants. As a result,
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vegetation management has not resulted
in significant harm to island marble
butterflies since 2010. The island
marble butterfly is vulnerable to
vegetation management or restoration
practices that are improperly timed or
poorly sited. However, this vulnerability
does not, by itself, result in impacts to
the species. Currently, vegetation
management does not have a significant
impact on the species because the
ongoing collaboration between
cooperating partners has adequately
minimized the impacts of vegetation
management actions at American Camp.
Agricultural Practices
Agricultural activities that include
tilling of the soil have been identified as
a stressor for the island marble butterfly
(Potter et al. 2011, p. 14). Removal or
destruction of habitat by conversion
from an agricultural condition that
provides suitable habitat (e.g., old field
pasture) for island marble butterfly to an
agricultural condition that does not
allow the island marble butterfly to
complete its life cycle (e.g., active
cropping) has likely led to the decline
of occupied island marble butterfly
habitat outside of American Camp and
continues to contribute to the
curtailment of the former range of the
species. The species has not been
detected since 2012 at any previously
occupied agricultural sites that have
been surveyed (Potter et al. 2011, pp.
15–16; Potter 2012, unpublished data;
Potter 2013, unpublished data; Vernon
2015b in litt., entire). In addition, no
new occupied sites in agricultural areas
have been detected during surveys
conducted in 2015 (Vernon 2015a,
entire).
Practices on San Juan and Lopez
Islands that require tilling the soil, such
as grain farming, can promote growth of
field mustard (a host plant) during the
island marble butterfly’s flight period if
tilling takes place during fall and winter
months (e.g., December through
February), allowing field mustard seeds
in the seed bank to germinate and
mature in synchrony with the needs of
the island marble butterfly. Because
cereal crops compete with field
mustard, the array of established plants
can result in a diffuse number of larval
host plants at a density attractive to
female island marble butterflies
searching for an oviposition site. When
actively cropped agricultural areas with
larval host plants occur near occupied
habitat, they can create an ‘‘ecological
trap’’ if dispersing females lay eggs
where the larvae do not have adequate
time to complete their life cycle before
the crop is harvested and the site is
tilled for replanting the following spring
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(Hanson et al. 2009, pp. 18–19; Miskelly
and Potter 2009, p. 14).
Similarly, grazing can produce an
ecological trap if females lay eggs in
suitable habitat that is then consumed
by livestock (see Herbivory by livestock,
below). However, since the 1980s,
farming on San Juan Island has trended
toward small market gardens, and large,
livestock-based farms have been
reduced in number (San Juan County
Agricultural Resources Committee 2011,
p. 16). Livestock grazing does not
currently overlap any areas known to be
occupied by the island marble butterfly;
thus, livestock grazing is not currently
a threat to the island marble butterfly,
although it could become a threat in the
future if the island marble butterfly
were to become reestablished in areas
where grazing takes place. The best
available scientific and commercial
information does not indicate that
agricultural practices currently affect
the island marble butterfly because the
known population occurs on NPS lands
that are not managed for agricultural
use.
Plant Succession and Competition With
Invasive Species
All of the known larval host plants for
the island marble butterfly are annual
mustard species that are dependent on
open, early-successional conditions for
germination (Lambert 2011, p. 149).
Disturbance or active management
maintains these conditions; otherwise,
plant succession and invasion by weedy
native and nonnative plants greatly
inhibit germination and growth of larval
host plants. These processes of
vegetation change thus degrade and
reduce the availability of habitat
required by the island marble butterfly
to complete its life cycle.
Succession of open, low-statured
vegetation to woody plants is a natural
process in the absence of anthropogenic
burning or other forms of disturbance.
The cessation of Native American
burning in the mid-1800s resulted in the
loss of prairie habitat in western
Washington, including the San Juan
archipelago, due to tree and shrub
encroachment (Hamman et al. 2011, p.
317). Prairies were repeatedly burned
during historical times by Native
Americans for a variety of reasons, and
areas used for cultivation of food plants,
such as Camassia leichtlinii or C.
quamash (great camas and common
camas, respectively), may have been
burned on an annual basis (Beckwith
2004, pp. 54–55; Boyd 1999, entire;
Chappell and Kagan 2001, p. 42).
Early estimates of the size of the
prairie at American Camp suggest it may
have been as large as 1,500 acres (ac)
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(607 hectares (ha)) when the first
Europeans arrived (Douglas 1853,
entire). Today, the prairie is estimated
to be 695 ac (281 ha) due, in part, to
succession and encroachment of
Douglas-fir trees (Pseudotsuga
menziesii) and other woody vegetation
(Rochefort et al. 2012, p. 9). Reclaiming
and maintaining open prairie habitat at
American Camp requires active
management to control Douglas fir trees
and other woody species (Rochefort et
al. 2012, p. 4).
Two of the three known larval hosts
for the island marble butterfly are
introduced species that self-propagate
into open, disturbed areas: Field
mustard and tumble mustard. In the
absence of active restoration or
disturbance, other weedy plant species,
as well as woody plants and trees, are
likely to colonize the site, eventually
outcompeting the early-successional
host plants. At American Camp, where
remnant prairie habitat persists, weedy
species such as Elymus repens (quack
grass), Holcus lanatus (velvet grass),
Cirsium arvense (Canada thistle), and
Vicia sativa (common vetch), among
others, outcompete the larval host
plants in the absence of disturbance.
Competition with nonnative species
also affects host plants in sand dune
habitat. The sand dunes represent a
unique habitat type for the island
marble butterfly that includes open,
shifting sands easily colonized by the
larval host plant, tumble mustard
(Lambert 2011, p. 42). While Menzies’
pepperweed and field mustard also
occasionally occur in dune habitat,
tumble mustard is the host plant that
occurs there most commonly, is most
robust in this habitat type, and can
create continuous stands of larval host
plants under optimal conditions
(Lambert 2011, pp. 42, 65). When
nonnative species such as Canada
thistle, hairy cat’s ear, and Rumex
acetosella (sheep sorrel) colonize the
sandy dune habitat, the dunes become
increasingly stable and the effect is a
reduction in the available germination
sites for tumble mustard (Weaver and
Vernon 2014, pp. 5, 9). Canada thistle
has the greatest potential to negatively
affect dune habitat where it is
stabilizing the sand and facilitating
establishment of grasses, which, in turn,
displace tumble mustard (Rochefort
2010, p. 28; Weaver and Vernon 2014,
p. 9).
Conditions for larval host plants
continue to be degraded through plant
succession and invasion throughout the
range of the island marble butterfly.
Loss of habitat conditions favorable for
larval host plants, and thus habitat loss
for the island marble butterfly, occurs in
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at least two of three habitat types at
American Camp, the only area where
the island marble butterfly is currently
known to persist (Weaver and Vernon
2014, pp. 5, 9). Loss of potentially
suitable but not currently occupied
habitat resulting from succession also
occurs in any areas outside of American
Camp where these processes take place.
Due to the extremely limited numbers
and range of the island marble butterfly,
any further loss of habitat may lead to
further decline of the species and
preclude its establishment in new areas.
Herbivory
Herbivory by deer: Black-tailed deer
(Odocoileus hemionus columbianus) are
common in the San Juan Island
archipelago. At the single occupied site
where island marble butterfly is
currently known to exist, black-tailed
deer numbers appear to be increasing
(Lambert 2014a, p. 3). Browsing deer
prefer flowering plants when available,
and tend to select stems on the tops or
sides of plants over the stems that
emerge lower on the stalk (Anderson
1994; p. 107; Lambert 2015c, in litt.,
Thomas 2015, pers. obs.). Specifically,
at study sites where island marble
butterflies exist, deer browse selectively
on robust larval host plants with several
inflorescences of compact flower buds—
the same plant characteristics preferred
by female island marble butterflies as
egg-laying sites (Lambert 2011, p. 103).
The effect of deer browsing on larval
host plants is three-fold. First, it
destroys suitable egg-laying habitat;
second, it stimulates rapid growth of
lateral (side) stems on the plant,
rendering the plant less likely to
support an individual butterfly from egg
to late-instar larva; and third, continual
browsing of the flowering portion of the
plant reduces seed production, resulting
in fewer larval host plants over time
(Lambert 2011, p. 10; Lambert 2014a, p.
10; Lambert 2015d, p. 17). Deer
browsing, which stimulates rapid lateral
stem growth, results in increased
mortality when eggs are laid on the
flowers of lateral stems on the larval
host plants (Lambert 2011, p. 10).
Immobile, early-instar larvae of island
marble butterfly present on these stems
are left behind as the stems grow away
from them. When the larvae can no
longer access the tender tissues at the
developing tips of the plant that they
require for survival, they die from
starvation (Lambert 2011, p. 10, Lambert
2015e, in litt.).
The destructive effects of deer
browsing on larval habitat are common
where surveys have taken place
throughout the known range of the
island marble butterfly (Miskelly and
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Fleckenstein 2007, p. 6; Miskelly and
Potter 2009, pp. 11, 15; Hanson et al.
2009, pp. 4, 13, 19–20; Hanson et al.
2010, pp. 21–22; Potter et al. 2011, pp.
5, 13; Lambert 2011, p. 104; Lambert
2014a, entire; Weaver and Vernon 2014,
p. 10; Vernon and Weaver 2012, p. 9;
Lambert 2015d, pp. 17–18). At
American Camp, herbivory by deer has
affected 95 percent of field mustard
plants in some years (Lambert 2011, p.
127). Deer exclusion fencing has been
erected to protect suitable habitat at
American Camp to counteract the
impacts of deer browsing, but the
fencing has not been fully effective at
excluding deer, and deer have
continued to consume occupied larval
host plants (see ‘‘Habitat Conservation
and Restoration,’’ below).
Habitat loss attributable to herbivory
by deer is ongoing and extensive
throughout the current and former range
of the island marble butterfly, and may
be increasing, with substantial impacts
to the species (Lambert 2011, pp. 85–
104; Lambert 2014a, p. 3; Lambert
2015d, pp. 14–18). The effect of habitat
loss due to deer herbivory is
compounded by the effect of inadvertent
predation when the larval host plants
are occupied by eggs or larvae (see
‘‘Incidental Predation’’ under the Factor
C discussion, below).
Herbivory by livestock: Livestock
readily consume field mustard, which is
often cultivated in pastures as a way to
improve forage for cows and sheep
(Smart et al. 2004, p. 1; McCartney et al.
2009, p. 436). There is no livestock
grazing at American Camp, but livestock
pastures are present on San Juan and
Lopez Islands in areas that may contain
suitable habitat for dispersing island
marble butterflies. When cattle or sheep
are present on lands where field
mustard is grown, they readily consume
the flower heads, stems, and stalk of the
plant, destroying suitable island marble
butterfly habitat (Miskelly and Potter
2009, p. 15; Hanson et al. 2009, p. 20;
Hanson et al. 2010, p. 21). Like
conversion of old field pastures to active
cropping, cultivation of field mustard as
a forage species for livestock potentially
creates an ecological trap for the island
marble butterfly when cultivation takes
place within dispersal distance of an
occupied site, and female island marble
butterflies lay eggs in a patch of field
mustard that is later consumed or
trampled by livestock before any larvae
can complete their life cycle (see
‘‘Incidental Predation’’ under Factor C,
below, for further discussion). In
conclusion, loss of potential habitat to
livestock grazing can prevent
reestablishment and persistence of
suitable habitat for the species outside
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of American Camp. However, because
livestock grazing is not allowed on
American Camp where the species
occurs, herbivory by livestock is not a
threat currently acting on the remaining
population of the species.
Herbivory by rabbits: The European
rabbit, Oryctolagus cuniculus, is a
common invasive species in the San
Juan Islands (Hall 1977, entire; Burke
Museum 2015). At American Camp,
European rabbits have been established
for more than a century, following their
introduction to San Juan Island during
the late 1800s (Couch 1929, p. 336).
Grazing by European rabbits, when they
proliferate, affects both vegetative
structure and composition, reducing
both the number and kind of plant
species near their warrens (network of
burrows) (Eldridge and Myers 2001, pp.
329, 335). Herbivory by European
rabbits negatively affects the
recruitment and establishment of larval
host plants; where rabbits occur at
American Camp, few larval host plants
for the island marble butterfly persist
due to the intense grazing pressure
(Radmer 2015, in litt.). When larval host
plants do germinate near European
rabbit warrens, they are consumed
before the plants are large enough for
female island marble butterflies to
recognize and use them.
Population monitoring of European
rabbits has been conducted at American
Camp from 1985 to 2015, documenting
an estimated population high of
approximately 1,750 rabbits in 2006,
and a low of fewer than 100 in 2012.
From 2009 through 2012, the population
was estimated to be 100 animals or
fewer, and the condition of vegetation in
the affected area had ‘‘changed
dramatically’’ with the reduction in
rabbit grazing pressure (West 2013, pp.
2, 4). The most recent population
estimate, in 2015, was approximately
500 animals, indicating that the rabbit
population at American Camp is
currently on the rise (West 2015, in litt.).
If European rabbits remain uncontrolled
at American Camp, their population is
likely to fluctuate but continue
expanding overall in the next decade,
similar to the patterns documented in
the past 30 years of monitoring data.
The majority of the European rabbit
population has been, and may continue
to be, centered on a single large field
near the middle of American Camp,
surrounded by areas that include island
marble butterfly habitat. As their
population grows, we expect the
impacts of European rabbits to expand,
encroaching upon and destroying
additional island marble butterfly
habitat.
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Herbivory by brown garden snails:
The nonnative brown garden snail
(Cornu aspersum, formerly Helix
aspersa) is a generalist herbivore that
has been reported to occur in great
numbers in some areas where island
marble butterfly previously occurred
(e.g., Pear Point Gravel Pit or ‘La Farge’
and San Juan Valley), where it feeds on
field mustard and tumble mustard, the
two most common larval host plants for
the island marble butterfly (Hanson et
al. 2010, p. 18; Potter et al. 2011, p. 13).
State biologists removed hundreds of
snails that were feeding on larval host
plants at Pear Point in 2010, when the
island marble butterfly still occupied
this site (Potter et al. 2011, p. 13). The
brown garden snail has extremely high
reproductive potential; it matures
within 2 years and can produce more
than 100 eggs five or six times each year
(Vernon 2015c, p. 1). The number of
brown garden snails observed on San
Juan Island has increased substantially
between the years of 2009 and 2015
(Potter et al. 2011, p. 13; Vernon 2015c
in litt., entire).
In 2015, the brown garden snail was
observed in San Juan Valley, a site
formerly occupied by the island marble
butterfly, and in 2016, the brown garden
snail was documented in the South
Beach area at American Camp by a
Service biologist (Vernon 2015c in litt.,
entire; Vernon 2015a p. 4; Reagan 2016,
pers. obs.). High numbers of brown
garden snails have been documented in
highly disturbed sites previously
occupied by island marble butterfly, and
since our 2016 12-month finding (81 FR
19527; April 5, 2016) was published,
they have been found invading the
natural areas in American Camp
currently occupied by the island marble
butterfly and its host plants (Shrum
2017, in litt.). This most recent
development indicates that brown
garden snail is now well established
within American Camp and the habitat
currently used by the island marble
butterfly, raising the likelihood that
herbivory by the brown garden snail
will result in habitat loss or degradation
to an extent that can affect the
butterfly’s survival and reproductive
success. While there are no documented
accounts of snails directly consuming
island marble butterfly eggs or larvae,
the brown garden snail poses a threat to
the island marble butterfly by
consuming larval host plants, whether
those plants are occupied or not.
Therefore, herbivory by brown garden
snails is detrimental to the butterfly’s
overall survival and reproductive
success because it can both reduce the
quantity of suitable host plants available
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and cause incidental mortality of
individuals.
Storm Surges
The nearshore lagoon habitat for
island marble butterfly is close to sea
level. Three intermittently occupied
sites are in lagoons along the
northeastern edge of American Camp,
where they are partially protected from
tidal surges that arrive from the west.
One of these lagoons had the highest
relative encounter rate of all monitored
transects at American Camp in 2015,
and raw counts at this site represented
roughly 50 percent of the adult island
marble butterflies recorded during
annual monitoring for that year. Storm
surges, attributable to the combined
forces of high tides and high-wind storm
events, inundate these low-lying lagoon
areas intermittently, as evidenced by the
deposition of driftwood logs along the
shoreline. These events have occurred
with some regularity through time, but
the most recent episodes of inundation
have been particularly destructive of
nearshore island marble butterfly
habitat. A storm surge event in the
winter of 2006 resulted in the
deposition of gravel substrate and
driftwood over an island marble
butterfly research plot where the one
native larval host plant, Menzies’
pepperweed, had been established,
reducing the number of plants by more
than 50 percent (Lambert 2011, pp. 145–
146). This same storm surge likely
destroyed any butterflies that were
overwintering in nearshore habitat as
chrysalids and had a local populationlevel impact; low numbers of individual
island marble butterflies, eggs, and
larvae were detected at the site for
several years following the event
(Lambert 2011, p. 99; Lambert 2015f, in
litt.).
The frequency of storm surges large
enough to inundate the lagoons and
destroy island marble butterfly habitat
has previously been relatively low, but
since 2006, at least one storm surge
event (in 2009) was strong enough to
inundate the low-lying habitat
(Whitman and MacLennan 2015, in
litt.). The frequency of these events is
expected to increase with sea-level rise
associated with climate change (see
Factor E discussion, below). In turn, we
anticipate a concomitant increase in the
potential for destruction of low-lying
habitat for the island marble butterfly—
approximately 15 to 20 percent of the
species’ habitat in American Camp
(Lambert 2011, p. 145; Adeslman et al.
2012, pp. 79–86; Whitman and
MacLennan 2015, in litt.; NOAA 2015a,
entire; NOAA 2015b, entire).
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The Menzies’ pepperweed (the native
host plant) occurs almost exclusively in
the low-lying nearshore habitat, and
female island marble butterflies have
been observed to deposit eggs on only
a single species of larval host plant at
any one site. (Despite close observations
of ovipositing females, researchers have
not observed females depositing eggs on
more than one type of larval host plant
at any one site.) Therefore, if this habitat
type is lost, an unknown proportion of
diversity—in habitat use or adaptive
potential—in the island marble butterfly
could be lost as well. Furthermore, lowlying habitat comprises an estimated 15
to 20 percent of habitat for the species
at American Camp, a considerable
proportion of the restricted range of the
species. Due to the small size of the
remaining known population of the
island marble butterfly and the
importance of this low-lying habitat
demonstrated by high encounter rates
during surveys, loss or degradation of
this habitat will likely lead to a further
decline of the species.
Habitat Conservation and Restoration
San Juan Island National Historical
Park has been implementing
conservation measures for the island
marble butterfly since shortly after its
rediscovery in 1998. From 2003 through
2006, NPS created experimental prairie
disturbances and vegetation plots to
better understand how to manage the
prairie and create island marble
butterfly habitat. This work resulted in
recommendations for the best method of
reducing the cover of invasive grasses
by using prescribed fire followed by
herbicide treatment (Lambert 2006, p.
110). However, the work was not
reproduced at larger scales, nor was it
continued in ways sufficient to maintain
adequate habitat on the landscape over
time.
In 2018, we renewed a conservation
agreement with NPS for the island
marble butterfly that contained several
conservation actions that will be
applied to manage habitat for the
species into the future. The renewed
agreement, which was signed in
December 2018, committed NPS to: (1)
Restore, where needed, habitat for
island marble butterfly, as jointly
agreed; and (2) avoid impacts to island
marble butterflies, eggs, larvae, and host
plants during the implementation of all
NPS management actions by working in
habitat that was not occupied by island
marble butterflies. All vegetation
treatment will be conducted in the fall
after the island marble butterfly has
entered diapause. We expect the history
of collaborative conservation of the
island marble butterfly by NPS and the
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Service to continue for the foreseeable
future.
From 2007 through 2011, NPS
managed encroaching plant species
using multiple methods to open up
areas where larval host plants could
naturally germinate from the seed bank
(NPS 2013, pp. 7–11). NPS also planted
more than 100,000 native grass plugs in
mechanically treated areas (NPS 2013,
p. 7), which improved the native
composition of the prairie grassland
features but did not result in increased
cover of the larval host plants needed to
support the island marble butterfly. The
Service continued to work
collaboratively with NPS to develop
annual work plans each year from 2013
through 2016; these work plans are
addenda to the 2006 conservation
agreement for the island marble
butterfly. The goals and actions
identified in the work plans have
changed, sometimes annually, in
response to new information, adaptive
management needs, available funding,
and other concerns. The 2013–2016
work plans identified and enacted
several conservation actions to address
threats related to the destruction,
modification, and curtailment of island
marble butterfly habitat at American
Camp. Prescribed fire, deer fencing of
essential habitat, management of
invasive species, and experimental
habitat restoration were all
implemented per annual work plans
during this period.
These work plans initially included
the use of prescribed fire in small blocks
(up to one acre) to disturb grassland
habitat in an effort to encourage larval
host plant patches to establish from the
seed bank. These prescribed fire events
resulted in very low germination of the
larval host plants, leading NPS to
conclude that few larval host plant
seeds persist in the seed bank. In
response, later annual work plans
recommended seeding the larval host
plant species after a prescribed burn.
The 2016 annual work plan also
included recommendations for the
development of novel methods for
creating island marble butterfly habitat.
In 2013, the Service funded the
installation of deer exclusion fencing at
American Camp in an effort to reduce
deer herbivory on larval host plants
(and the incidental consumption of eggs
and larvae; see discussion under Factor
E, below) and to increase suitable
oviposition sites. Deer fencing was
included in each year’s annual work
plan since 2013, and continues to be
employed as an exclusion technique.
Approximately 23 acres have been
fenced since deer exclusion efforts
began in 2013 (Shrum 2015a, in litt.).
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The various forms of deer exclusion
fencing that have been used have
resulted in mixed success in preventing
deer from consuming larval host plants.
For example, in 2015, electrified fencing
alone proved ineffective at excluding
deer at three of five research sites at
American Camp (Lambert 2015d, p. 17).
However, electric and wire-mesh
fencing combined have reduced deer
herbivory on larval host plants when
compared to years when exclusion
fencing was not employed (Lambert
2015d, p. 17). In one large expanse of
habitat at American Camp, the
distribution of field mustard was
essentially limited to the fenced areas in
2015, although environmental
conditions shifted substantively in
2016, allowing for a large flush of
persistent field mustard beyond the
fenced areas (Lambert 2014a, p. 23;
Lambert 2015a, p. 5; Lambert 2015d, p.
17; Lambert 2016a, p. 35). Despite these
challenges, deer exclusion fencing
remains an important tool for protecting
island marble butterfly habitat,
especially early in the flight season
when we expect survivorship to be the
highest (Lambert 2015d, p. 19). For
example, in 2016 (after the publication
of our 12-month finding on April 5,
2016 (81 FR 19527)), deer were
completely excluded from research sites
at American Camp for the first time,
resulting in one-quarter acre of restored
habitat for host plants, and increased
survival in island marble butterflies on
field mustard than in previous years
(Lambert 2016a, p. 11).
The annual work plans have also
included efforts to control weedy native
and nonnative species and encroaching
woody plants. Specifically, NPS has
removed hundreds of Douglas fir trees
and dozens of acres of Rubus
armeniacus (Himalayan blackberry), R.
laciniatus (blackberry), Symphoricarpos
albus (snowberry), and Crataegus
monogyna (one-seeded hawthorn) from
the American Camp prairie. These
actions have slowed the invasion of
native and nonnative species and
encroachment by woody plants and
have created early-successional
conditions that likely provided some
nectaring habitat for the island marble
butterfly. However, few larval host
plants germinated from the seed bank in
the areas cleared of encroaching plants.
Another area of focus under the work
plan for controlling invasive species is
herbicide treatment of Canada thistle in
the dunes.
NPS, in collaboration with the Service
and other partners, has supported
experimental research into the active
establishment of island marble butterfly
habitat since 2003. In 2014, an
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experimental approach for establishing
oviposition and larval habitat was
proposed. The Service, in coordination
with NPS, WDFW, and two local island
conservation organizations (San Juan
Preservation Trust (SJPT) and San Juan
County Land Bank (SJCLB)), developed
a plan to determine whether habitat
patches for the island marble butterfly
could be developed in a way that could
be scaled up efficiently in a landscape
context (Lambert 2014b, entire). Thirty
habitat patches were created on park
property at American Camp between
2014 and 2016, and 10 more will be
created in 2017 (Lambert 2016a, p. 59).
Early results from this work indicate
that habitat can be created quickly and
that island marble butterflies readily use
these patches for egg laying and larval
development if larval host plants
germinate in time to provide oviposition
sites for early-flying butterflies (Lambert
2015d, pp. 9–12).
Each year since 2013, NPS has
collected and reared a small number of
eggs and larvae in a captive-rearing
program (see discussion under Factor C,
below, for more information). In 2015,
the captive individuals emerged from
diapause much later than the wild
population. Despite the use of the
experimental plots for oviposition by
these late-flying, captive-reared females,
none of the eggs and larvae tracked in
the experimental plots survived. The
high mortality was attributed to
increased predation pressure by lateseason spiders and wasps (Lambert
2015d, p. 14) (see ‘‘Direct Predation’’
under Factor C, below). Results of
captive-rearing were better in 2016,
when captive-reared island marble
butterflies emerged in synchrony with
the wild population. Survivorship from
egg to fifth instar larvae was also higher
in the experimental plots in 2016; three
percent of the tracked larvae survived to
the fifth instar, which is a relatively
high survival rate for the island marble
butterfly.
The Service, in coordination with
NPS, supports habitat conservation
efforts by funding local conservation
groups to establish habitat patches on
three conserved sites across the former
range of the island marble butterfly.
Two of these experimental habitat
patches were established outside of
American Camp in 2015 and one in
2016. Each experimental patch has been
fully fenced to exclude herbivores
(primarily deer) and allow the larval
host plants to grow without herbivory
pressure (also see Factor C, ‘‘Incidental
Predation,’’ below).
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Education and Outreach
In 2009, the Service provided funding
to WDFW for the creation of a species
fact sheet and informational handout for
the public about the biology and
conservation needs of the island marble
butterfly. This pamphlet provided
outreach to interested parties and
increased the awareness of the public
about the decline of the island marble
butterfly. The pamphlet provided basic
information about how to protect and
support habitat essential to the island
marble butterfly. In 2011, the Service
collaborated with NPS, WDFW,
researchers from the University of
Washington, and the Center for Natural
Lands Management to reach out to the
community in a local Island Prairie
Educational Symposium to present
information on current approaches to
prairie management. Information gained
through years of prairie conservation
efforts in other northern and southern
Puget Sound prairie landscapes was
shared with the local island community.
Information about the island marble
butterfly and the educational materials
developed were well distributed within
the community; however, this effort did
not lead to the protection or restoration
of habitat adequate to ameliorate the
threat of habitat loss for the island
marble butterfly. Despite considerable
advances in habitat restoration, new
habitat establishment, captive rearing,
herbivore exclusion, and outreach and
education, the number of individual
island marble butterflies remains small
in the single remaining population.
Summary of Factor A
Habitat supporting the remaining
population at American Camp is
protected from development and
agriculture, but is exposed to the threats
of plant succession and invasive plant
species; herbivory by deer, rabbits, and
brown garden snails; and storm surges.
Habitat loss is likely a major factor
impeding the recolonization of areas
outside of American Camp. Outside of
American Camp, removal of larval host
plants by mowing; roadside
maintenance; road, residential, or urban
development; certain agricultural
practices (such as tilling, cropping, and
grazing); and landscaping activities has
substantially reduced the amount of
habitat available for recolonization by
the island marble butterfly either
temporarily (e.g., mowing, tilling,
cropping, or grazing) or permanently
(e.g., road, residential, and urban
development) since the island marble
butterfly was rediscovered (Miskelly
and Fleckenstein 2007, p. 6; Miskelly
and Potter 2009, p. 9; Hanson et al.
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2009, p. 18; Vernon 2015b in litt., p. 5).
This habitat removal is a primary factor
in the loss of all the remaining
populations of this species outside of
American Camp since 2006.
Since 2011, NPS has made substantial
and sustained efforts to expand island
marble butterfly habitat and to improve
the composition and structure of the
plant community to become more
suitable for the island marble butterfly.
Due to challenges in establishing
suitable habitat and protecting it from
the threats described above, only a few
acres of high-quality habitat for island
marble butterfly have been restored on
the American Camp landscape. Many
more acres within American Camp have
been improved by restoration actions or
protected from deer herbivory, but are
not yet considered high quality or fully
secure from herbivory by deer. To date,
these efforts may have resulted in a
small positive response in the island
marble butterfly population, as
evidenced by the 3 percent increase in
survivorship from the fourth to fifth
instar in 2016. However, the number of
those individuals that will successfully
pupate and emerge as winged adults in
the spring remains to be seen.
Conservation efforts by NPS have also
resulted in significant contributions to
our understanding of island marble
butterfly habitat and threats to that
habitat. Outside of American Camp, the
only conservation efforts that
specifically create habitat for the species
are the small island marble butterfly
habitat plots established by SJPT and
SJCLB. These efforts will be crucial to
establishing new populations of island
marble butterfly in the future, but the
achievement is too recent for their
effectiveness to be evaluated, especially
in the context of the extensive, ongoing
habitat loss from changing land use,
changing agricultural practices, and
other factors that inhibit recolonization
by island marble butterflies outside of
American Camp.
Despite successful habitat restoration
experiments, continued use of deer
exclusion fencing, and the removal of
woody plants and nonnative and native
weedy species, the increase in the total
area of currently suitable habitat within
American Camp has not been fully
quantified, although it remains small
(on the scale of quarters of acres).
Despite these minor gains in habitat as
a result of restoration since we
published our 12-month finding on
April 5, 2016 (81 FR 19527), the range
of the species—the number of sites
within American Camp where it is
observed—has continued to contract,
and the number of island marble
butterflies observed each year remains
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low. Conservation measures will need to
continue into the future, with
monitoring to assess their long-term
value to the island marble butterfly.
Until measureable changes to the island
marble butterfly population have been
documented, it will be difficult to
determine whether the implemented
measures are effecting positive change
in the status of the island marble
butterfly. Based on the analysis above,
we conclude that plant succession and
competition with invasive species,
herbivory by deer and brown garden
snails, and storm surges are likely to
have population-level impacts on the
island marble butterfly.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Overutilization for Commercial or
Recreational Purposes
Under NPS regulations, collection of
living or dead wildlife, fish, or plants,
or products thereof, is prohibited on
lands under the jurisdiction of NPS
without a permit (36 CFR 2.1(a)(1)(i)
and (a)(1)(ii)), but there are no State or
County regulations that prohibit
recreational collection of the island
marble butterfly at this time.
Rare butterflies and moths are highly
prized by collectors, and an
international trade exists in specimens
for both live and decorative markets, as
well as the specialist trade that supplies
researchers (Collins and Morris 1985,
pp. 155–179; Morris et al. 1991, pp.
332–334; Rieunier and Associates 2013,
entire). Before the island marble
butterfly was formally described,
collectors may have exerted little
pressure on the taxon because it was
unknown and because it occurs in
remote islands that had been littlesurveyed for butterflies. Following
formal description of the species in
2001, at least three inquiries about
potential for collection were made to
WDFW, which is responsible for
managing fish and wildlife in the State
of Washington, and one with NPS at
American Camp, which requires a
permit for the collection of any plant or
animal from park property (Reagan
2015, in litt.). WDFW has discouraged
collection, and NPS rejected the single
permit request for collection it received
(Reagan 2015, in litt.; Weaver 2015a, in
litt.). In addition to these permit
requests, we are aware of one specimen
of the island marble butterfly
purportedly being listed for sale on a
website devoted to trade in butterfly
species (Nagano 2015, pers. obs.),
although the origin and authenticity of
this specimen could not be verified.
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Even limited collection of butterfly
species with small populations could
have deleterious effects on the
reproductive success and genetic
variability within those populations and
could thus contribute eventually to
extinction or local extirpation (Singer
and Wedlake 1981, entire; Gall 1984,
entire). Capture and removal of females
dispersing from a population also can
reduce the probability that new
populations will be established or that
metapopulation structure will be
developed or maintained. (A
metapopulation is a group of spatially
separated populations that interact
when individual members move from
one population to another.) Collectors
pose a potential threat because they may
not be aware of other collection
activities, and are unlikely to know, and
may not care, whether or not they are
depleting numbers below the threshold
necessary for long-term persistence of
populations and the species (Martinez
1999, in litt.). This is especially true if
collectors lack adequate biological
training or if they visit a collection area
for only a short period of time (Collins
and Morris 1985, p. 165). In addition,
collectors often target adult individuals
in perfect condition, including females
that have not yet mated or had the
opportunity to lay all of their eggs.
Some collectors go to the length of
collecting butterfly eggs in order to rear
perfect specimens (USDOJ 1995, p. 2).
Collection of the island marble
butterfly, which is prohibited on NPS
lands, could potentially occur without
detection because occupied areas are
not continuously patrolled and adult
butterflies do move outside of protected
areas onto adjoining lands where
collection is not currently prohibited.
Consequently, the potential for
collection of adult island marble
butterflies, and especially surreptitious
collection of early stages (eggs, larvae,
and pupae) exists, and such collection
could go undetected, despite the
protection provided on NPS lands.
Taking into consideration the small
remaining population, illegal collection
could have strong detrimental effects on
the known population, were it to occur.
However, no illegal collection efforts for
this species have been documented to
date.
Scientific Overutilization
The widespread surveys that took
place in the period 2005–2012 included
capturing and releasing butterflies when
necessary for positive identification, as
specified in Miskelly and Fleckenstein
2007 (p. 4). Although a limited number
of individuals may have been injured or
killed during handling, no data exist on
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the number of individuals captured,
injured, or killed. To our knowledge,
there have been three documented
instances of island marble butterfly
collection or handling for scientific
purposes since the rediscovery of the
species. In 2005, two male specimens
were collected by WDFW surveyors as
vouchers to document newly discovered
island marble sites (Miskelly and Potter
2005, pp. 4, 5; Potter 2016, in litt.). In
2008, a mark-release-recapture (MRR)
study of the species’ demography
involved the capture and marking of 97
individual adult island marble
butterflies and recapture of 56
butterflies across four separate sites, and
some individuals were recaptured more
than once (Peterson 2009, entire;
Peterson 2010, entire). A single
individual butterfly was collected as a
voucher specimen under a WDFW
scientific collection permit in 2008 for
the MRR study (Potter 2016, in litt.). The
other scientific use of the island marble
butterfly of which the Service is aware
took place in 2013, when two adult
butterflies were collected by WDFW for
a genetic assessment of the island
marble butterfly, the results of which
were inconclusive (Potter 2015b, in
litt.).
The handling of adult butterflies for
scientific purposes has been evaluated
for effects on populations elsewhere in
western North America (Singer and
Wedlake 1981; Gall 1984). Murphy
(1988, p. 236) reported that MRR work
by others resulted in about 10 percent
mortality to the endangered mission
blue butterfly (Icaricia icarioides
missionensis); however, studies by
Singer and Wedlake (1981, entire) with
other butterflies resulted in less than 2
percent of the marked butterflies being
recaptured, suggesting that mortality
from handling the butterflies may have
been a factor.
Peterson’s 2008 MRR study may have
resulted in unintended injury or
mortality to island marble butterfly
individuals, but we have no evidence to
suggest that the study resulted in
population- or species-level effects.
Surveyors were unable to recapture 38
percent of the handled individuals
during the short duration of this
research, but whether this research
directly increased mortality for the
handled individuals is unknown.
Several outcomes could have led to this
low recapture rate: The butterflies may
have fully matured after completing
their life cycle and died during this
period; they may have been injured
during handling and died following
release; they may have become more
susceptible to other stressors after
handling (e.g., predation); or they may
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have simply eluded recapture. Based on
the relative encounter rate for the island
marble butterfly that was measured
during subsequent years (see
‘‘Abundance,’’ above, for additional
information), this research does not
appear to have contributed to a
constriction in the range of the species
or a decline in the abundance of
individuals.
The probability of numerous future
collections of live island marble
butterflies for research purposes is low
because all researchers who study the
island marble butterfly work
collaboratively with the Service, NPS,
and WDFW, and are aware of the very
low and declining number of individual
butterflies. Any research proposal
requiring the collection and removal of
live island marble butterflies from the
population is carefully reviewed to
determine whether the conservation
benefit to the species outweighs the loss
of individuals.
Summary of Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
We continue to find that
overutilization does not have a
population-level impact on the island
marble butterfly for the following
reasons: The lack of evidence of
commercial or recreational collection of
island marble butterflies; our conclusion
that handling of the species during the
2008 MRR study did not result in
documented negative effects to island
marble butterfly populations; and the
small number of individuals collected
for genetic evaluation.
Factor C. Disease or Predation
Disease
There is a single report of disease
affecting the island marble butterfly
(Miskelly 2004, p. 35). We discussed
this observation with the author and
discovered that this was an isolated
event and that the mortality was likely
attributable to causes other than disease
(Miskelly 2015a, in litt.). Therefore,
there is no evidence to suggest that
disease is currently a threat to the island
marble butterfly.
Direct Predation
Predation is a risk for island marble
butterflies during all stages of their life
cycle, although mortality is highest
during the earliest stages of life: Egg to
first instar (Lambert 2011, p. 92). A
study conducted from 2005 through
2008 on survivorship of the island
marble butterfly identified high levels of
mortality attributable to predation by
spiders and, to a lesser extent, paper
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wasps (Polistes spp.) (Lambert 2011, p.
117). Two species of spider, Pardosa
distincta and Zelotes puritanus, both
native to Washington State, prey on
adult island marble butterflies and may
also account for a large proportion of the
predation on eggs and larvae (Lambert
2011, p. 100; Crawford 2015, in litt.).
The paper wasp common to American
Camp is the nonnative Polistes
dominula (Miskelly 2015b, in litt.),
discovered in the State of Washington in
1998 (Landolt and Antonelli 1999,
entire).
Direct predation of eggs and larvae
was the greatest source of mortality in
this 4-year study, affecting 47 percent of
all individuals tracked (Lambert 2011,
p. 99). Mortality levels attributable to
direct predation varied depending on
the larval host plant used, with almost
80 percent mortality attributable to
direct predation on Menzies’
pepperweed and approximately 40
percent on field mustard (Lambert 2011,
p. 117). These differences are likely
attributable to variation in the structure
and growth form of the larval host
plants that can facilitate access by
predators (Lambert 2011, p. 100).
In addition, predation on island
marble butterfly larvae by spiders and
wasps increases as the season advances
(Lambert 2015d, p. 14). This increase is
likely because: (a) As spiders mature,
they are more effective at locating and
consuming the larvae; and (b) wasps
increase in number as the season
progresses (Reeve 1991, pp. 104–106),
and the predation pressure they exert on
their prey species increases with these
increased numbers. Later emergence of
island marble butterflies has been
observed to correlate closely with
increased predation pressure on island
marble larvae; in the 2015 field season,
when emergence was notably late, none
of the 329 individuals tracked from egg
through their larval development
survived to form a chrysalis (Lambert
2015d, p. 14) (see Cumulative Effects,
below, for additional discussion).
Predation on adult island marble
butterflies by birds and spiders has been
observed anecdotally, although no effort
has been made to quantify mortality
attributable to predation on adults
(Lambert 2011, p. 90; Vernon and
Weaver 2012, p. 10). We found no
evidence to suggest that predation by
small mammals or other vertebrate
predators presents a threat.
Direct predation of island marble
butterfly eggs and larvae is ongoing
where the species occurs (at American
Camp) and is expected to continue into
the future. Direct predation of eggs and
larvae is a significant cause of mortality
for the island marble butterfly,
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consistently accounting for more than
45 percent of deaths for tracked
individuals (Lambert 2011, p. 99;
Lambert 2015d, p. 14). Native spiders
are responsible for a significant
proportion of observed predation, and
the island marble butterfly presumably
coexisted for hundreds or thousands of
years with these spiders. However, the
small and declining numbers of island
marble butterflies, under pressure from
habitat loss and other threats, now
cannot tolerate what may once have
been a sustainable rate of natural
predation. The threat of direct predation
affects the island marble butterfly at the
individual, population, and species
levels (see Factor E discussion, below,
for more information).
Incidental Predation
Incidental predation by browsing
black-tailed deer also is a common
source of mortality for island marble
butterfly eggs and larvae (Lambert 2011,
pp. 93–97; Lambert 2015d, pp. 17–18).
As discussed above under Factor A,
female island marble butterflies select
oviposition sites on or near the tips of
the inflorescences of the larval host
plants, which is the same portion of the
plant that deer prefer to browse
(Lambert 2015c, in litt.). Similar to rates
of direct predation, each species of
larval host plant is correlated with
differing levels of mortality attributable
to deer browse. Incidental predation by
deer was highest on field mustard,
which accounted for slightly more than
40 percent of mortality tracked for this
larval host plant over the course of the
4-year study (Lambert 2011, p. 117).
Mortality attributable to deer browsing
was less than 10 percent for both
Menzies’ pepperweed and tumble
mustard (Lambert 2011, p. 117).
In nearly every report provided to the
Service, deer browsing has been
identified as particularly problematic
for the island marble butterfly at
American Camp as well as throughout
the species’ former range, where
browsing deer continue to degrade the
butterfly’s habitat (Miskelly and
Fleckenstein 2007, p. 6; Miskelly and
Potter 2009, pp. 11, 15; Hanson et al.
2009, pp. 4, 13, 20; Hanson et al. 2010,
pp. 21–22; Potter et al. 2011, pp. 5, 13;
Lambert 2011, p. 104; Lambert 2014a,
entire; Vernon and Weaver 2012, p. 9;
Weaver and Vernon 2014, p. 10;
Lambert 2014a, p. 3; Lambert 2015d, pp.
17–18; Vernon 2015a, p. 12). Incidental
predation by deer is a significant cause
of mortality of the island marble
butterfly at American Camp (Lambert
2014a, p. 3). Incidental predation by
deer is a threat of increasing severity
within American Camp, where it affects
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the island marble butterfly at the
individual, population, and species
level; outside American Camp, this
source of habitat degradation is ongoing
throughout the formerly occupied range
of the species because of the apparent
increase in deer numbers throughout the
San Juan Islands (Milner 2015, in litt.;
McCutchen 2016, in litt.).
Although incidental predation by
other herbivores has not been as
rigorously quantified as it has been for
black-tailed deer, the negative effects of
livestock on occupied larval host plants
cannot be discounted (Miskelly and
Fleckenstein 2007, p. 5; Miskelly and
Potter 2009, pp. 9, 11, 15; Hanson et al.
2009, pp. 18, 20; Hanson et al. 2010, pp.
5, 16, 21; Potter et al. 2011, p. 13;
Vernon 2015c in litt., entire). Incidental
predation by livestock, brown garden
snails, and European rabbits is possible
where the range of the island marble
butterfly overlaps with these species.
However, in the case of European
rabbits, only two documented instances
exist of rabbits consuming plants with
eggs or larva on them (Lambert 2015d,
p. 17). Suitable island marble butterfly
larval habitat is closely monitored at
American Camp, so while consumption
of occupied larval host plants by
European rabbits does occasionally take
place, it is currently rare, is
geographically circumscribed, and does
not have a population-level impact to
the species. The existing information
does not indicate that incidental
predation by livestock, brown garden
snails, and European rabbits is
occurring at a rate that currently causes
population-level impacts to the island
marble butterfly.
Conservation Efforts To Reduce Disease
or Predation
As described above under ‘‘Habitat
Conservation and Restoration,’’ the
Service and NPS installed deer
exclusion fencing in American Camp
from 2013 to 2016 to reduce browsing
by black-tailed deer on the larval host
plants field mustard and tumble
mustard. The fencing was placed to
reduce incidental predation, as well, by
protecting areas where larval host plants
are most likely to be occupied by island
marble butterfly eggs and larvae.
The Service has supported ongoing
research into the effects of deer
exclusion fencing on island marble
butterfly survival. The first deer
exclusion fencing was erected in three
locations of American Camp in 2013.
Areas immediately adjacent to the
fenced habitat with similar structure,
quality, and connectivity as the fenced
habitat were left unfenced as control
plots. First-year monitoring of deer
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exclusion areas showed that 74 percent
of eggs tracked survived to first instar in
the fenced area compared with 41
percent survival to first instar in the
control plots (Lambert 2014a, p. 6). In
2014, additional deer exclusion fencing
was installed, and different types of
exclusion fencing were compared. Wiremesh fencing was found to be effective
at preventing incidental predation by
deer, while electric fencing was
determined to be largely ineffective at
excluding deer, although mortality from
deer in electric-fenced areas was lower
than in previous years (Lambert 2015d,
pp. 17–18). Deer exclusion fencing has
emerged as an important tool for
protecting eggs and early instar larvae
from consumption by deer, especially
early in the flight season when
survivorship is expected to be the
highest (Lambert 2015d, p. 19; Lambert
2016a, pp. 3, 27).
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Summary of Disease and Predation
The best available information does
not indicate that disease is a threat to
the island marble butterfly. However, a
substantial amount of research
completed since 2006 clearly
documents the effects of predation.
Direct and incidental predation rates,
together, account for the vast majority of
the recorded deaths of island marble
butterfly eggs and larvae at American
Camp. Although deer exclusion fencing
at American Camp has been an
important tool for reducing mortality
due to incidental consumption since
2013, the number of island marble
butterflies observed continues to be low.
No conservation measures have yet been
identified to address the threat of
predation from paper wasps and
spiders. Taken together, all forms of
predation have pervasive, populationlevel impacts on the island marble
butterfly.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
ameliorate or exacerbate the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species . . . .’’ In
relation to Factor D under the Act, we
interpret this language to require the
Service to consider relevant Federal,
State, and tribal laws, regulations, and
other such mechanisms that may
ameliorate or exacerbate any of the
threats we describe in threat analyses
under the other four factors, or
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otherwise enhance conservation of the
species. We give strongest weight to
statutes and their implementing
regulations and to management
direction that stems from those laws and
regulations. An example would be State
governmental actions enforced under a
State statute or constitution, or Federal
action under statute.
Federal Laws and Regulations
American Camp, as part of San Juan
Island National Historical Park, is
managed under the National Park
Service’s Organic Act and implementing
regulations. The National Park Service
Organic Act of 1916, as amended (54
U.S.C. 100101 et seq.), states that the
National Park Service ‘‘shall promote
and regulate the use of the National Park
System . . . to conserve the scenery,
natural and historic objects, and wild
life in the System units and to provide
for the enjoyment of the scenery, natural
and historic objects, and wild life in
such manner and by such means as will
leave them unimpaired for the
enjoyment of future generations’’ (54
U.S.C. 100101(a)). Further, 36 CFR
2.1(a)(1)(i) and (a)(1)(ii) specifically
prohibit collection of living or dead
wildlife, fish, or plants, or parts or
products thereof, on lands under NPS
jurisdiction. This prohibition on
collection extends to the island marble
butterfly where it exists on NPSmanaged lands. In addition, under the
general management plan for San Juan
Island National Historical Park, NPS is
required to follow the elements of the
conservation agreement (NPS 2008, p.
73). This includes restoring native
grassland ecosystem components at
American Camp, avoiding management
actions that would destroy host plants,
avoiding vegetation treatments in island
marble butterfly habitat when early lifestages are likely to be present, and
implementing a monitoring plan for the
species (Pyle 2006, pp. 10–12).
The Bureau of Land Management
(BLM) owns the 27-ac (11-ha) Cattle
Point Lighthouse property east of
American Camp and Cattle Point
Natural Resource Conservation Area.
This site was formerly occupied by
island marble butterflies, is proximal to
occupied habitat on American Camp,
and contains suitable habitat for the
species. The Cattle Point Lighthouse
property is part of the San Juan Islands
National Monument established by
Presidential proclamation on March 25,
2013, under the American Antiquities
Act of 1906 (54 U.S.C. 320301 et seq.).
This proclamation specifically identifies
the island marble butterfly and states
that protection of the lands in the San
Juan Islands will maintain their
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historical and cultural significance and
enhance their unique and varied natural
and scientific resources, for the benefit
of all Americans. Under this
proclamation, the monument is being
managed as part of the National
Landscape Conservation System,
requiring that the land be managed ‘‘in
a manner that protects the values for
which the components of the system
were designated’’ (16 U.S.C. 7202(c)(2)).
The first resource management plan for
the National Monument is still in
development, so specific regulatory
protections for the species and its
habitat have not yet been established.
Nevertheless, anthropogenic threats at
this site are unlikely given its current
designation as a National Monument.
The island marble butterfly is also
listed as a sensitive species for the
purposes of the BLM’s Sensitive Species
Policy (BLM 2008, p. 3; USFS 2015,
entire). This policy directs the BLM to
initiate conservation measures that
reduce or eliminate threats and
minimize the likelihood of listing under
the Act, but until the resource
management plan for the National
Monument is complete, the BLM has
not identified the required conservation
measures. At this time, it is unclear
what protections, if any, these existing
regulatory mechanisms will confer to
the island marble butterfly.
State Laws and Regulations
State laws and regulations that apply
across San Juan and Lopez Islands
include provisions to limit collection of
butterflies for scientific purposes, but no
specific protections to island marble
butterfly habitats. The island marble
butterfly is currently classified as a
candidate species by the State of
Washington (WDFW 2015a, p. 2).
Candidates are those species considered
by Washington State to be sensitive and
potentially in need of protection
through the process of designation as
endangered, following procedures
established by the Washington
Administrative Code (WAC) (220–610–
110). However, candidates are not
afforded any specific regulatory
protections (Potter 2015c, in litt.). The
island marble butterfly is afforded
limited State regulatory protections
from overcollection as the State of
Washington requires a scientific
collection permit for handling or
collecting any fish, or wildlife, their
nests, or eggs for scientific purposes
(WAC 220–200–150; Revised Code of
Washington (RCW) 77.32.240).
The island marble butterfly was
identified as critically imperiled in the
Washington State Comprehensive
Wildlife Conservation Strategy (WDFW
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2005, pp. 219, 314, 336–337). Since
2005, WDFW has retired the
Comprehensive Wildlife Conservation
Strategy and incorporated it into
Washington’s State Wildlife Action Plan
(SWAP). Although the SWAP addresses
the island marble butterfly’s
conservation status, identifies it as a
‘‘species of greatest conservation need,’’
and recommends conservation actions
(WDFW 2015b, p. 3–39), the SWAP is
not a regulatory mechanism.
WDNR owns the Cattle Point Natural
Resources Conservation Area consisting
of 112 acres directly to the east of
American Camp, a portion of which
provides potentially suitable habitat for
island marble butterflies. Natural
resource conservation areas are
managed to protect outstanding
examples of native ecosystems; habitat
for endangered, threatened, and
sensitive plants and animals; and scenic
landscapes. Removal of any plants or
soil is prohibited unless written
permission is obtained from WDNR
(WAC 332–52–115).
Local Laws and Regulations
American Camp is the only area
known to be occupied by the island
marble butterfly, and because the area is
managed by NPS under the National
Park Service’s Organic Act and
implementing regulations, local laws
and regulations governing land use do
not apply. However, the following local
laws and regulations may provide some
benefit to the island marble butterfly,
should the species expand its range or
recolonize suitable habitat areas outside
American Camp.
The Washington State Growth
Management Act of 1990 (GMA)
requires all jurisdictions in the State to
designate and protect critical areas
(RCW 36.70A). The State defines five
broad categories of critical areas,
including: (1) Wetlands; (2) areas with
a critical recharging effect on aquifers
used for potable water; (3) fish and
wildlife habitat conservation areas; (4)
frequently flooded areas; and (5)
geologically hazardous areas (RCW
36.70A.030). The upland prairie habitat
type that island marble butterflies may
use, but are not restricted to, is
considered both a fish and wildlife
habitat conservation area and an area
with a critical recharging effect on
aquifers under the GMA. Identification
as a fish and wildlife habitat
conservation area mandates that each
county within Washington State
preserve and protect the fish and
wildlife associated with each habitat
conservation area by developing
policies and regulations to protect the
functions and values of critical areas.
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Within counties, the mandate to protect
and regulate critical areas applies to all
unincorporated areas. In addition,
incorporated cities within counties are
required to address critical areas within
their ‘‘urban growth area’’ (UGA; the
area in which urban growth is
encouraged by the municipal
government) independently. The only
incorporated city within San Juan
County is Friday Harbor, which is
located outside of NPS-owned land on
San Juan Island and outside of habitat
currently occupied by the island marble
butterfly. The Friday Harbor
Comprehensive Plan provides no
specific protections for animal species
that are not listed as endangered or
threatened under State or Federal law;
however, Upland Category III may
confer some benefits to the species
based on conservation status of the
species.
San Juan County encompasses the
range of the island marble butterfly. The
County regulates critical areas through a
Critical Areas Ordinance, which
mandates protection for species listed
under the Act through San Juan County
Critical Areas Ordinance (section
18.30.110, Fish and Wildlife Habitat
Conservation Areas). The Critical Areas
Ordinance also identifies species of
local importance, including the island
marble butterfly (San Juan County 2018,
p. 34), and provides protection for the
island marble butterfly by requiring that
development applications for areas
determined to be occupied by the island
marble butterfly develop a habitat
management plan consistent with
County recommendations for the
conservation of the island marble
butterfly prior to permitting. The San
Juan County Comprehensive Plan
recommends that property owners with
occupied island marble butterfly habitat
avoid the use of insecticides and
herbicides, limit grazing and
agricultural disturbance, and protect
areas with larval host plants during the
development process (San Juan County
2018, pp. 51, 56). However, the
conservation recommendations are not
comprehensive enough to prevent local
extirpation of the island marble
butterfly because they do not address all
of the stressors influencing its
persistence (e.g., landscaping,
permanent landscape conversion,
mowing, etc.), as evidenced by the
complete loss of occupied island marble
butterfly habitat within areas developed
since 2006 (see ‘‘Development,’’ above,
under Factor A).
In addition, the San Juan County
Comprehensive Plan concentrates urban
density within UGAs in order to
preserve the rural nature of the San Juan
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archipelago (San Juan County 2010,
entire). We considered the plan in our
2006 12-month finding (71 FR 66292;
November 14, 2006), concluding that
the restriction of high-density
development would lead to the
maintenance of suitable habitat on
Lopez and San Juan Islands. While
preserving the low-density agricultural
environment on San Juan and Lopez
Islands partially prevents the direct
conversion of suitable island marble
butterfly habitat to other incompatible
uses (e.g., impermeable surfaces,
manicured lawns, residential housing),
new evidence indicates that despite
these planning efforts, island marble
butterfly habitat has been severely
curtailed rangewide since 2006, due to
a variety of factors (e.g., mowing,
landscaping, or removal of host plants)
(Miskelly and Potter 2005, p. 6; Miskelly
and Fleckenstein 2007, p. 6; Potter
2015a, in litt.).
Summary of Existing Regulatory
Mechanisms
The island marble butterfly and its
host plant are afforded substantial
regulatory protections from
anthropogenic threats at American
Camp through NPS regulations and the
current general management plan for
San Juan Island National Historical
Park. In addition, State- and Countylevel regulatory mechanisms that
influence development and zoning on
San Juan and Lopez Islands are
generally beneficial to suitable habitat
that could be occupied by the island
marble butterfly in the future. However,
this impressive suite of regulatory
mechanisms has not prevented the
extirpation of other populations, and the
species remains in precarious shape
with only one remaining known
location. Therefore, we conclude that
the existing Federal, State, and local
regulatory mechanisms provide some
benefits to the island marble butterfly
and its habitat, but do not sufficiently
ameliorate the threats to the species
such that it does not meet the definition
of an endangered species.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Under Factor E, we evaluate the
island marble butterfly’s small
population size and its vulnerability to
stochastic events, vehicular collisions,
insecticide application, late emergence
of adult butterflies, and climate change.
Small Population Size and Vulnerability
to Stochastic Events
Since its rediscovery in 1998, the
island marble butterfly has been
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documented to have a narrow
distribution, which has become
increasingly constrained as secure
habitat has been reduced or destroyed
throughout the butterfly’s range
(Miskelly and Potter 2005, entire;
Miskelly and Fleckenstein 2007, entire;
Miskelly and Potter 2009, entire;
Hanson et al. 2009, entire; Hanson et al.
2010, entire; Potter et al. 2011, entire;
Vernon and Weaver 2012, entire;
Weaver and Vernon 2014, entire; Potter
2015a, in litt.; Vernon 2015a, entire).
Declining numbers for the island marble
butterfly have been documented during
annual monitoring at American Camp
that has taken place from 2004 through
2015 (see ‘‘Abundance,’’ above), and the
species now appears to be restricted to
a single known population centered on
American Camp.
Compared to large populations, small
populations are disproportionately
affected by environmental,
demographic, and genetic stochasticity,
and thus face greater risk of extinction
(Frankham 1996, p. 1506; Saccheri et al.
1998, entire; Harper et al. 2003, pp.
3349, 3354). Environmental
stochasticity is the variation in birth and
death rates from one season to the next
in response to weather, disease,
competition, predation, or other factors
external to the population (Shaffer 1981,
p. 131). For example, drought or
predation in combination with a low
population year could result in
extirpation, and butterflies are known to
be sensitive to environmental variation,
increasing the influence of this factor
(Weiss et al. 1993, pp. 267–269).
Stochastic environmental events can be
natural or human-caused.
Demographic stochasticity refers to
random variability in survival or
reproduction among individuals within
a population (Shaffer 1981, p. 131). This
random variability has a proportionately
large effect on small populations, such
that any loss of beneficial alleles (genes
that provide for more successful
reproduction and survival) may result in
a rapid reduction in fitness, making
small populations much more likely to
go extinct than large populations
(Frankham 1996, p. 1507). Genetic
stochasticity, or genetic drift, describes
random changes in the genetic
composition of a population that are not
related to systemic forces such as
natural selection, inbreeding, or
migration. In small populations, genetic
stochasticity is more likely to result in
reduced fitness and ultimately a lower
number of individuals contributed to
each successive generation. Small,
narrowly distributed populations
generally have lower genetic diversity
than larger populations, which can
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result in less resilience to changing
environmental conditions.
Because the island marble butterfly
persists in low numbers, loss of a
portion of the remaining population
could have disproportionately negative
effects. Storm surges that destroy
nearshore habitat containing
overwintering island marble butterfly
chrysalids may further deplete the
genetic diversity of the island marble
butterfly. Similarly, in grassland habitat,
a poorly timed or uncontrolled fire
could destroy a large portion of the
remaining population. The effect of
predation, which has always been at
least a baseline limiting factor for the
island marble butterfly, is magnified
when there are so few individuals left.
Additional stochastic events that could
potentially be devastating include a latespring weather abnormality, such as an
extended hard freeze or a powerful
storm during the flight season; a year in
which predator populations were
unusually high; or introduction of a
novel predator. Given that the very
small population at American Camp is
likely the only remaining population of
the species, we conclude that small
population size makes it particularly
vulnerable to a variety of likely
stochastic events, and this constitutes a
threat to the island marble butterfly at
the individual, population, and species
levels.
Vehicular Collisions
Habitat occupied by the island marble
butterfly within American Camp is
bisected by Cattle Point Road, a
highway that is the only point of access
for a small residential community at the
southeastern tip of San Juan Island
(approximately 100–150 housing units)
and, as such, is routinely driven by the
residents. The highway runs along the
shoulder of Mount Finlayson, a
landscape feature that male island
marble butterflies typically follow when
patrolling for females (Lambert 2016b,
pers. comm.). While there have been no
specific reports of island marble
butterfly road kills, the presence of the
highway within occupied habitat
exposes the species to potential vehicle
collisions. Few studies provide detail on
the scale of vehicle-caused mortality for
invertebrate species, and even fewer
specifically examine butterfly mortality
or the effects of traffic on individual
butterfly species (Seibert and Conover
1991, p. 163; Munguira and Thomas
1992, entire; Rao and Girish 2007,
entire).
One peer-reviewed study that
examined vehicular mortality for
butterflies found that a species in the
same family as the island marble
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butterfly, Pieris rapae, was more likely
to be struck and killed by vehicles in
comparison to the other more sedentary
species in the study, with 7 percent of
a local population killed by cars in a 44day period (Munguira and Thomas
1992, p. 325). The study was conducted
along ‘‘main roads’’ in the United
Kingdom that connected relatively large
cities (Munguira and Thomas 1992, p.
317); thus, it is likely they had more
traffic than the highway at American
Camp. While the authors of the study
did not find the percentage of the
population killed by vehicles to be
significant in comparison to mortality
caused by other natural factors affecting
their survival (Munguira and Thomas
1992, p. 316), the loss of individual
island marble butterflies could have
disproportionately large negative effects
on the species as a whole because of its
restricted range and small population
size.
Male island marble butterflies are
attracted to white (ultraviolet-reflecting)
objects that may resemble females and
have been observed to investigate white
flowers (e.g., field chickweed and
yarrow), white picket fences, and white
lines painted on the surface of roads
(Lambert 2011, p. 47). The highway
through American Camp has fog lines
that are painted white that could be
attractive to adult butterflies, thereby
increasing their risk of being killed by
vehicles. The centerlines on the
highway are painted yellow.
Given the presence of a highway
within the single remaining site
occupied by island marble butterflies,
and their attraction to white road stripes
that are present along the Cattle Point
Road edges, we expect that some
vehicular mortality is likely. However,
we cannot estimate the severity of this
stressor, as vehicular mortality has not
been specifically studied for the island
marble butterfly or documented at
American Camp. Therefore, while there
is the potential for mortality resulting
from vehicular collisions, the best
available information does not indicate
that vehicular collision currently has an
individual-, population-, or specieslevel impact to the island marble
butterfly.
Insecticide Application
The best available information does
not indicate any insecticide use in
proximity to areas that are currently
known to be occupied by the island
marble butterfly at American Camp.
However, remnant patches of
potentially suitable habitat for the
species are located within a matrix of
rural agricultural lands and low-density
residential development, where
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insecticides may be used. One such
insecticide that has the potential to
adversely affect the island marble
butterfly if applied during its larval
phase is Bacillus thuringiensis var.
kurstaki (Btk). This insecticide, derived
from a common soil bacterium, is used
in a wide range of settings, including
organic agriculture, for the control of
lepidopteran (butterfly and moth) pest
species (National Pesticide Information
Center 2015, p. 1; Oregon Health
Authority 2015, p. 1). In forestry, it is
used broadly for the control of the Asian
and European gypsy moth species
(Lymantria dispar, and L. dispar dispar,
respectively) (see WSDA 2015, entire).
Btk is also more generally applied for
other lepidopteran pest species, such as
tent caterpillars (Malacosoma spp.).
Btk has the potential to kill the island
marble butterfly larvae if applied in
close proximity and upwind of an
occupied site. Spraying of Btk has had
adverse effects to nontarget butterfly
and moth species (Severns 2002, p. 169;
Wagner and Miller 1995, p. 19), with
butterfly diversity, richness, and
abundance (density) reduced for up to 2
years following the application of Btk
(Severns 2002, p. 168). One study
demonstrated that most nontarget
lepidopteran species may be more
susceptible to Btk than target species
such as Asian and European gypsy
moths or western tent caterpillars (Haas
and Scriber 1998). For nontarget
lepidopterans, the early instar stages of
larvae are the most susceptible stage
(Wagner and Miller 1995, p. 21).
Large-scale application of Btk in
Washington State is done in a targeted
fashion in response to positive trapping
of pest species. In most years, Btk
application is conducted at the scale of
hundreds of acres per year, although in
years when detection of pest species are
high, such as in 2015, application of Btk
may be scaled up to thousands of acres
in response (WSDA 2015, p. 1). Largescale application of Btk does not
normally overlap with areas where the
island marble butterfly is known to
occur within American Camp, although
if pest species were detected in close
proximity and if the target species is
active at the same time as larvae of the
island marble butterfly, the effect of Btk
treatment could be detrimental. Because
the island marble butterfly produces a
single brood per year, has a spring flight
season, and has developing larvae
during the summer insecticide
application period, this species is more
likely to be susceptible to the adverse
effects of Btk than butterfly species with
later flight and developmental periods
or those that produce multiple broods
per year. Btk is commonly used to
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control tent caterpillars and is likely to
have been used on San Juan Island
(Potter 2015d, in litt.), although the
effect on the island marble butterfly at
American Camp is not documented. At
this time, the best available information
does not indicate that Btk has been
applied at or adjacent to any location
where island marble butterflies are
known to occur.
We recognize that the use of
insecticides could have a negative
impact on larvae of the island marble
butterfly if applied in such a way that
individuals were exposed. However,
there is no documented exposure to
insecticide use in the island marble
butterfly at this time. While there is the
potential for high levels of mortality
resulting from insecticide exposure, we
conclude that insecticide use is not
having a known impact on the island
marble butterfly, principally because of
the low likelihood of exposure at
American Camp.
Late Emergence of Adult Butterflies
Since regular transect surveys for the
island marble butterfly began in 2004,
the first date of the flight period has
shifted an average of approximately 9
days later in the year (USFWS 2016,
unpublished data). The reason for this
change is unclear, and the existing timeseries is too brief to ascertain whether
this change is a trend or part of natural
variability on a longer time scale. For
example, no clear correlation exists
between average winter temperatures
and the beginning of the island marble
flight season and the shift toward later
emergence between 2004 and 2016.
Later emergence cannot currently be
attributed to climate change, although
temperature may play a role. When
conditions inside the captive-rearing lab
for island marble butterflies were cooler
than the ambient temperature in 2015,
butterflies emerged later than the wild
population (Shrum 2015b, in litt.). The
temperature was increased inside in
2016, and the captive and wild adults
emerged at the same time (Weaver
2015b, in litt.; Shrum 2016, in litt.).
Other environmental conditions,
including moisture, likely influence
emergence time as well (Tauber et al.
1998, entire).
Ongoing research has recently
detected a steep increase in mortality for
late-season eggs and larvae compared to
the mortality of early-season eggs, with
none of the larvae observed in study
plots surviving to the fifth instar in 2015
(Lambert 2015d, p. 14). Only a portion
of the mortality documented was
attributable to starvation (25 percent);
the greatest cause of mortality was
attributable to direct predation (60
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percent) (Lambert 2015d, p. 14; see
discussion above under Factor C). The
single, small population of island
marble butterflies likely cannot sustain
the increased late-season predation
pressure, and probable survival of fewer
offspring, over multiple years.
Climate Change
Our analyses under the Act include
consideration of ongoing and projected
changes in climate. The majority of
climate models for the Pacific
Northwest region predict wetter winters,
with an increase in the proportion of
precipitation falling as rain rather than
snow due to increasing ambient
temperature, and drier summers as a
result of reduced snowpack and ensuing
hydrologic drought (Mote and Salathe´
2010, p. 48). No downscaled climate
models specific to the San Juan Island
archipelago are available, and San Juan
Island is not reliant on snowpack for its
water. The portion of San Juan Island
where the known population of the
island marble butterfly occurs is in the
rain shadow of mountain ranges on
Vancouver Island, Canada, and in
Washington State, resulting in weather
patterns commonly drier than much of
the rest of the Pacific Northwest (Mass
2009, entire). While the San Juan Island
archipelago may be subject to the
increasing average annual temperatures
associated with climate change, it is
unclear how changing temperatures will
affect the island marble butterfly.
One predicted stressor associated
with climate change for herbivorous
(plant-eating) insect species is the
potential for the development of
phenological asynchrony (a mismatch in
timing) between insects and their larval
host plants (Bale et al. 2002, p. 8). If an
herbivorous insect emerges earlier or
later than the optimal stage of its larval
host plant, the insect may not be able to
find plants at the right stage for egg
laying, or the insect’s larvae may not
have adequate food resources. If the
insect emerges earlier than its larval
host plant, the plants may not be
detectable, leaving the animal with no
place to lay her eggs, or the plants may
be too small to provide enough forage
for larvae, leading to starvation.
Conversely, if the insect emerges when
the plant is at a later phenological stage,
eggs may be laid on a larval host plant
that has matured to the point that plant
tissues are too tough for the larvae to
consume, or the plant may die before
the insect has acquired enough
resources to survive to the pupation
stage. The island marble butterfly is an
early-flying species, generally emerging
in April and immediately mating and
laying eggs on the larval host plants that
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are available. This strategy ensures that
the host plants are young enough to
provide tender plant tissue for first
instar larvae, which have mouthparts
incapable of consuming anything but
the high-moisture flower buds. In the
absence of access to tender buds, early
instar larvae die from desiccation
(Lambert 2011, p. 12). Although
evidence exists that some larvae of lateemerging island marble butterflies have
suffered starvation (Lambert 2015d, p.
14), perhaps as a result of mismatch
between butterfly and food-plant
phenology, no recurring pattern in such
mismatch exists now that can be
associated with climate change.
However, monitoring of phenology and
survival in the island marble butterfly is
ongoing and may shed light on this
relationship in the future.
Sea-level rise associated with climate
change is expected to continue as polar
ice melts, leading to an increase in
ocean volume (Adelsman et al. 2012, p.
82). The warming climate is also
expected to lead to rising ocean
temperatures resulting in thermal
expansion of the water, which will also
increase the volume of the ocean
(Dalton et al. 2013, p. 70). Both of these
effects of climate change are expected to
lead to rising sea level, which will have
the direct effect of increasing the
impacts of storm surges and flooding
events in low-lying areas, such as the
nearshore lagoon habitat of the island
marble butterfly (MacLennan et al.
2013, pp. 4–5; Vose et al. 2014, p. 381;
Friends of the San Juans 2014, p. 7;
Whitman and MacLennan 2015, in litt.;
NOAA 2015a, entire; NOAA 2015b,
entire). Because the nearshore habitat is
barely above sea level, rise in sea level
increases the risk of inundation and
direct mortality for island marble
butterflies overwintering as chrysalids
in low-lying nearshore habitat. Powerful
storm surges have historically deposited
large amounts of coarse sediment and
driftwood in areas occupied by Menzies’
pepperweed (an estimated 5 to 8 percent
of habitat occupied in 2006) and where
a number of island marble butterflies
were overwintering as chrysalids,
leading to low numbers of individuals
detected in nearshore habitat in years
following a storm surge event (Lambert
2011, pp. 99, 145–146; Lambert 2015f,
in litt.). Due to the small number of
individuals remaining, mortality and
habitat loss resulting from storm surges
likely has a population-level impact on
the island marble butterfly, and we
expect these impacts to increase over
time as an effect of global climate
change.
While some effects of global climate
change, such as sea-level rise and storm
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intensity, are expected to be nearly
universal, warming associated with
climate change is expected to be
variable or even patchy, depending on
localized weather patterns (e.g., patterns
influenced by oceanographic
phenomena such as El Nin˜o and La
Nin˜a) (Adelsman et al. 2012, p. 37). The
Pacific Northwest region of the United
States abuts the eastern edge of the
Pacific Ocean, which warms and cools
in sync with the Pacific Decadal
Oscillation (Mantua and Hare 2002,
entire). Given the unclear direction of
climate trends in the San Juan
archipelago, we cannot conclude that
the island marble butterfly is exhibiting
phenological changes such as later
emergence as a result of climate change,
or that the species will do so in the
future.
Climate conditions that affect
phenology in a given year can have
important impacts to the species,
however. Cooler temperatures are
associated with later emergence of
butterflies reared in captivity (Weaver
2015b, in litt.), and late emergence leads
to a spike in late-season predation on
island butterfly larvae, when spider and
wasp populations are greatest (see
discussions above under Factor C, and
above under ‘‘Late Emergence of Adult
Butterflies’’). Compared with an
abundant species with numerous, welldistributed populations, the island
marble butterfly’s small remaining
population is far more vulnerable to
such fluctuations in mortality.
Conservation Efforts To Reduce Other
Natural or Manmade Factors Affecting
Its Continued Existence
The Service, NPS, and other partners
have been implementing multiple
conservation efforts in an attempt to
ameliorate the threats posed by small
population size, vulnerability to
stochastic events, and insecticide
applications. No conservation efforts
currently address collisions with
vehicles or the effects of climate change.
Below we summarize the conservation
measures that have been implemented
by NPS, WDFW, University of
Washington researchers, and
conservation partners on San Juan
Island to address the threats to the
island marble butterfly described above
under Factor E.
The Service, NPS, and other partners
have conducted conservation efforts to
address the effects of small population
size and vulnerability to stochastic
events on the island marble butterfly
since 2008. Specifically, NPS and other
partners began exploring methods for
captive-rearing island marble butterflies
in 2008. In 2009, 16 island marble
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butterfly individuals were rescued from
a construction site, reared to emergence
as adult butterflies, and released in the
spring of 2010 (Vernon 2015d, p. 2). In
2010, more individuals were reared as
part of a food preference experiment
(Trapp and Weaver 2010, entire), and 32
adults were released in 2011 (Vernon
2015d, p. 5). These opportunistic events
demonstrated that rescue, rearing, and
releasing of island marble butterflies
could be successful. A handbook based
on these captive-rearing events and
more recent efforts was developed to
guide captive-rearing and release efforts
for the island marble butterfly (Vernon
2015d, entire).
In 2013, continued decline in the
number of island marble butterflies
observed in the wild led to the rescue,
captive-rearing, and release of the
species in an effort to improve
survivorship and reverse the trend of
declining numbers, and provide a safety
net against stochastic events. Fortyseven individuals successfully formed
chrysalids, and 40 adult island marble
butterflies emerged in the spring of
2014, and were released at American
Camp (85 percent survival) (Vernon
2015d, p. 3). NPS has scaled up and
streamlined the captive-rearing
program. In 2014, NPS converted an
outbuilding into a rearing facility, and
89 eggs and larvae were brought in for
captive-rearing. Of those, 75 adult
island marble butterflies emerged (84
percent survival) in the spring of 2015,
and were released at American Camp
(Silahua 2015, in litt.). In 2015, 126 eggs
and larvae were brought in for captiverearing, 114 of which survived to
become chrysalids (Silahua 2015, in
litt.). The productivity of the captive
rearing facility has continued to
increase in subsequent years; in 2016,
111 adult island marble butterflies were
released; in 2017, 136; and in 2018, 158
adults were released (SJINHP 2018, in
litt.). In total, more than 500 adult island
marble butterflies have been released
back into the wild through this program
(SJINHP 2018, in litt.).
Although the number of adult island
marble butterflies recorded during
annual surveys remains small (fewer
than 30 butterflies were observed each
year during monitoring for the 2014 and
2015 flight seasons), the captive-rearing
effort has likely provided crucial
support to the population remaining in
the wild and will remain necessary in
the future. We note, that there is no data
available allowing a precise
characterization of the success released
individuals have in contributing to the
overall population of the species.
However, this ongoing conservation
effort to address small population size
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and vulnerability to stochastic events is
not without risk and does not ameliorate
other threats to the species in the long
term. For example, in 2015, individuals
reared in captivity emerged late in the
flight season (on or around May 13)
(Weaver 2015b, in litt.), and available
data suggest that the majority of the
offspring of these captive-reared
individuals died as a result of high lateseason predation rates (Lambert 2015d,
p. 14; see discussion under Factor C,
above). In 2016, the date of emergence
in the captive-rearing facility was better
calibrated to ambient environmental
temperatures by adjusting the
temperature in the facility to match
those of the surrounding outdoor area,
but there are likely to be other
unforeseen challenges to successful
captive-rearing.
Conservation efforts to reduce natural
or manmade factors include efforts to
reduce the application of the insecticide
Btk in close proximity to sites occupied
by the island marble butterfly. The final
decision over the use of insecticide for
control of invasive moths and butterflies
has been, and will continue to be, made
by the Washington State Department of
Agriculture after coordination with the
Service and WDFW. All pesticide used
by the State of Washington is applied in
compliance with label instructions,
which are designed to reduce overspray,
drift, and other negative impacts to
nontarget organisms and areas.
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Summary of Other Natural or Manmade
Factors Affecting Its Continued
Existence
The small population size of the
island marble butterfly makes the
species highly vulnerable to stochastic
events (such as storm surges and climate
anomalies) that directly or indirectly
affect survival and reproductive success
or the extent of habitat. Storm surges,
which can cause direct mortality of
island marble butterflies and habitat
loss, are likely to increase with climate
change. Although successful captiverearing and release of island marble
butterflies is an important achievement
that has supplemented numbers at
American Camp since 2013, threats to
the species and its habitat continue. The
range of the island marble butterfly has
continued to contract at American
Camp, and the number of island marble
butterflies observed annually has
continued to decline. These
conservation efforts will need to be
continued into the future and be
monitored to assess their long-term
conservation value to the island marble
butterfly before we can determine their
efficacy.
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Cumulative Effects
In our analysis of the five factors, we
found that the island marble butterfly is
likely to be affected by loss and
degradation of habitat, direct and
incidental predation, and vulnerabilities
associated with small population size.
Multiple stressors acting in combination
have greater potential to affect the
island marble butterfly than each factor
alone. For example, increased sea level
resulting from climate change may
enhance the impacts of storm surges and
flooding on low-lying coastal habitat
where the one native larval host plant
for the species occurs. The combined
effects of environmental and
demographic stochasticity, especially on
a small population, can lead to a decline
that is unrecoverable and results in
extinction (Brook et al. 2008, pp. 457–
458). The impacts of the stressors
described above, which might be
sustained by a larger, more resilient
population, have the potential in
combination to rapidly affect the size,
growth rate, and genetic integrity of a
species that persists as a small, isolated
population. Thus, factors that, by
themselves, may not have a significant
effect on the island marble butterfly,
may affect the species when considered
in combination.
Determination of Island Marble
Butterfly
Section 4 of the Act (16 U.S.C. 1533)
and its implementing regulations (50
CFR part 424) set forth the procedures
for determining whether a species meets
the definition of ‘‘endangered species’’
or ‘‘threatened species.’’ The Act defines
an ‘‘endangered species’’ as a species
that is ‘‘in danger of extinction
throughout all or a significant portion of
its range,’’ and a ‘‘threatened species’’ as
a species that is ‘‘likely to become an
endangered species within the
foreseeable future throughout all or a
significant portion of its range.’’ The Act
requires that we determine whether a
species meets the definition of
‘‘endangered species’’ or ‘‘threatened
species’’ because of any of the following
factors: (A) The present or threatened
destruction, modification, or
curtailment of its habitat or range; (B)
Overutilization for commercial,
recreational, scientific, or educational
purposes; (C) Disease or predation; (D)
The inadequacy of existing regulatory
mechanisms; or (E) Other natural or
manmade factors affecting its continued
existence.
Status Throughout All of Its Range
As required by the Act, we have
carefully assessed the best scientific and
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commercial information available
regarding the past, present, and future
threats to the island marble butterfly.
Since the species was discovered in the
San Juan Islands in 1998, the species’
range has contracted from five
populations on two islands (San Juan
and Lopez) to a single population, at
American Camp on San Juan Island,
today. The causes of these extirpations
are not well understood, but likely
include habitat loss outside American
Camp from a combination of sources.
Within the single remaining population
at American Camp, the number of sites
where island marble butterflies are
detected during surveys declined from
25 in 2007, to 4 in 2015. Encounter rates
for adult butterflies calculated from
survey data have declined each year,
from almost 2 per 100 meters in 2004,
to about 0.3 per 100 meters in 2015. The
slight increase in this rate in 2016, to 0.6
per 100 meters, does not reverse the
overall trend of decline. Captive rearing
and release of the island marble
butterfly shows promise for bolstering
the remaining population of the species.
However, the potential for this species
to recolonize areas within its historical
range is uncertain due to ongoing,
pervasive habitat degradation that
results from herbivory by deer and other
animals on larval host plants, from plant
succession and invasion by nonnative
plants that render habitat unsuitable for
larval host plants, and potentially from
cultivation and other land uses. The
widespread occurrence of native
(spiders) and nonnative (wasps)
predators of eggs and larvae is also an
ongoing threat that may hamper or
prevent potential recolonizations.
Furthermore, the source for any
recolonizations consists of a single,
small population already vulnerable to
these threats and to stochastic sources of
mortality, such as severe storms and
other climate anomalies.
In summary, we have identified the
following threats to the island marble
butterfly: (1) Habitat loss and
degradation from plant succession and
competition with invasive species that
displace larval host plants; herbivory by
deer, European rabbits, and brown
garden snails; and storm surges (Factor
A); (2) direct predation by spiders and
wasps, and incidental predation by deer
(Factor C); (3) small population size and
vulnerability to stochastic events (Factor
E); and (4) the cumulative effects of
small population size and the restricted
range combined with any stressor that
removes individuals from the
population or decreases the species’
reproductive success (Factor E). These
threats affect the island marble butterfly
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throughout the entirety of its range and
are ongoing and likely to persist into the
foreseeable future. These factors pose
threats to the island marble butterfly
whether considered individually or
cumulatively. The existing regulatory
mechanisms (Factor D) and ongoing
conservation efforts are not currently
sufficient to ameliorate the impact of
these threats; despite intense focused
efforts to conserve the species,
population numbers continue to
decline.
The ongoing threats of habitat loss
and degradation, predation, the effects
of small population size, and stochastic
events that cause mortality or reduce
reproductive success render this species
in its entirety presently in danger of
extinction throughout all of its range.
The Act defines an endangered
species as any species that is ‘‘in danger
of extinction throughout all or a
significant portion of its range’’ and a
threatened species as any species ‘‘that
is likely to become an endangered
species within the foreseeable future
throughout all or a significant portion of
its range.’’ The ongoing threats of
habitat loss and degradation, predation,
the effects of small population size, and
stochastic events that cause mortality or
reduce reproductive success render this
species in its entirety presently in
danger of extinction. Therefore, on the
basis of the best available scientific and
commercial information, we are listing
the island marble butterfly as
endangered in accordance with sections
3(6) and 4(a)(1) of the Act. We find that
threatened species status is not
appropriate for the island marble
butterfly because of its already
contracted range and single remaining
population, because the threats are
ongoing and affecting the entirety of the
species, and because these threats are
expected to continue into the future.
Status Throughout a Significant Portion
of Its Range
Under the Act and our implementing
regulations, a species may warrant
listing if it is in danger of extinction or
likely to become so in the foreseeable
future throughout all or a significant
portion of its range. We have
determined that the island marble
butterfly is in danger of extinction
throughout all of its range, and
accordingly, did not undertake an
analysis of any significant portion of its
range. Because we have determined that
the island marble butterfly warrants
listing as endangered throughout all of
its range, our determination is
consistent with the decision in Center
for Biological Diversity v. Everson, 2020
WL 437289 (D.D.C. Jan. 28, 2020), in
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which the court vacated the aspect of
the 2014 Significant Portion of its Range
Policy that provided the Services do not
undertake an analysis of significant
portions of a species’ range if the
species warrants listing as threatened
throughout all of its range.
Determination of Status
Our review of the best available
scientific and commercial information
indicates that the island marble
butterfly meets the definition of an
endangered species. Therefore, we are
listing the island marble butterfly as an
endangered species in accordance with
sections 3(6) and 4(a)(1) of the Act.
Available Conservation Measures
Conservation measures provided to
species listed as endangered or
threatened species under the Act
include recognition, recovery actions,
requirements for Federal protection, and
prohibitions against certain practices.
Recognition through listing results in
public awareness, and conservation by
Federal, State, Tribal, and local
agencies, private organizations, and
individuals. The Act encourages
cooperation with the States and requires
that recovery actions be carried out for
all listed species. The protection
required by Federal agencies and the
prohibitions against certain activities
are discussed, in part, below.
The primary purpose of the Act is the
conservation of endangered and
threatened species and the ecosystems
upon which they depend. The ultimate
goal of such conservation efforts is the
recovery of these listed species, so that
they no longer need the protective
measures of the Act. Subsection 4(f) of
the Act requires the Service to develop
and implement recovery plans for the
conservation of endangered and
threatened species. The recovery
planning process involves the
identification of actions that are
necessary to halt or reverse the species’
decline by addressing the threats to its
survival and recovery. The goal of this
process is to restore listed species to a
point where they are secure, selfsustaining, and functioning components
of their ecosystems.
Recovery planning includes the
development of a recovery outline
shortly after a species is listed and
preparation of a draft and final recovery
plan. The recovery outline guides the
immediate implementation of urgent
recovery actions and describes the
process to be used to develop a recovery
plan. Revisions of the plan may be done
to address continuing or new threats to
the species, as new substantive
information becomes available. The
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recovery plan identifies site-specific
management actions that set a trigger for
review of the five factors that control
whether a species remains endangered
or may be reclassified from endangered
to threatened (‘‘downlisted’’) or
removed from listed status (‘‘delisted’’),
and methods for monitoring recovery
progress. Recovery plans also establish
a framework for agencies to coordinate
their recovery efforts and provide
estimates of the cost of implementing
recovery tasks. Recovery teams
(composed of species experts, Federal
and State agencies, nongovernmental
organizations, and stakeholders) are
often established to develop recovery
plans. When completed, the recovery
outline, draft recovery plan, and the
final recovery plan will be available on
our website (https://www.fws.gov/
endangered) or from our Washington
Fish and Wildlife Office (see FOR
FURTHER INFORMATION CONTACT).
Implementation of recovery actions
generally requires the participation of a
broad range of partners, including other
Federal agencies, States, Tribes,
nongovernmental organizations,
businesses, and private landowners.
Examples of recovery actions include
habitat restoration (e.g., restoration of
native vegetation), research, captive
propagation and reintroduction, and
outreach and education. The recovery of
many listed species cannot be
accomplished solely on Federal lands
because their range may occur primarily
or solely on non-Federal lands. To
achieve recovery of these species
requires cooperative conservation efforts
on private, State, and Tribal lands.
Following publication of this final
rule, funding for recovery actions will
be available from a variety of sources,
including Federal budgets, State
programs, and cost share grants for nonFederal landowners, the academic
community, and nongovernmental
organizations. In addition, pursuant to
section 6 of the Act, the State of
Washington will be eligible for Federal
funds to implement management
actions that promote the protection or
recovery of the island marble butterfly.
Information on our grant programs that
are available to aid species recovery can
be found at: https://www.fws.gov/grants.
Please let us know if you are
interested in participating in recovery
efforts for the island marble butterfly.
Additionally, we invite you to submit
any new information on this species
whenever it becomes available and any
information you may have for recovery
planning purposes (see FOR FURTHER
INFORMATION CONTACT).
Section 7(a) of the Act requires
Federal agencies to evaluate their
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actions with respect to any species that
is listed as an endangered or threatened
species and with respect to its critical
habitat, if any is designated. Regulations
implementing this interagency
cooperation provision of the Act are
codified at 50 CFR part 402. Section
7(a)(2) of the Act requires Federal
agencies to ensure that activities they
authorize, fund, or carry out are not
likely to jeopardize the continued
existence of any endangered or
threatened species or destroy or
adversely modify its critical habitat. If a
Federal action may affect a listed
species or its critical habitat, the
responsible Federal agency must enter
into consultation with the Service.
Federal agency actions within the
species’ habitat that may require
conference or consultation or both as
described in the preceding paragraph
include management and any other
landscape-altering activities on Federal
lands administered by the Bureau of
Land Management, Farm Service
Agency, Federal Highway
Administration, National Park Service,
U.S Army Corps of Engineers, U.S. Fish
and Wildlife Service, U.S. Department
of Agriculture, and the U.S. Coast
Guard.
The Act and its implementing
regulations set forth a series of general
prohibitions and exceptions that apply
to endangered wildlife. The prohibitions
of section 9(a)(1) of the Act, codified at
50 CFR 17.21, make it illegal for any
person subject to the jurisdiction of the
United States to take (which includes
harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect; or
to attempt any of these) endangered
wildlife within the United States or on
the high seas. In addition, it is unlawful
to import; export; deliver, receive, carry,
transport, or ship in interstate or foreign
commerce in the course of commercial
activity; or sell or offer for sale in
interstate or foreign commerce any
listed species. It is also illegal to
possess, sell, deliver, carry, transport, or
ship any such wildlife that has been
taken illegally. Certain exceptions apply
to employees of the Service, the
National Marine Fisheries Service, other
Federal land management agencies, and
State conservation agencies.
We may issue permits to carry out
otherwise prohibited activities
involving endangered wildlife under
certain circumstances. Regulations
governing permits are codified at 50
CFR 17.22. With regard to endangered
wildlife, a permit may be issued for the
following purposes: For scientific
purposes, to enhance the propagation or
survival of the species, and for
incidental take in connection with
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otherwise lawful activities. There are
also certain statutory exemptions from
the prohibitions, which are found in
sections 9 and 10 of the Act.
It is our policy, as published in the
Federal Register on July 1, 1994 (59 FR
34272), to identify to the maximum
extent practicable at the time a species
is listed, those activities that would or
would not constitute a violation of
section 9 of the Act. The intent of this
policy is to increase public awareness of
the effect of a final listing on proposed
and ongoing activities within the range
of a listed species. Due to the cryptic
nature of this species throughout a large
portion of the year, we are unable, at
this time, to identify specific activities
within the known range of the species
that wouldnot result in unauthorized
take under section 9 of the Act.
Based on the best available
information, the following activities
may potentially result in a violation of
section 9 the Act; this list is not
comprehensive:
(1) Unauthorized collecting, handling,
possessing, selling, delivering, carrying,
or transporting of island marble
butterflies, including import or export
across State lines and international
boundaries, except for properly
documented antique specimens at least
100 years old, as defined by section
10(h)(1) of the Act;
(2) Introduction of nonnative species
that compete with or prey upon the
island marble butterfly or its host and
nectar plants—for example, the
introduction of competing, nonnative
plants or animals to the State of
Washington, and in particular the San
Juan Islands;
(3) The unauthorized release of
biological control agents that attack any
life stage of the island marble
butterfly—for example, Btk release in
the range of the species;
(4) Unauthorized modification of the
soil profiles or the vegetation
components on sites known to be
occupied by island marble butterflies; or
(5) Intentional disturbance of
butterflies (or any life stage thereof),
especially mowing or burning of areas
where butterflies are known to occur
during the breeding season.
Questions regarding whether specific
activities would constitute a violation of
section 9 of the Act should be directed
to the Washington Fish and Wildlife
Office (see FOR FURTHER INFORMATION
CONTACT).
Critical Habitat
Background
Critical habitat is defined in section 3
of the Act as:
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(1) The specific areas within the
geographical area occupied by the
species, at the time it is listed in
accordance with the Act, on which are
found those physical or biological
features
(a) Essential to the conservation of the
species, and
(b) Which may require special
management considerations or
protection; and
(2) Specific areas outside the
geographical area occupied by the
species at the time it is listed, upon a
determination that such areas are
essential for the conservation of the
species.
Our regulations at 50 CFR 424.02
define the geographical area occupied
by the species as an area that may
generally be delineated around species’
occurrences, as determined by the
Secretary (i.e., range). Such areas may
include those areas used throughout all
or part of the species’ life cycle, even if
not used on a regular basis (e.g.,
migratory corridors, seasonal habitats,
and habitats used periodically, but not
solely by vagrant individuals).
Conservation, as defined under
section 3 of the Act, means to use and
the use of all methods and procedures
that are necessary to bring an
endangered or threatened species to the
point at which the measures provided
pursuant to the Act are no longer
necessary. Such methods and
procedures include, but are not limited
to, all activities associated with
scientific resources management such as
research, census, law enforcement,
habitat acquisition and maintenance,
propagation, live trapping, and
transplantation, and, in the
extraordinary case where population
pressures within a given ecosystem
cannot be otherwise relieved, may
include regulated taking.
Critical habitat receives protection
under section 7 of the Act through the
requirement that Federal agencies
ensure, in consultation with the Service,
that any action they authorize, fund, or
carry out is not likely to result in the
destruction or adverse modification of
critical habitat. The designation of
critical habitat does not affect land
ownership or establish a refuge,
wilderness, reserve, preserve, or other
conservation area. Such designation
does not allow the government or public
to access private lands. Such
designation does not require
implementation of restoration, recovery,
or enhancement measures by nonFederal landowners. Where a landowner
requests Federal agency funding or
authorization for an action that may
affect a listed species or critical habitat,
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the consultation requirements of section
7(a)(2) of the Act would apply, but even
in the event of a destruction or adverse
modification finding, the obligation of
the Federal action agency and the
landowner is not to restore or recover
the species, but to implement
reasonable and prudent alternatives to
avoid destruction or adverse
modification of critical habitat.
Under the first prong of the Act’s
definition of critical habitat, areas
within the geographical area occupied
by the species at the time it was listed
are included in a critical habitat
designation if they contain physical or
biological features (1) which are
essential to the conservation of the
species and (2) which may require
special management considerations or
protection. For these areas, critical
habitat designations identify, to the
extent known using the best scientific
and commercial data available, those
physical or biological features that are
essential to the conservation of the
species (such as space, food, cover, and
protected habitat). In identifying those
physical or biological features within an
area, we focus on the specific features
that support the life-history needs of the
species, including, but not limited to,
water characteristics, soil type,
geological features, prey, vegetation,
symbiotic species, or other features. A
feature may be a single habitat
characteristic, or a more complex
combination of habitat characteristics.
Features may include habitat
characteristics that support ephemeral
or dynamic habitat conditions. Features
may also be expressed in terms relating
to principles of conservation biology,
such as patch size, distribution
distances, and connectivity.
Under the second prong of the Act’s
definition of critical habitat, we can
designate critical habitat in areas
outside the geographical area occupied
by the species at the time it is listed,
upon a determination that such areas
are essential for the conservation of the
species. For example, an area currently
occupied by the species but that was not
occupied at the time of listing may be
essential to the conservation of the
species and may be included in the
critical habitat designation.
Section 4 of the Act requires that we
designate critical habitat on the basis of
the best scientific data available.
Further, our Policy on Information
Standards Under the Endangered
Species Act (published in the Federal
Register on July 1, 1994 (59 FR 34271)),
the Information Quality Act (section 515
of the Treasury and General
Government Appropriations Act for
Fiscal Year 2001 (Pub. L. 106–554; H.R.
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5658)), and our associated Information
Quality Guidelines provide criteria,
establish procedures, and provide
guidance to ensure that our decisions
are based on the best scientific data
available. They require our biologists, to
the extent consistent with the Act and
with the use of the best scientific data
available, to use primary and original
sources of information as the basis for
recommendations to designate critical
habitat.
When we are determining which areas
should be designated as critical habitat,
our primary source of information is
generally the information from the
species status assessment (SSA)
document and information developed
during the listing process for the
species. Additional information sources
may include any generalized
conservation strategy, criteria, or outline
that may have been developed for the
species; the recovery plan for the
species; articles in peer-reviewed
journals; conservation plans developed
by States and counties; scientific status
surveys and studies; biological
assessments; other unpublished
materials; or experts’ opinions or
personal knowledge.
Habitat is dynamic, and species may
move from one area to another over
time. We recognize that critical habitat
designated at a particular point in time
may not include all of the habitat areas
that we may later determine are
necessary for the recovery of the
species. For these reasons, a critical
habitat designation does not signal that
habitat outside the designated area is
unimportant or may not be needed for
recovery of the species. Areas that are
important to the conservation of the
species, both inside and outside the
critical habitat designation, will
continue to be subject to: (1)
Conservation actions implemented
under section 7(a)(1) of the Act; (2)
regulatory protections afforded by the
requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their
actions are not likely to jeopardize the
continued existence of any endangered
or threatened species; and (3) section 9
of the Act’s prohibitions on taking any
individual of the species, including
taking caused by actions that affect
habitat. Federally funded or permitted
projects affecting listed species outside
their designated critical habitat areas
may still result in jeopardy findings in
some cases. These protections and
conservation tools will continue to
contribute to recovery of this species.
Similarly, critical habitat designations
made on the basis of the best available
information at the time of designation
will not control the direction and
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substance of future recovery plans,
habitat conservation plans (HCPs), or
other species conservation planning
efforts if new information available at
the time of these planning efforts calls
for a different outcome.
On August 27, 2019, we published a
final rule in the Federal Register (84 FR
45020) to revise our regulations
concerning the procedures and criteria
used for listing or removing species
from the Lists of Endangered and
Threatened Wildlife and Plants and
designating critical habitat. That rule
became effective on September 26, 2019,
but as stated in that rule, the revisions
it sets forth apply to classification and
critical habitat rules for which a
proposed rule was published after
September 26, 2019. Since the proposed
rule for the Island marble butterfly
critical habitat was published on April
12, 2018 (83 FR 15900), this final rule
follows the version of § 424.12 that was
in effect prior to September 26, 2019.
Physical or Biological Features
In accordance with section 3(5)(A)(i)
of the Act and regulations at 50 CFR
424.12(b), in determining which areas
within the geographical area occupied
by the species at the time of listing to
designate as critical habitat, we consider
the physical or biological features that
are essential to the conservation of the
species and which may require special
management considerations or
protection. For example, physical
features might include gravel of a
particular size required for spawning,
alkali soil for seed germination,
protective cover for migration, or
susceptibility to flooding or fire that
maintains necessary early-successional
habitat characteristics. Biological
features might include prey species,
forage grasses, specific kinds or ages of
trees for roosting or nesting, symbiotic
fungi, or a particular level of nonnative
species consistent with conservation
needs of the listed species. The features
may also be combinations of habitat
characteristics and may encompass the
relationship between characteristics or
the necessary amount of a characteristic
needed to support the life history of the
species. In considering whether features
are essential to the conservation of the
species, the Service may consider an
appropriate quality, quantity, and
spatial and temporal arrangement of
habitat characteristics in the context of
the life-history needs, condition, and
status of the species. These
characteristics include, but are not
limited to, space for individual and
population growth and for normal
behavior; food, water, air, light,
minerals, or other nutritional or
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physiological requirements; cover or
shelter; sites for breeding, reproduction,
or rearing (or development) of offspring;
and habitats that are protected from
disturbance.
We derive the specific physical or
biological features essential to the
conservation of the island marble
butterfly from studies of this species’
habitat, ecology, and life history as
described below. We have determined
that the following physical or biological
features are essential to the conservation
of the island marble butterfly:
Space for Individual and Population
Growth and for Normal Behavior
The island marble butterfly has
previously been documented as having
as many as five core populations across
San Juan and Lopez Islands in the San
Juan archipelago, but of those five, there
is only one location where it has been
consistently detected on an annual basis
since its rediscovery in 1998 at
American Camp, part of San Juan Island
National Historical Park. The long-term
occupancy of American Camp indicates
that one or more aspects of this site
provide the combination of habitat
factors needed by the species. American
Camp encompasses multiple small
populations within large expanses of
diverse habitat, including open southfacing slopes, varied broad-scale
topographic features, and low-statured
plant communities (Lambert 2011, pp.
151–152; Lambert 2016a, p. 4). Surface
topography (slope and aspect) and
landscape features that have
topographic relief (slopes, bluffs, sand
banks, or driftwood berms) are critical
to the movement and dispersal of the
island marble butterfly (Lambert 2011,
p. 152).
The portion of the park where the
island marble butterfly persists contains
an open expanse of prairie and dune
habitat greater than 700 ac (283 ha) and
is bounded on two sides by marine
shoreline. The island marble butterfly
uses landscape features to fly low across
the land, following shallow ridgelines
associated with sand dunes, road cuts,
and coastal bluffs. We surmise that
island marble butterflies use the lee of
rolling hills or hollows in broader
expanses of prairie and dune habitats to
facilitate their movements. Therefore,
we determine habitat areas large enough
to include broad topographic features
(e.g., ridgelines, hills, and bluffs) to be
physical or biological features for the
island marble butterfly.
At a rangewide scale, the island
marble butterfly exhibits
metapopulation dynamics, while on a
local scale, ‘‘patchy’’ population
dynamics best describes the movement
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of individuals between suitable habitat
patches (Lambert 2011, pp. 147–148).
Specifically, the island marble butterfly
tends to occupy multiple habitat
patches within a larger, heterogeneous
area, with some small amount of
movement between suitable habitat
patches. Individual butterflies rarely
move distances greater than 0.4 mi (600
m) (Peterson 2010, p. 3). Marked
individuals are nearly always
recaptured at the sites where they were
marked, with a single exception when a
marked individual was recaptured 1.2
mi (1.9 km) from its site of origin
(Peterson 2010, p. 3). Within the last
known occupied site, smaller occupied
patches have been observed to undergo
local extirpation events, but the close
proximity of nearby populations within
the larger contiguous area has allowed
for recolonization (Lambert 2011, p.
155). Areas large enough to contain
multiple small populations of island
marble butterfly that allow for
population connectivity and reestablishment are essential to the
conservation of the species. Therefore,
we conclude that areas large enough to
support multiple small populations of
the species are a physical or biological
feature essential to the island marble
butterfly.
Island marble butterflies tend to fly
close to the ground, along the edges of
treed areas or along marine shorelines.
Therefore, forest and open water create
natural barriers to movement (Lambert
2011, pp. 49, 50). Male island marble
butterflies fly low (approximately 5 ft
(1.5 m) above the ground) and follow
ridgelines, bluffs, road-cuts, trail edges,
fence lines, and shrub or forest edges in
search of mates (Lambert 2011, pp. 47–
48). Female island marble butterflies
have been observed to fly in low
(approximately 3 ft (1 m) above the
ground), wide (330–980 ft (100–500 m))
circles above the ground searching for
suitable host plants upon which to lay
their eggs (Lambert 2011, p. 49). We
conclude that large open areas with few
trees are a physical or biological feature
for the island marble butterfly.
Based on the best information
available, we estimate that the
conservation of the island marble
butterfly is best supported by open,
primarily treeless areas with shortstatured forb- and grass-dominated
vegetation. Areas should be large
enough to allow for the inclusion of
diverse topographic features and habitat
types, including sites for mating, egg
laying, feeding, refugia (places to safely
harbor), and diapause locations, and
should support multiple discrete
occupied habitat patches, which
increases the likelihood of
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recolonization if local extinction takes
place. Therefore, we conclude that
open, primarily treeless habitat areas
that are large enough to support
multiple, small populations and that
include broad topographic features such
as ridgelines, hills, and bluffs are
physical or biological features essential
to the conservation of the island marble
butterfly.
Food, Water, Air, Light, Minerals, or
Other Nutritional or Physiological
Requirements
The island marble butterfly needs
larval and adult food resources in order
to complete its life cycle: larval host
plants (food plants required by the
immature stages of the butterfly) and
nectar plants for the adults. The island
marble butterfly has three known larval
host plants, all in the mustard family
(Brassicaceae). One is native, Menzies’
pepperweed, and two are nonnative,
field mustard and tumble mustard
(Miskelly 2004, pp. 33, 38; Lambert
2011, p. 2). These three larval host
plants are essential components of
habitat for the island marble butterfly.
All three larval host plants occur in
open grass- and forb-dominated plant
communities, but each species is most
robust in one of three specific habitat
types, with little overlap: Menzies’
pepperweed at the edge of low-lying
coastal lagoon habitat; field mustard in
upland prairie habitat, disturbed fields,
and disturbed soils, including soil piles
from construction; and tumble mustard
in sand dune habitat (Miskelly 2004, p.
33; Miskelly and Potter 2009, p. 9;
Lambert 2011, pp. 24, 121–123). While
each larval host plant can occur in each
of the three habitat types referenced
above, female island marble butterflies
typically lay eggs on only the most
robust host plants in each
aforementioned habitat type (Miskelly
2004, p. 33; Lambert 2011, pp. 24, 41,
50, 55–57, 121–123).
We conclude that the presence of
Menzies’ pepperweed, field mustard, or
tumble mustard is a physical or
biological feature upon which the island
marble butterfly depends.
Adults primarily forage for nectar on
their larval host plants (Potter 2015e,
pers. comm.). They also use a variety of
other nectar plants that flower during
the island marble butterfly’s flight
period, which is generally from midApril to mid- to late-June. Adults have
been observed to nectar on yellow sand
verbena, yarrow, small-flowered
fiddleneck, American sea rocket, field
chickweed, common stork’s bill,
dovefoot geranium, hairy cat’s ear,
common lomatium, seashore lupine,
common forget-me-not, California
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buttercup, trailing blackberry,
dandelion, death camas, and Howell’s
brodiaea (Miskelly 2004, p. 33; Pyle
2004, pp. 23–26, 33; Miskelly and Potter
2005, p. 6; Lambert 2011, p. 120; Vernon
and Weaver 2012, appendix 12; Lambert
2015a, p. 2; Lambert 2015b, in litt.). Of
these additional nectar resources, island
marble butterflies are most frequently
observed feeding on yellow sand
verbena, small-flowered fiddleneck, and
field chickweed (Potter 2015e, pers.
comm.). We conclude that adult nectar
resources, including, but not limited to,
those listed here, are a physical or
biological feature upon which the island
marble butterfly depends.
Like many animals that rely on
external sources of body heat
(ectotherms), the island marble butterfly
is more active at warmer temperatures;
for this species, this generally means
temperatures that are higher than 55
degrees Fahrenheit (°F) (13 degrees
Celsius (°C)). This leads to adult
(winged) island marble butterflies being
most active between the hours of 10
a.m. and 4 p.m. The island marble
butterfly relies upon solar radiation for
the warmth that drives their
development, mate-finding, and
reproduction. We conclude that
exposure to the sun provided by open,
primarily treeless areas with some
south-facing slopes and short-statured
vegetation is a physical or biological
feature upon which the island marble
butterfly depends.
We consider open sunlit areas
containing at least one species of larval
host plant, Menzies’ pepperweed, field
mustard, and/or tumble mustard, with
both flower buds and blooms between
the months of May through July to be
physical or biological features of island
marble butterfly habitat. We
additionally consider the presence of
adult nectar plants in flower to be a
physical or biological feature of island
marble butterfly habitat.
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Sites for Breeding, Reproduction, or
Rearing (or Development) of Offspring
Male island marble butterflies are
attracted to white and may investigate
white picket fences, white lines on
surface roads, or other white objects
while searching for a mate (Lambert
2011, p. 47). The island marble butterfly
primarily uses short-statured, whiteflowering plants such as field
chickweed as sites for mate attraction
and mating (Lambert 2014b, p. 17). We
conclude that the presence of shortstatured, white-flowering plants during
the flight period (generally from midApril to mid- to late-June) for the island
marble butterfly to be a physical or
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biological feature of the island marble
butterfly habitat.
Once mated, gravid female island
marble butterflies seek out larval host
plants at an optimal growth stage for egg
laying (recently hatched caterpillars
require tender plant parts, such as
immature flower buds, because their
mouthparts are not developed enough to
eat hardened plant matter) (Lambert
2011, pp. 9–10). Larval host plant
flowering phenology (timing of flower
opening) is important for island marble
butterflies. If the plants emerge too
early, there may not be enough tissue at
the right stage available for the larvae to
go through their developmental phases.
If the plants emerge too late, female
butterflies may not recognize the larval
host plants as suitable sites to lay eggs.
Female island marble butterflies
carefully gauge the suitability of each
larval host plant, preferentially selecting
plants that possess both flowers and
buds to lay eggs on. Plants with greater
than 50 percent of their flowers in
bloom are more likely to be selected
than plants in an earlier (less than 50
percent of flowers in bloom) or later
developmental stage (Lambert 2011, pp.
59–60). Female island marble butterflies
tend to lay eggs singly on the immature
buds of the flowers of their larval host
plants, rarely laying eggs on
inflorescences that are already occupied
by island marble butterfly eggs or larvae
(Lambert 2011, pp. 51–57). Female
island marble butterflies prefer larval
host plants growing in low-density
patches with less than one plant per
meter square and tend to choose plants
that are along the outer edge of a patch
of larval host plants rather than in areas
with a high density of host plants
(Lambert 2011, pp. 53, 68–69; Lambert
2015d, p. 9). Additionally, host plant
phenology (timing of development)
plays a significant role in determining
where females lay eggs. Low- to
medium-density larval host plants, with
both flower buds and blooms on them
between the months of May through
July, for egg-laying and larval
development are a physical or biological
feature of island marble butterfly
habitat.
After hatching, larvae of the island
marble butterfly rapidly progress
through five instars (larval growth
stages) and have been documented to
then move up to 13 ft (4 m) from their
larval host plant to nearby standing
vegetation (usually tall grasses) to
pupate (Lambert 2011, p. 19). Island
marble butterfly larvae use nearby
vegetation as bridges to other plants and
appear to avoid being close to the
ground while searching for a safe site on
which to form a chrysalis (pupal casing)
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(Lambert 2011, pp. 20–21). Therefore,
we find that the presence of larval host
plants, in complement with tall,
standing vegetation that provides the
structure necessary to allow mature
larvae to cross to a safe pupation site,
is a physical or biological feature of
island marble butterfly habitat.
Habitats That Are Protected From
Disturbance or Are Representative of the
Historical, Geographical, and Ecological
Distributions of a Species
The island marble butterfly spends
approximately 300 days in diapause (a
form of dormancy) as a chrysalis (pupa)
before undergoing metamorphosis to
emerge as a winged adult the following
spring. Unlike other butterfly species
that may diapause underground or,
alternatively, rapidly advance from egg
to winged adult and overwinter in an
adult phase, the island marble butterfly
enters diapause aboveground and very
close to where it hatched. During
diapause, the island marble butterfly is
vulnerable to any activity such as
trampling, mowing, harvesting, grazing,
or plowing that may disturb or destroy
the vegetative structure to which a larva
has attached its pupal casing. The larval
host plants for the island marble
butterfly are annual (or biennial), and
habitat patches for the island marble
butterfly do not tend to persist in the
same area continuously over time.
Leaving the vegetation near where larval
host plants established in the spring
until mid-summer the following year
provides a safe place for the island
marble butterfly chrysalids to harbor
until they emerge. Therefore, we find
that sufficient areas of undisturbed
vegetation surrounding larval host
plants that are left standing for a
sufficient period of time in order for the
island marble butterfly to complete its
life cycle is a physical or biological
feature of island marble butterfly
habitat.
Summary of Essential Physical or
Biological Features
We have determined that the
following physical or biological features
of the areas on San Juan Island,
Washington, that are essential to the
conservation of the island marble
butterfly are:
(a) Open, primarily treeless areas with
short-statured forb- and grass-dominated
vegetation that include diverse
topographic features such as ridgelines,
hills, and bluffs for patrolling, dispersal
corridors between habitat patches, and
some south-facing terrain. Areas must
be large enough to allow for the
development of patchy-population
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dynamics, allowing for multiple small
populations to establish within the area.
(b) Low- to medium-density larval
host plants, with both flower buds and
blooms on them between the months of
May through July, for egg-laying and
larval development. Larval host plants
may be any of the following: Brassica
rapa, Sisymbrium altissimum, or
Lepidium virginicum.
(c) Adult nectar resources in flower
and short-statured, white-flowering
plants in bloom used for mate-finding,
which may include, but are not limited
to, Abronia latifolia (yellow sand
verbena), Achillea millefolium (yarrow),
Amsinckia menziesii (small-flowered
fiddleneck), Cakile edentula (American
sea rocket), Cerastium arvense (field
chickweed), Erodium cicutarium
(common stork’s bill), Geranium molle
(dovefoot geranium), Hypochaeris
radicata (hairy cat’s ear), Lomatium
utriculatum (common lomatium),
Lupinus littoralis (seashore lupine),
Myosotis discolor (common forget-menot), Ranunculus californicus
(California buttercup), Rubus ursinus
(trailing blackberry), Taraxacum
officinale (dandelion), Toxicoscordion
venenosum (death camas, formerly
known as Zigadenus venenosus), and
Triteleia grandiflora (Howell’s brodiaea,
formerly Brodiaea howellii).
(d) Areas of undisturbed vegetation
surrounding larval host plants sufficient
to provide secure sites for diapause and
pupation. The vegetation surrounding
larval host plants must be left standing
for a sufficient period of time for the
island marble butterfly to complete its
life cycle.
Special Management Considerations or
Protection
When designating critical habitat, we
assess whether the specific areas within
the geographical area occupied by the
species at the time of listing contain
features that are essential to the
conservation of the species and which
may require special management
considerations or protection. Because
the island marble butterfly depends on
vegetation that requires disturbance and
open areas to establish, special
management may be necessary to both
maintain low-level disturbance and to
prevent the invasion of weedy native
and nonnative plant species, such as
Douglas fir, Mediterranean pasture
grasses, and thistle. Beneficial special
management activities could include
prescribed burning to remove standing
vegetation and seedlings and to reduce
seed set of nonnative plant species.
Additionally, the application of
selective herbicides to combat specific
invasive plants may also prove useful in
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vegetation management. For some
weedy species, hand-pulling can be an
effective vegetation management tool, if
staffing and resources allow.
Special management considerations
within the critical habitat unit may
include protection of larval host plants
from herbivory by browsing deer,
European rabbits, and brown garden
snails. These herbivores constitute the
primary threat to the larval host plants
upon which the island marble butterfly
depends. Special management actions
that could ameliorate the threat of
herbivory by deer, European rabbits,
and brown garden snails could include
lethal control methods, such as targeted
hunting or professional removal. For
deer, exclusion fencing increases the
survivorship of both larval host plants
and the island marble butterfly in the
fenced areas, but the fences are difficult
to erect and maintain and provide a host
of other challenges for the land
management agencies. Additionally,
exclusion fencing does nothing to
reduce the number of deer, which is the
primary cause of the intense browsing
pressure on the larval host plants for the
island marble butterfly (Lambert 2011,
pp. 85–104, 127; Lambert 2014a, p. 3;
Lambert 2015d, pp. 14–18). Fencing is
not effective against European rabbits
and brown garden snails.
Criteria Used To Identify Critical
Habitat
As required by section 4(b)(2) of the
Act, we use the best scientific data
available to designate critical habitat. In
accordance with the Act and our
implementing regulations at 50 CFR
424.12(b), we review available
information pertaining to the habitat
requirements of the species and identify
specific areas within the geographical
area occupied by the species at the time
of listing and any specific areas outside
the geographical area occupied by the
species to be considered for designation
as critical habitat. In this case, we are
not designating any areas outside the
geographical area occupied by the
species.
When we are determining which areas
should be designated as critical habitat,
our primary source of information is
generally the information developed
during the listing process for the
species. Additional information sources
may include the recovery plan for the
species, articles in peer-reviewed
journals, conservation plans developed
by States and counties, scientific status
surveys and studies, biological
assessments, other unpublished
materials, or experts’ opinions or
personal knowledge. In this case, we
used existing occurrence data for the
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26811
island marble butterfly and information
on the habitat and ecosystems upon
which it depends. These sources of
information included, but were not
limited to:
(1) Data used to prepare the rule to list
the species;
(2) Information from biological
surveys;
(3) Various agency reports and
databases;
(4) Information from NPS and other
cooperators;
(5) Information from species experts;
(6) Data and information presented in
academic research theses; and
(7) Regional Geographic Information
System (GIS) data (such as species
occurrence data, land use, topography,
aerial imagery, soil data, and land
ownership maps) for area calculations
and mapping.
Areas Occupied at the Time of Listing
In accordance with the Act and our
implementing regulations at 50 CFR
424.12(b), we reviewed available
information pertaining to the habitat
requirements of the species, identified
specific areas within the geographical
area occupied by the species at the time
of listing, and examined whether we
could identify any specific areas outside
the geographical area occupied by the
species to be considered for designation
as critical habitat. In this case, as we are
listing the island marble butterfly
concurrently with the designation of
critical habitat, all areas presently
occupied by the island marble butterfly
constitute those areas occupied at the
time of listing.
We plotted the known locations of the
island marble butterfly where they
occur in Washington using 2015
National Agriculture Imagery Program
(NAIP) digital imagery in ArcGIS,
version 10.4 (Environmental Systems
Research Institute, Inc.), a computer
geographic information system program,
and determined that the currently
occupied areas contain the physical or
biological features needing special
management, as discussed above. We
also analyzed the appropriate quantity
and spatial arrangement of these
features in the context of the life history,
status, and conservation needs of the
species.
We note that limitations in available
GIS data and the scale of designations
can affect our precision in mapping
critical habitat boundaries. We strive to
use clearly recognizable geographic or
legal features in designating critical
habitat boundaries; however, in those
instances where we think critical habitat
maps may cause uncertainty over the
precise extent of mapped critical
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habitat, we have attempted to clarify
with supplemental narrative
descriptions.
Survey effort for the island marble
butterfly has not been consistent
spatially or temporally. Island-wide
surveys of San Juan and Lopez Islands
were discontinued by WDFW in 2012,
due to decreased detections and the lack
of larval host plants in previously
occupied areas across both islands. In
2015, the Service funded an island-wide
survey of San Juan, and no occurrences
were documented outside of the known
occupied area centered on American
Camp at the southern end of San Juan
Island. The last survey of Lopez Island
was conducted in 2012, and a single
larva was observed. There have been no
reports of island marble butterflies from
Lopez Island since 2012.
Therefore, the Service considers areas
to be occupied at the time of listing if
there are occurrence records within
those areas within the last 5 years, or if
areas adjacent to known occupied areas
have the physical or biological features
upon which the island marble butterfly
depends and there are no barriers to
dispersal. It is reasonable to conclude
that the species regularly occurs in such
areas because of the species’ population
dynamics and frequent movement
between habitat patches, as discussed
above. Occurrence records are deemed
credible if recorded by a Federal, State,
or contract biologist, or a qualified
surveyor for the island marble butterfly.
We have also determined that all of
these occupied areas (areas with
documented occurrences as well as
adjacent areas containing suitable
habitat and where there are no barriers
to dispersal) contain one or more of the
essential physical or biological features.
For these reasons and due to the
restricted range of the island marble
butterfly, we determined that all known
occupied areas should be designated as
critical habitat. The only known
occupied area is centered on American
Camp at San Juan Island National
Historical Park and includes adjacent
lands to the east and west of the
National Park that are owned and/or
managed by BLM, WDNR, San Juan
County, Washington State Parks and
Recreation, and private individuals.
The critical habitat designated on the
private parcels along Eagle Cove only
includes the area of steep coastal bluff
between the marine shoreline and the
upland edge at the top of the bluff. It
does not include areas landward of the
top of the bluff, which are typically
mowed and maintained as yard.
When determining critical habitat
boundaries within this final rule, we
made every effort to avoid including
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developed areas such as lands covered
by buildings, pavement, and other
structures because such lands lack
physical or biological features for the
island marble butterfly. The scale of the
maps we prepared under the parameters
for publication within the Code of
Federal Regulations may not reflect the
exclusion of such developed lands. Any
such lands inadvertently left inside
critical habitat boundaries shown on the
maps of this final rule have been
excluded by text in the rule and are not
designated as critical habitat. Therefore,
a Federal action involving these lands
will not trigger section 7 consultation
with respect to critical habitat and the
requirement of no adverse modification
unless the specific action would affect
the physical or biological features in the
adjacent critical habitat. Please note that
we specifically include road margins
and shoulders in the critical habitat
designation, as the island marble
butterfly larval host plants often
establish in these disturbed areas and
may be used by the island marble
butterfly for egg-laying and
development. Special management
considerations for road margins and
shoulders may apply.
We are not designating any areas as
critical habitat outside the geographical
area occupied by the species at the time
of listing. While we know the
conservation of the species will depend
on increasing the number and
distribution of populations of the island
marble butterfly, not all of its historical
range will be essential to the
conservation of the species, and we are
unable to delineate any specific
unoccupied areas that are essential at
this time. Sites both within and outside
of the central valleys of San Juan and
Lopez Islands were previously occupied
by the island marble butterfly. A
number of areas within and outside of
these valleys continue to contain some
or could develop many of the physical
and biological features upon which the
species depends, although the best
available scientific data indicate all
these areas are currently unoccupied.
The areas of the central valleys with the
potential to support the physical and
biological features continue to be
important to the overall conservation
strategy for the island marble butterfly.
However, due to the ephemeral and
patchy nature of island marble butterfly
habitat, only some of these areas within
these larger central valley landscapes
will likely be essential to the species’
long-term persistence and conservation
because of the ease with which field
mustard recruits and the uncertainty
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associated with habitat patch longevity
at any one site.
Any specific areas essential to the
species’ conservation within these
broader landscapes are not currently
identifiable due to our limited
understanding regarding the ideal
configuration for the development of
future habitat patches to support the
island marble butterfly’s persistence, the
ideal size and number of these habitat
patches, and how these habitat patches
may naturally evolve within and persist
on the landscape. Finally, the specific
areas needed for conservation will
depend in part on landowner
willingness to restore and maintain the
species’ habitat in these areas.
Consequently, the Service is
considering proposing the future
establishment of one or more
experimental populations (such as, but
not limited to, those provided for under
section 10(j) of the Act) within these
broad geographic areas after we list the
island marble butterfly under the Act.
Section 10(j) of the Act authorizes the
Service, by rulemaking, to establish new
populations of listed species that are
within the species’ historical range but
outside its current natural range. If we
designate a nonessential population, we
can adopt a rule to minimize restrictions
on landowners. Any such rule would, to
the maximum extent practicable,
represent an agreement between the
Service and affected landowners and
government agencies (50 CFR 17.81(d)).
The critical habitat unit was
designated based on one or more of the
elements of physical or biological
features being present to support island
marble butterfly life processes. The
critical habitat unit contains all of the
identified elements of physical or
biological features and supports
multiple life processes. Some segments
contain only some elements of the
physical or biological features necessary
to support the island marble butterfly’s
particular use of that habitat.
The critical habitat designation is
defined by the map or maps, as
modified by any accompanying
regulatory text, presented at the end of
this document under Regulation
Promulgation. We include more detailed
information on the boundaries of the
critical habitat designation in the
preamble of this document. We will
make the coordinates or plot points or
both on which each map is based
available to the public on https://
www.regulations.gov at Docket No.
FWS–R1–ES–2016–0145, on our
internet site at https://www.fws.gov/
wafwo/, and at the field office
responsible for the designation (see FOR
FURTHER INFORMATION CONTACT, above).
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Final Critical Habitat Designation
We are designating one unit as critical
habitat for the island marble butterfly.
The critical habitat area described below
constitutes our best assessment at this
time of areas that meet the definition of
26813
critical habitat. Table 1 shows the unit,
which is occupied.
TABLE 1—DESIGNATED CRITICAL HABITAT FOR THE ISLAND MARBLE BUTTERFLY
Size of
unit in acres
(hectares)
Critical habitat unit
Land ownership by type
Island marble butterfly critical habitat ..........................................................................
NPS ...........................................................
BLM ...........................................................
DHS ..........................................................
WDNR and SJCLB ...................................
WDNR .......................................................
SJCPD ......................................................
Private .......................................................
718 (291)
19 (8)
5 (2)
1 (0.4)
37 (15)
30 (12)
2 (0.8)
Total: .....................................................................................................................
...................................................................
812 (329)
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Note: Area sizes may not sum due to rounding. NPS = National Park Service, BLM = Bureau of Land Management, DHS = Department of
Homeland Security (Coast Guard), WDNR = Washington Department of Fish and Wildlife, SJCLB = San Juan County Land Bank, SJCPD = San
Juan County Parks Department.
The critical habitat designation
consists of 812 ac (329 ha) of land at the
southern end of San Juan Island, with
San Juan Island National Historical Park
(NPS) being the largest landholder of
718 ac (291 ha). The Bureau of Land
Management (BLM) owns and manages
19 ac (8 ha), Washington Department of
Natural Resources (WDNR) owns and
manages 37 ac (15 ha) at Cattle Point,
the Department of Homeland Security
owns 5 ac (2 ha), WDNR and the San
Juan County Land Bank (SJCLB) jointly
own 1 ac (0.4 ha), San Juan County
Parks Department owns 30 ac (12 ha),
and approximately 2 ac (0.8 ha) is in
private ownership. The critical habitat
designation is centered on the American
Camp portion of San Juan Island
National Historical Park, which is
owned and managed by the National
Park Service, but includes adjacent
lands both to the east and the west of
National Park Service lands. Boundaries
for the critical habitat unit follow the
open, generally treeless habitat that the
island marble butterfly relies upon
during its flight period for mate-finding,
reproduction, feeding, and dispersal.
The entirety of the critical habitat unit
is within the geographical area occupied
at the time of listing. The designation
contains all of the physical or biological
features required to support the island
marble butterfly. The critical habitat
designation is almost entirely conserved
for use by or for the benefit of the public
and is heavily used for recreation,
primarily in the form of day hiking on
easy trails. NPS has maintained a
conservation agreement for the island
marble butterfly with the Service since
2006, with the most recent renewal
signed in December of 2018. As the
largest landholder within the critical
habitat unit, NPS continues to support
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and participate in ongoing research
integral to the conservation of the island
marble butterfly. BLM, DHS, WDNR,
SJCLB, and San Juan County Parks are
all engaged in the conservation of the
island marble butterfly and meet with
the Service multiple times annually to
coordinate conservation efforts.
Within the critical habitat
designation, all of the current threats to
the island marble butterfly are present.
Please see Determination, above, for a
summary of the threats and ‘‘Special
Management Considerations or
Protection’’ for additional
recommendations.
Effects of Critical Habitat Designation
Section 7 Consultation
Section 7(a)(2) of the Act requires
Federal agencies, including the Service,
to ensure that any action they fund,
authorize, or carry out is not likely to
jeopardize the continued existence of
any endangered species or threatened
species or result in the destruction or
adverse modification of designated
critical habitat of such species. In
addition, section 7(a)(4) of the Act
requires Federal agencies to confer with
the Service on any agency action which
is likely to jeopardize the continued
existence of any species proposed to be
listed under the Act or result in the
destruction or adverse modification of
proposed critical habitat.
We published a final rule with a new
definition of destruction or adverse
modification on February 11, 2016 (81
FR 7214). Destruction or adverse
modification means a direct or indirect
alteration that appreciably diminishes
the value of critical habitat for the
conservation of a listed species. Such
alterations may include, but are not
limited to, those that alter the physical
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or biological features essential to the
conservation of a species or that
preclude or significantly delay
development of such features.
If a Federal action may affect a listed
species or its critical habitat, the
responsible Federal agency (action
agency) must enter into consultation
with us. Examples of actions that are
subject to the section 7 consultation
process are actions on State, tribal,
local, or private lands that require a
Federal permit (such as a permit from
the U.S. Army Corps of Engineers under
section 404 of the Clean Water Act (33
U.S.C. 1251 et seq.) or a permit from the
Service under section 10 of the Act) or
that involve some other Federal action
(such as funding from the Federal
Highway Administration, Federal
Aviation Administration, or the Federal
Emergency Management Agency).
Federal actions not affecting listed
species or critical habitat, and actions
on State, tribal, local, or private lands
that are not federally funded or
authorized, do not require section 7
consultation.
As a result of section 7 consultation,
we document compliance with the
requirements of section 7(a)(2) through
our issuance of:
(1) A concurrence letter for Federal
actions that may affect, but are not
likely to adversely affect, listed species
or critical habitat; or
(2) A biological opinion for Federal
actions that may affect and are likely to
adversely affect, listed species or critical
habitat.
When we issue a biological opinion
concluding that a project is likely to
jeopardize the continued existence of a
listed species and/or destroy or
adversely modify critical habitat, we
provide reasonable and prudent
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alternatives to the project, if any are
identifiable, that would avoid the
likelihood of jeopardy and/or
destruction or adverse modification of
critical habitat. We define ‘‘reasonable
and prudent alternatives’’ (at 50 CFR
402.02) as alternative actions identified
during consultation that:
(1) Can be implemented in a manner
consistent with the intended purpose of
the action,
(2) Can be implemented consistent
with the scope of the Federal agency’s
legal authority and jurisdiction,
(3) Are economically and
technologically feasible, and
(4) Would, in the Service Director’s
opinion, avoid the likelihood of
jeopardizing the continued existence of
the listed species and/or avoid the
likelihood of destroying or adversely
modifying critical habitat.
Reasonable and prudent alternatives
can vary from slight project
modifications to extensive redesign or
relocation of the project. Costs
associated with implementing a
reasonable and prudent alternative are
similarly variable.
Regulations at 50 CFR 402.16 require
Federal agencies to reinitiate
consultation on previously reviewed
actions in instances where we have
listed a new species or subsequently
designated critical habitat that may be
affected and the Federal agency has
retained discretionary involvement or
control over the action (or the agency’s
discretionary involvement or control is
authorized by law). Consequently,
Federal agencies sometimes may need to
request reinitiation of consultation with
us on actions for which formal
consultation has been completed, if
those actions with discretionary
involvement or control may affect
subsequently listed species or
designated critical habitat.
Application of the ‘‘Adverse
Modification’’ Standard
The key factor related to the adverse
modification determination is whether,
with implementation of the Federal
action, the affected critical habitat
would continue to serve its intended
conservation role for the species.
Activities that may destroy or adversely
modify critical habitat are those that
result in a direct or indirect alteration
that appreciably diminishes the value of
critical habitat for the conservation of
the island marble butterfly. Such
alterations may include, but are not
limited to, those that alter the physical
or biological features essential to the
conservation of these species or that
preclude or significantly delay
development of such features. As
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discussed above, the role of critical
habitat is to support physical or
biological features essential to the
conservation of a listed species and
provide for the conservation of the
species.
Section 4(b)(8) of the Act requires us
to briefly evaluate and describe, in any
proposed or final regulation that
designates critical habitat, activities
involving a Federal action that may
destroy or adversely modify such
habitat, or that may be affected by such
designation.
Activities that may affect critical
habitat, when carried out, funded, or
authorized by a Federal agency, should
result in consultation for the island
marble butterfly. These activities
include, but are not limited to:
(1) Actions that destroy the habitat
within the critical habitat unit. Such
activities could include, but are not
limited to, new infrastructure
developments, planting forests in
historical prairie, or large paving
projects. These activities could disrupt
dispersal, mate finding, and patchy
population dynamics, as well as prevent
the recruitment of future habitat.
(2) Actions that would temporarily or
permanently remove host plants from
areas within the critical habitat unit that
were otherwise phenologically and
spatially available for use by the
species. Such activities could include,
but are not limited to, mowing, burning,
or applying herbicide to host plants
leading up to or during the flight season.
These activities could reduce the
quantity or distribution of oviposition
sites available to the species.
(3) Actions that would temporarily or
permanently remove nectar resources or
plants used for mate finding from areas
within the critical habitat unit that were
otherwise phenologically and spatially
available for use by the species. Such
activities could include, but are not
limited to, mowing, burning, or
applying herbicide to nectar or matefinding plants leading up to or during
the flight season. These activities could
reduce nectaring opportunities or
disrupt mate finding, both of which
could reduce fecundity.
(4) Actions that would physically
disturb appropriate areas for diapause
and pupation. Such activities could
include, but are not limited to, mowing,
trampling, grazing, or burning between
flight seasons. These activities could
also kill island marble butterflies in
diapause as pupae.
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Exemptions
Application of Section 4(a)(3) of the Act
Section 4(a)(3)(B)(i) of the Act (16
U.S.C. 1533(a)(3)(B)(i)) provides that:
‘‘The Secretary shall not designate as
critical habitat any lands or other
geographical areas owned or controlled
by the Department of Defense, or
designated for its use, that are subject to
an integrated natural resources
management plan [INRMP] prepared
under section 101 of the Sikes Act (16
U.S.C. 670a), if the Secretary determines
in writing that such plan provides a
benefit to the species for which critical
habitat is proposed for designation.’’
There are no Department of Defense
(DoD) lands with a completed INRMP
within the final critical habitat
designation.
Consideration of Impacts Under Section
4(b)(2) of the Act
Section 4(b)(2) of the Act states that
the Secretary shall designate and make
revisions to critical habitat on the basis
of the best available scientific data after
taking into consideration the economic
impact, national security impact, and
any other relevant impact of specifying
any particular area as critical habitat.
The Secretary may exclude an area from
critical habitat if he determines that the
benefits of such exclusion outweigh the
benefits of specifying such area as part
of the critical habitat, unless he
determines, based on the best scientific
data available, that the failure to
designate such area as critical habitat
will result in the extinction of the
species. In making that determination,
the statute on its face, as well as the
legislative history are clear that the
Secretary has broad discretion regarding
which factor(s) to use and how much
weight to give to any factor.
Consideration of Economic Impacts
Section 4(b)(2) of the Act and its
implementing regulations require that
we consider the economic impact that
may result from a designation of critical
habitat. In order to consider economic
impacts, we prepared an incremental
effects memorandum (IEM) and
screening analysis, which, together with
our narrative and interpretation of
effects, we consider our draft economic
analysis (DEA) of the proposed critical
habitat designation and related factors.
The DEA was made available for public
review and comment concurrently with
the April 12, 2018, proposed rule
(Industrial Economics, Incorporated
2017). The DEA addresses probable
economic impacts of the critical habitat
designation for island marble butterfly.
No additional information was
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submitted during the comment period
that pertained to our consideration of
the probable incremental economic
impacts of this critical habitat
designation. Additional information
relevant to the probable incremental
economic impacts of critical habitat
designation for the island marble
butterfly is summarized below and
available in the screening analysis for
the island marble butterfly (Industrial
Economics, Incorporated 2017),
available at https://www.regulations.gov.
The critical habitat designation for the
island marble butterfly is comprised of
a single unit and is considered
occupied. The critical habitat
designation consists of 812 ac (329 ha)
and is owned and managed by NPS,
BLM, DHS, WDNR, San Juan County,
and private landowners. In these areas,
any actions that may affect the species
or its habitat would also affect
designated critical habitat, and it is
unlikely that any additional
conservation efforts will be
recommended to address the adverse
modification standard over and above
those recommended as necessary to
avoid jeopardizing the continued
existence of the island marble butterfly.
Therefore, the potential incremental
economic impacts of the island marble
butterfly critical habitat designation are
expected to be limited to administrative
costs. We anticipate that the
incremental administrative costs of
addressing adverse modification of the
island marble butterfly critical habitat in
a section 7 consultation will be minor.
Total annualized incremental costs of
critical habitat designation for the island
marble butterfly are anticipated to be
less than $150,000 over the next 20
years, or approximately $10,000
annually. The incremental
administrative burden resulting from
the designation of critical habitat for the
island marble butterfly is not
anticipated to reach $100 million in any
given year based on the anticipated
annual number of consultations and
associated consultation costs, which are
not expected to exceed $10,000 in most
years.
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Exclusions
Exclusions Based on Economic Impacts
The Service considered the economic
impacts of the critical habitat
designation and the Secretary is not
exercising his discretion to exclude any
areas from this designation of critical
habitat for the island marble butterfly
based on economic impacts.
A copy of the IEM and screening
analysis with supporting documents
may be obtained by contacting the
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Washington Fish and Wildlife Office
(see FOR FURTHER INFORMATION CONTACT)
or by downloading from the internet at
https://www.regulations.gov.
Exclusions Based on Impacts on
National Security and Homeland
Security
Section 4(a)(3)(B)(i) of the Act may
not cover all DoD lands or areas that
pose potential national-security
concerns (e.g., a DoD installation that is
in the process of revising its INRMP for
a newly listed species or a species
previously not covered). If a particular
area is not covered under section
4(a)(3)(B)(i) of the Act, national-security
or homeland-security concerns are not a
factor in the process of determining
what areas meet the definition of
‘‘critical habitat.’’ Nevertheless, when
designating critical habitat under
section 4(b)(2), the Service must
consider impacts on national security,
including homeland security, on lands
or areas not covered by section
4(a)(3)(B)(i) of the Act. Accordingly, we
will always consider for exclusion from
the designation areas for which DoD,
Department of Homeland Security
(DHS), or another Federal agency has
requested exclusion based on an
assertion of national-security or
homeland-security concerns.
We cannot, however, automatically
exclude requested areas. When DoD,
DHS, or another Federal agency requests
exclusion from critical habitat on the
basis of national-security or homelandsecurity impacts, it must provide a
reasonably specific justification of an
incremental impact on national security
that would result from the designation
of that specific area as critical habitat.
That justification could include
demonstration of probable impacts,
such as impacts to ongoing bordersecurity patrols and surveillance
activities, or a delay in training or
facility construction, as a result of
compliance with section 7(a)(2) of the
Act. If the agency requesting the
exclusion does not provide us with a
reasonably specific justification, we will
contact the agency to recommend that it
provide a specific justification or
clarification of its concerns relative to
the probable incremental impact that
could result from the designation. If the
agency provides a reasonably specific
justification, we will defer to the expert
judgment of DoD, DHS, another Federal
agency as to: (1) Whether activities on
its lands or waters, or its activities on
other lands or waters, have nationalsecurity or homeland-security
implications; (2) the importance of those
implications; and (3) the degree to
which the cited implications would be
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26815
adversely affected in the absence of an
exclusion. In that circumstance, in
conducting a discretionary 4(b)(2)
exclusion analysis, we will give great
weight to national-security and
homeland-security concerns in
analyzing the benefits of exclusion.
Department of Homeland Security
currently owns 5 ac (2 ha) of land that
is surrounded by land owned and
managed by BLM and lies within the
critical habitat boundary. Specifically,
these lands include a lighthouse facility
that is managed by the U.S. Coast
Guard. The U.S. Coast Guard is in the
process of transferring ownership of
these lands to BLM; therefore, we
anticipate no impact on national
security from the inclusion of these
lands in the critical habitat designation.
Consequently, the Secretary is not
intending to exercise his discretion to
exclude any areas from the final
designation based on impacts on
national security.
Exclusions Based on Other Relevant
Impacts
Under section 4(b)(2) of the Act, we
consider any other relevant impacts, in
addition to economic impacts and
impacts on national security. We
consider a number of factors including
whether there are permitted
conservation plans covering the species
in the area such as HCPs, safe harbor
agreements, or candidate conservation
agreements with assurances (CCAA), or
whether there are non-permitted
conservation agreements and
partnerships that would be encouraged
by designation of, or exclusion from,
critical habitat. In addition, we look at
the existence of tribal conservation
plans and partnerships and consider the
government-to-government relationship
of the United States with tribal entities.
We also consider any social impacts that
might occur because of the designation.
In preparing this final rule, we have
determined that there are currently no
non-permitted conservation agreements
or partnerships for the island marble
butterfly. There is a CCAA which is
designed to provide non-federal
landowners with the opportunity to
create and maintain habitat for the
island marble butterfly while providing
incidental take coverage and regulatory
certainty. The final designation does not
include any tribal lands or tribal trust
resources. We anticipate no impact on
tribal lands, partnerships, permitted or
non-permitted plans or agreements from
this critical habitat designation.
Accordingly, the Secretary is not
exercising his discretion to exclude any
areas from this final designation based
on other relevant impacts.
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Required Determinations
Regulatory Planning and Review
(Executive Orders 12866 and 13563)
Executive Order 12866 provides that
the Office of Information and Regulatory
Affairs (OIRA) will review all significant
rules. The Office of Information and
Regulatory Affairs has determined that
this rule is not significant.
Executive Order 13563 reaffirms the
principles of E.O. 12866 while calling
for improvements in the nation’s
regulatory system to promote
predictability, to reduce uncertainty,
and to use the best, most innovative,
and least burdensome tools for
achieving regulatory ends. The
executive order directs agencies to
consider regulatory approaches that
reduce burdens and maintain flexibility
and freedom of choice for the public
where these approaches are relevant,
feasible, and consistent with regulatory
objectives. E.O. 13563 emphasizes
further that regulations must be based
on the best available science and that
the rulemaking process must allow for
public participation and an open
exchange of ideas. We have developed
this rule in a manner consistent with
these requirements.
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Executive Order 13771
This rule is not an E.O. 13771
(‘‘Reducing Regulation and Controlling
Regulatory Costs’’) (82 FR 9339,
February 3, 2017) regulatory action
because this rule is not significant under
E.O. 12866.
Regulatory Flexibility Act (5 U.S.C. 601
et seq.)
Under the Regulatory Flexibility Act
(RFA; 5 U.S.C. 601 et seq.), as amended
by the Small Business Regulatory
Enforcement Fairness Act of 1996
(SBREFA; 5 U.S.C. 801 et seq.),
whenever an agency is required to
publish a notice of rulemaking for any
proposed or final rule, it must prepare
and make available for public comment
a regulatory flexibility analysis that
describes the effects of the rule on small
entities (i.e., small businesses, small
organizations, and small government
jurisdictions). However, no regulatory
flexibility analysis is required if the
head of the agency certifies the rule will
not have a significant economic impact
on a substantial number of small
entities. The SBREFA amended the RFA
to require Federal agencies to provide a
certification statement of the factual
basis for certifying that the rule will not
have a significant economic impact on
a substantial number of small entities.
According to the Small Business
Administration, small entities include
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small organizations such as
independent nonprofit organizations;
small governmental jurisdictions,
including school boards and city and
town governments that serve fewer than
50,000 residents; and small businesses
(13 CFR 121.201). Small businesses
include manufacturing and mining
concerns with fewer than 500
employees, wholesale trade entities
with fewer than 100 employees, retail
and service businesses with less than $5
million in annual sales, general and
heavy construction businesses with less
than $27.5 million in annual business,
special trade contractors doing less than
$11.5 million in annual business, and
agricultural businesses with annual
sales less than $750,000. To determine
if potential economic impacts to these
small entities are significant, we
considered the types of activities that
might trigger regulatory impacts under
this designation as well as types of
project modifications that may result. In
general, the term ‘‘significant economic
impact’’ is meant to apply to a typical
small business firm’s business
operations.
The Service’s current understanding
of the requirements under the RFA, as
amended, and following recent court
decisions, is that Federal agencies are
only required to evaluate the potential
incremental impacts of rulemaking on
those entities directly regulated by the
rulemaking itself, and are, therefore, not
required to evaluate the potential
impacts to indirectly regulated entities.
The regulatory mechanism through
which critical habitat protections are
realized is section 7 of the Act, which
requires Federal agencies, in
consultation with the Service, to ensure
that any action authorized, funded, or
carried out by the agency is not likely
to destroy or adversely modify critical
habitat. Therefore, under section 7, only
Federal action agencies are directly
subject to the specific regulatory
requirement (avoiding destruction and
adverse modification) imposed by
critical habitat designation.
Consequently, it is our position that
only Federal action agencies will be
directly regulated by this designation.
There is no requirement under the RFA
to evaluate the potential impacts to
entities not directly regulated.
Moreover, Federal agencies are not
small entities. Therefore, because no
small entities are directly regulated by
this rulemaking, the Service certifies
that the final critical habitat designation
will not have a significant economic
impact on a substantial number of small
entities.
During the development of this final
rule, we reviewed and evaluated all
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information submitted during the
comment period that may pertain to our
consideration of the probable
incremental economic impacts of this
critical habitat designation. Based on
this information, we affirm our
certification that this final critical
habitat designation will not have a
significant economic impact on a
substantial number of small entities,
and a regulatory flexibility analysis is
not required.
Energy Supply, Distribution, or Use—
Executive Order 13211
Executive Order 13211 (Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use) requires agencies
to prepare Statements of Energy Effects
when undertaking certain actions. OMB
has provided guidance for
implementing this Executive Order that
outlines nine outcomes that may
constitute ‘‘a significant adverse effect’’
when compared to not taking the
regulatory action under consideration.
The economic analysis finds that none
of these criteria is relevant to this
analysis. Thus, based on information in
the economic analysis, energy-related
impacts associated with island marble
butterfly conservation activities within
critical habitat are not expected. As
such, the designation of critical habitat
is not expected to significantly affect
energy supplies, distribution, or use.
Therefore, this action is not a significant
energy action, and no Statement of
Energy Effects is required.
Unfunded Mandates Reform Act (2
U.S.C. 1501 et seq.)
In accordance with the Unfunded
Mandates Reform Act (2 U.S.C. 1501 et
seq.), we make the following findings:
(1) This rule will not produce a
Federal mandate. In general, a Federal
mandate is a provision in legislation,
statute, or regulation that would impose
an enforceable duty upon State, local, or
tribal governments, or the private sector,
and includes both ‘‘Federal
intergovernmental mandates’’ and
‘‘Federal private sector mandates.’’
These terms are defined in 2 U.S.C.
658(5)–(7). ‘‘Federal intergovernmental
mandate’’ includes a regulation that
‘‘would impose an enforceable duty
upon State, local, or tribal governments’’
with two exceptions. It excludes ‘‘a
condition of Federal assistance.’’ It also
excludes ‘‘a duty arising from
participation in a voluntary Federal
program,’’ unless the regulation ‘‘relates
to a then-existing Federal program
under which $500,000,000 or more is
provided annually to State, local, and
tribal governments under entitlement
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authority,’’ if the provision would
‘‘increase the stringency of conditions of
assistance’’ or ‘‘place caps upon, or
otherwise decrease, the Federal
Government’s responsibility to provide
funding,’’ and the State, local, or tribal
governments ‘‘lack authority’’ to adjust
accordingly. At the time of enactment,
these entitlement programs were:
Medicaid; Aid to Families with
Dependent Children work programs;
Child Nutrition; Food Stamps; Social
Services Block Grants; Vocational
Rehabilitation State Grants; Foster Care,
Adoption Assistance, and Independent
Living; Family Support Welfare
Services; and Child Support
Enforcement. ‘‘Federal private sector
mandate’’ includes a regulation that
‘‘would impose an enforceable duty
upon the private sector, except (i) a
condition of Federal assistance or (ii) a
duty arising from participation in a
voluntary Federal program.’’
The designation of critical habitat
does not impose a legally binding duty
on non-Federal Government entities or
private parties. Under the Act, the only
regulatory effect is that Federal agencies
must ensure that their actions do not
destroy or adversely modify critical
habitat under section 7. While nonFederal entities that receive Federal
funding, assistance, or permits, or that
otherwise require approval or
authorization from a Federal agency for
an action, may be indirectly impacted
by the designation of critical habitat, the
legally binding duty to avoid
destruction or adverse modification of
critical habitat rests squarely on the
Federal agency. Furthermore, to the
extent that non-Federal entities are
indirectly impacted because they
receive Federal assistance or participate
in a voluntary Federal aid program, the
Unfunded Mandates Reform Act would
not apply, nor would critical habitat
shift the costs of the large entitlement
programs listed above onto State
governments.
(2) We do not believe that this rule
will significantly or uniquely affect
small governments because the area
included in the critical habitat
designation is largely owned by Federal
and State agencies (greater than 95
percent). None of these government
entities fits the definition of ‘‘small
government jurisdiction.’’
Consequently, we do not believe that
the critical habitat designation would
significantly or uniquely affect small
government entities. As such, a Small
Government Agency Plan is not
required.
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Takings—Executive Order 12630
In accordance with E.O. 12630
(Government Actions and Interference
with Constitutionally Protected Private
Property Rights), we have analyzed the
potential takings implications of
designating critical habitat for the island
marble butterfly in a takings
implications assessment. The Act does
not authorize the Service to regulate
private actions on private lands or
confiscate private property as a result of
critical habitat designation. Designation
of critical habitat does not affect land
ownership, or establish any closures or
restrictions on use of or access to the
designated areas. Furthermore, the
designation of critical habitat does not
affect landowner actions that do not
require Federal funding or permits, nor
does it preclude development of habitat
conservation programs or issuance of
incidental take permits to permit actions
that do require Federal funding or
permits to go forward. However, Federal
agencies are prohibited from carrying
out, funding, or authorizing actions that
would destroy or adversely modify
critical habitat. A takings implications
assessment has been completed and
concludes that this designation of
critical habitat for the island marble
butterfly does not pose significant
takings implications for lands within or
affected by the designation.
Federalism—Executive Order 13132
In accordance with E.O. 13132
(Federalism), this rule does not have
significant federalism effects. A
federalism summary impact statement is
not required. In keeping with
Department of the Interior and
Department of Commerce policy, we
requested information from, and
coordinated development of this critical
habitat designation with, appropriate
State resource agencies in Washington.
We did not receive comments from
Washington Department of Fish and
Wildlife. From a federalism perspective,
the designation of critical habitat
directly affects only the responsibilities
of Federal agencies. The Act imposes no
other duties with respect to critical
habitat, either for States and local
governments, or for anyone else. As a
result, the rule does not have substantial
direct effects either on the States, or on
the relationship between the national
government and the States, or on the
distribution of powers and
responsibilities among the various
levels of government. The designation
may have some benefit to these
governments because the areas that
contain the features essential to the
conservation of the species are more
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26817
clearly defined, and the physical and
biological features of the habitat
necessary to the conservation of the
species are specifically identified. This
information does not alter where and
what federally sponsored activities may
occur. However, it may assist these local
governments in long-range planning
(because these local governments no
longer have to wait for case-by-case
section 7 consultations to occur).
Where State and local governments
require approval or authorization from a
Federal agency for actions that may
affect critical habitat, consultation
under section 7(a)(2) will be required.
While non-Federal entities that receive
Federal funding, assistance, or permits,
or that otherwise require approval or
authorization from a Federal agency for
an action, may be indirectly impacted
by the designation of critical habitat, the
legally binding duty to avoid
destruction or adverse modification of
critical habitat rests squarely on the
Federal agency.
Civil Justice Reform—Executive Order
12988
In accordance with Executive Order
12988 (Civil Justice Reform), the Office
of the Solicitor has determined that the
rule does not unduly burden the judicial
system and that it meets the applicable
standards set forth in sections 3(a) and
3(b)(2) of the Order. We are designating
critical habitat in accordance with the
provisions of the Act. To assist the
public in understanding the habitat
needs of the species, the rule identifies
the elements of physical or biological
features essential to the conservation of
the island marble butterfly. The
designated areas of critical habitat are
presented on maps, and the rule
provides several options for the
interested public to obtain more
detailed location information, if desired.
Paperwork Reduction Act of 1995 (44
U.S.C. 3501 et seq.)
This rule does not contain any new
collections of information that require
approval by the Office of Management
and Budget (OMB) under the Paperwork
Reduction Act of 1995 (44 U.S.C. 3501
et seq.). An agency may not conduct or
sponsor, and a person is not required to
respond to, a collection of information
unless it displays a currently valid OMB
control number.
National Environmental Policy Act (42
U.S.C. 4321 et seq.)
We have determined that
environmental assessments and
environmental impact statements, as
defined under the authority of the
National Environmental Policy Act
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(NEPA; 42 U.S.C. 4321 et seq.), need not
be prepared in connection with listing
a species as an endangered or
threatened species under the
Endangered Species Act. We published
a notice outlining our reasons for this
determination in the Federal Register
on October 25, 1983 (48 FR 49244).
It is our position that, outside the
jurisdiction of the U.S. Court of Appeals
for the Tenth Circuit, we do not need to
prepare environmental analyses
pursuant to NEPA in connection with
designating critical habitat under the
Act. We published a notice outlining
our reasons for this determination in the
Federal Register on October 25, 1983
(48 FR 49244). This position was upheld
by the U.S. Court of Appeals for the
Ninth Circuit (Douglas County v.
Babbitt, 48 F.3d 1495 (9th Cir. 1995),
cert. denied 516 U.S. 1042 (1996)).
Government-to-Government
Relationship With Tribes
In accordance with the President’s
memorandum of April 29, 1994
(Government-to-Government Relations
with Native American Tribal
Governments; 59 FR 22951), Executive
Order 13175 (Consultation and
Coordination with Indian Tribal
Governments), and the Department of
the Interior’s manual at 512 DM 2, we
readily acknowledge our responsibility
Common name
to communicate meaningfully with
recognized Federal Tribes on a
government-to-government basis. In
accordance with Secretarial Order 3206
of June 5, 1997 (American Indian Tribal
Rights, Federal-Tribal Trust
Responsibilities, and the Endangered
Species Act), we readily acknowledge
our responsibilities to work directly
with tribes in developing programs for
healthy ecosystems, to acknowledge that
tribal lands are not subject to the same
controls as Federal public lands, to
remain sensitive to Indian culture, and
to make information available to tribes.
We determined that there are no tribal
lands occupied by the island marble
butterfly at the time of listing that
contain the physical or biological
features essential to conservation of the
species, and no tribal lands unoccupied
by the island marble butterfly that are
essential for the conservation of the
species. Therefore, we are not
designating critical habitat for the island
marble butterfly on tribal lands.
References Cited
A complete list of references cited in
this rulemaking is available on the
internet at https://www.regulations.gov
and upon request from the Washington
Fish and Wildlife Office (see FOR
FURTHER INFORMATION CONTACT).
Scientific name
*
*
Where listed
*
The primary authors of this final rule
are the staff members of the Washington
Fish and Wildlife Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species,
Exports, Imports, Reporting and
recordkeeping requirements,
Transportation.
Regulation Promulgation
Accordingly, we amend part 17,
subchapter B of chapter I, title 50 of the
Code of Federal Regulations, as set forth
below:
PART 17—ENDANGERED AND
THREATENED WILDLIFE AND PLANTS
1. The authority citation for part 17
continues to read as follows:
■
Authority: 16 U.S.C. 1361–1407; 1531–
1544; and 4201–4245, unless otherwise
noted.
2. Amend § 17.11(h) by adding an
entry for ‘‘Butterfly, island marble’’ to
the List of Endangered and Threatened
Wildlife in alphabetical order under
‘‘INSECTS’’ to read as follows:
■
§ 17.11 Endangered and threatened
wildlife.
*
Status
*
Authors
*
*
(h) * * *
*
*
Listing citations and applicable rules
*
*
*
INSECTS
*
Butterfly, island marble ...
*
*
Euchloe ausonides
insulanus.
*
3. In § 17.95, amend paragraph (i) by
adding an entry for ‘‘Island Marble
Butterfly (Euchloe ausonides
insulanus)’’ in the same alphabetical
order that the species appears in the
table at § 17.11(h), to read as follows:
Critical habitat—fish and wildlife.
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*
*
*
(i) Insects.
*
*
*
*
*
*
*
Island Marble Butterfly (Euchloe
ausonides insulanus)
(1) The critical habitat unit is
depicted for San Juan County,
Washington, on the map below.
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*
Wherever found ..............
*
■
§ 17.95
*
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*
*
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*
*
85 FR [insert Federal Register page where the
document begins], 5/5/2020; 50 CFR 17.95(i).CH
*
(2) Within the critical habitat area on
San Juan Island, Washington, the
physical or biological features essential
to the conservation of the island marble
butterfly consist of the following
components:
(i) Open, primarily treeless areas with
short-statured forb- and grass-dominated
vegetation that include diverse
topographic features such as ridgelines,
hills, and bluffs for patrolling, dispersal
corridors between habitat patches, and
some south-facing terrain. Areas must
be large enough to allow for the
development of patchy-population
dynamics, allowing for multiple small
populations to establish within the area.
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*
*
(ii) Low- to medium-density larval
host plants, with both flower buds and
blooms on them between the months of
May through July, for egg-laying and
larval development. Larval host plants
may be any of the following: Brassica
rapa, Sisymbrium altissimum, or
Lepidium virginicum.
(iii) Adult nectar resources in flower
and short-statured, white-flowering
plants in bloom used for mate-finding,
which may include, but are not limited
to, Abronia latifolia (yellow sand
verbena), Achillea millefolium (yarrow),
Amsinckia menziesii (small-flowered
fiddleneck), Cakile edentula (American
sea rocket), Cerastium arvense (field
chickweed), Erodium cicutarium
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(common stork’s bill), Geranium molle
(dovefoot geranium), Hypochaeris
radicata (hairy cat’s ear), Lomatium
utriculatum (common lomatium),
Lupinus littoralis (seashore lupine),
Myosotis discolor (common forget-menot), Ranunculus californicus
(California buttercup), Rubus ursinus
(trailing blackberry), Taraxacum
officinale (dandelion), Toxicoscordion
venenosum (death camas, formerly
known as Zigadenus venenosus), and
Triteleia grandiflora (Howell’s brodiaea,
formerly Brodiaea howellii).
(iv) Areas of undisturbed vegetation
surrounding larval host plants sufficient
to provide secure sites for diapause and
pupation. The vegetation surrounding
larval host plants must be left standing
for a sufficient period of time for the
island marble butterfly to complete its
life cycle.
(3) Critical habitat includes road
shoulders and road margins, but does
not include other manmade structures
(such as buildings, aqueducts, runways,
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19:34 May 04, 2020
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paved portions of roads, and other
paved areas) and the land on which they
are located existing within the legal
boundaries on June 4, 2020.
(4) Critical habitat map unit. Data
layers defining the map were created
using 2015 National Agriculture
Imagery Program (NAIP) digital imagery
in ArcGIS, version 10.4 (Environmental
Systems Research Institute, Inc.), a
computer geographic information
system program. The map in this entry,
as modified by any accompanying
regulatory text, establishes the
boundaries of the critical habitat
designation. The coordinates or plot
points or both on which the map is
based are available to the public at the
Service’s internet site at https://
www.fws.gov/wafwo/, at https://
www.regulations.gov at Docket No.
FWS–R1–ES–2016–0145, and at the
field office responsible for this
designation. You may obtain field office
location information by contacting one
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26819
of the Service regional offices, the
addresses of which are listed at 50 CFR
2.2.
(5) Island marble butterfly critical
habitat, San Juan County, Washington.
(i) Island marble butterfly critical
habitat consists of 812 acres (ac) (329
hectares (ha)) on San Juan Island in San
Juan County, Washington, and is
composed of lands in Federal (742 ac
(301 ha)), State (37 ac (15 ha)), State/
County joint (1 ac (0.4 ha)), County (30
ac (12 ha)), and private (2 ac (0.8 ha))
ownership. The critical habitat
designated on private parcels along
Eagle Cove only includes the area of
steep coastal bluff between the marine
shoreline and the upland edge at the top
of the bluff; it does not include areas
landward of the top of the bluff, which
are typically mowed and maintained as
yard.
(ii) Map of island marble butterfly
critical habitat follows:
BILLING CODE 433–15–P
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*
Federal Register / Vol. 85, No. 87 / Tuesday, May 5, 2020 / Rules and Regulations
*
*
Signed:
Aurelia Skipwith,
Director, U.S. Fish and Wildlife Service.
*
BILLING CODE 4333–15–C
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[FR Doc. 2020–07856 Filed 5–4–20; 8:45 am]
]]>Agencies
[Federal Register Volume 85, Number 87 (Tuesday, May 5, 2020)]
[Rules and Regulations]
[Pages 26786-26820]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-07856]
[[Page 26785]]
Vol. 85
Tuesday,
No. 87
May 5, 2020
Part II
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Endangered Status for
the Island Marble Butterfly and Designation of Critical Habitat; Final
Rule
Federal Register / Vol. 85 , No. 87 / Tuesday, May 5, 2020 / Rules
and Regulations
[[Page 26786]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R1-ES-2016-0145; FF09E21000 FXES11110900000 201]
RIN 1018-BB96
Endangered and Threatened Wildlife and Plants; Endangered Status
for the Island Marble Butterfly and Designation of Critical Habitat
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
endangered species status under the Endangered Species Act of 1973
(Act), as amended, for the island marble butterfly (Euchloe ausonides
insulanus) and designate critical habitat. In total, approximately 812
acres (329 hectares) on the south end of San Juan Island, San Juan
County, Washington, fall within the boundaries of the critical habitat
designation.
DATES: This rule is effective June 4, 2020.
ADDRESSES: This final rule is available on the internet at https://www.regulations.gov. Comments and materials we received, as well as
supporting documentation we used in preparing this rule, are available
for public inspection at https://www.regulations.gov at Docket No. FWS-
R1-ES-2016-0145. Comments, materials, and documentation that we
considered in this rulemaking will be available by appointment, during
normal business hours at: U.S. Fish and Wildlife Service, Washington
Fish and Wildlife Office, 510 Desmond Drive, Suite 102, Lacey, WA
98503; telephone 360-753-9440.
The coordinates or plot points or both from which the maps are
generated are included in the administrative record for this critical
habitat designation and are available at https://www.regulations.gov at
Docket No. FWS-R1-ES-2016-0145, on the Service's website at https://www.fws.gov/wafwo/,and at the Washington Fish and Wildlife Office
(address provided above). Any additional tools or supporting
information that we developed for this critical habitat designation
will also be available at the Fish and Wildlife Service website and
Field Office set out above, and may also be included in the preamble
and at https://www.regulations.gov.
FOR FURTHER INFORMATION CONTACT: Brad Thompson, Acting State
Supervisor, Washington Fish and Wildlife Office, 510 Desmond Drive,
Suite 102, Lacey, WA 98503; telephone 360-753-9440. Persons who use a
telecommunications device for the deaf (TDD) may call the Federal Relay
Service at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Endangered Species Act, a
species may warrant protection through listing if it is endangered or
threatened throughout all or a significant portion of its range.
Listing a species as an endangered or threatened species can only be
completed by issuing a rule. Further, under the Endangered Species Act,
any species that is determined to be an endangered or threatened
species requires critical habitat to be designated, to the maximum
extent prudent and determinable. Designations and revisions of critical
habitat can only be completed by issuing a rule.
What this document does. This rule lists the island marble
butterfly (Euchloe ausonides insulanus) as an endangered species and
designates critical habitat for this species under the Endangered
Species Act. We are designating critical habitat for the species in one
unit, on public and private property totaling 812 acres (329 hectares)
on San Juan Island, San Juan County, Washington.
The basis for our action. Under the Endangered Species Act, we can
determine that a species is an endangered or threatened species based
on any of five factors: (A) The present or threatened destruction,
modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or
educational purposes; (C) disease or predation; (D) the inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. We have determined that the island
marble butterfly faces the following threats:
Habitat loss and degradation from plant succession and
invasion by plants that displace larval host plants; browsing by black-
tailed deer, European rabbits, and brown garden snails; and storm
surges;
Predation by native spiders and nonnative wasps, and
incidental predation by black-tailed deer; and
Vulnerabilities associated with small population size and
environmental and demographic stochasticity, and other chance events
that increase mortality or reduce reproductive success.
Existing regulatory mechanisms and conservation efforts do not
address these threats to the island marble butterfly to the extent that
listing is not warranted.
This rule also designates critical habitat for the island marble
butterfly in accordance with the Endangered Species Act. The critical
habitat areas we are designating in this rule constitute our current
best assessment of the areas that meet the definition of critical
habitat for the island marble butterfly.
Economic analysis. We prepared an economic analysis of the impacts
of designating critical habitat. We made the draft economic analysis
available for public comments on April 12, 2018 (83 FR 15900). The
analysis found no significant economic impact of the designation of
critical habitat.
Peer review and public comment. We sought comments from five
independent specialists to ensure that our species determination and
critical habitat designation are based on scientifically sound data,
assumptions, and analyses. We obtained opinions from two knowledgeable
individuals with scientific expertise to review our technical
assumptions and analysis, and whether or not we had used the best
scientific data available. These peer reviewers generally concurred
with our methods and conclusions, and provided additional information,
clarification, and suggestions to improve this final rule. Information
we received from peer review is incorporated into this final rule. We
also considered all comments and information we received from the
public during the comment period for the proposed listing and the
proposed designation of critical habitat.
Previous Federal Actions
On April 12, 2018, we published in the Federal Register a proposed
rule (83 FR 15900) to list the island marble butterfly as an endangered
species and to designate critical habitat for the species under the
Endangered Species Act of 1973 (Act), as amended (16 U.S.C. 1531 et
seq.). Please refer to that proposed rule for a detailed description of
Federal actions concerning the island marble butterfly that occurred
prior to the proposal's publication.
Summary of Changes From the Proposed Rule
Based on information we received from peer reviewers and public
commenters, in this rule, we make the following changes from our April
12, 2018, proposed rule (83 FR 15900):
(1) We describe habitat use by the island marble butterfly to
better reflect
[[Page 26787]]
that the organism exhibits ``patchy'' population dynamics at the local
scale rather than following a classic metapopulation dynamic model;
(2) We indicate that the island marble butterfly has been observed
flying on lands immediately adjacent to the American Camp unit of San
Juan Island National Historical Park (SJINHP);
(3) We update portions of the rule to reflect the most current
information regarding captive rearing and monitoring;
(4) We indicate that while female island marble butterflies tend to
use a single host plant species in each of three specific habitat
types, there are instances (for example, when host plants are scarce)
when they will use another of the three known host plant species in a
specific habitat type;
(5) We revise the description of the time that island marble
butterflies spend as winged adults from an estimated average of 6 to 9
days to include the potential to persist as winged adults for up to 16
days, based on documentation provided by two separate commenters;
(6) We include information regarding the aversion male island
marble butterflies have demonstrated for flying over tall vegetation,
including avoiding flying over fields of tall grasses; and
(7) We revise the critical habitat discussion and designation to
address the limitations in the precision of mapped critical habitat, to
clarify that the critical habitat designation includes road shoulders
and road margins, and to clarify our intent to designate as critical
habitat only the steep coastal bluffs on private lands near Eagle Cove.
Summary of Comments and Recommendations
In our April 12, 2018, proposed rule (83 FR 15900), we requested
that all interested parties submit written comments on the proposal by
June 11, 2018. We also contacted appropriate Federal and State
agencies, scientific experts and organizations, and other interested
parties and invited them to comment on the proposed determination,
proposed designation of critical habitat, and draft economic analysis.
Newspaper notices inviting general public comment were published in the
Islands' Sounder, Journal of the San Juans, and the Seattle Times. We
did not receive any requests for a public hearing. All substantive
information provided during the comment period has either been
incorporated directly into this final rule or is addressed below.
During the comment period, we received 23 comment letters
addressing the proposed determination and/or the proposed critical
habitat designation. We address all substantive comments either below
or by making the requested changes to the rule, as described above,
when we determined that they were correct. We did not receive comments
from any Federal agencies or Tribes. We received a letter of support
from the Washington Department of Fish and Wildlife; however, their
letter did not contain any comments or requests for revision of the
language.
Peer Reviewer Comments
In accordance with our peer review policy published on July 1, 1994
(59 FR 34270), we solicited expert opinion from five knowledgeable
individuals with scientific expertise that included familiarity with
the island marble butterfly and its habitat, biological needs, and
threats; the geographic region in which the species occurs; and
conservation biology principles. We received responses from two of the
peer reviewers.
We reviewed all comments we received from the peer reviewers for
substantive issues and new information regarding the island marble
butterfly and its critical habitat. The peer reviewers generally
concurred with our methods and conclusions, and provided additional
information, clarifications, and suggestions to improve the final rule.
Peer reviewer comments are addressed in the following summary and
incorporated into the final rule as appropriate.
(1) Comment: One peer reviewer highlighted the lack of clarity
surrounding what constitutes a ``site,'' both within American Camp and
outside of the park.
Our Response: Due to the way data were collected and submitted to
the Service, we were limited in the way we could reference and analyze
detection or nondetection of the island marble butterfly in any given
year. We assign the term ``site'' to each location that has a name and
survey information associated with it.
(2) Comment: One peer reviewer indicated that describing the island
marble butterfly as having a ``low dispersal capacity'' was inaccurate
and suggested revising the narrative to reflect that the island marble
butterfly exhibits ``patchy population dynamics.''
Our Response: We revised the narrative in this rule to reflect that
the island marble butterfly generally exhibits weak site fidelity and
low to intermediate dispersal capacity, which are key behavioral
components of patchy population dynamics.
(3) Comment: One peer reviewer and one commenter identified
potential suitable habitat for the island marble butterfly in areas
known to be previously occupied and stated that these areas should be
included in critical habitat.
Our Response: We considered all previously occupied areas in the
analysis of proposed critical habitat. For the reasons stated below
under Areas Occupied at the Time of Listing, we are designating
critical habitat only on and around American Camp. We are unable, at
this time, to delineate any specific unoccupied areas that are
essential to the conservation of the island marble butterfly due to the
ephemeral and patchy nature of the species' habitat and our limited
understanding regarding the ideal configuration of habitat, the ideal
size and number of habitat patches, and how these habitat patches may
naturally evolve on the landscape. This does not mean that other areas
are not important or valuable to the recovery of the island marble
butterfly, or that we only need one occupied unit to recover the
species.
Public Comments
(4) Comment: One commenter posited that the decline and
disappearance of the island marble butterfly was caused, in part, by
the decline in traditional harvest of food resources by pre-European
peoples who inhabited the Gulf Islands and the San Juan archipelago
followed by the introduction and establishment of nonnative weedy plant
species.
Our Response: While these factors may have contributed to the
decline of the island marble butterfly and other disturbance-dependent
native butterfly species, we were unable to locate any substantiating
evidence that would support this claim.
Background
Species Information
Taxonomy and Species Description
The island marble butterfly (Euchloe ausonides insulanus) is a
subspecies of the large marble butterfly (E. ausonides) in the Pieridae
family, subfamily Pierinae, which primarily consists of yellow and
white butterflies. The island marble butterfly was formally described
in 2001, by Guppy and Shepard (p. 160) based on 14 specimens collected
between 1859 and 1908 on or near Vancouver Island, British Columbia,
Canada, and is geographically isolated from all other E. ausonides
subspecies. The taxonomic status of the island marble butterfly is not
in dispute. Euchloe ausonides insulanus is recognized as a valid
subspecies by the Integrated Taxonomic Information
[[Page 26788]]
System (ITIS 2015a, entire) based on the phenotypic differences
documented in Guppy and Shepard (2001). In this rule, we use shorthand
for simplicity in referring to the island marble butterfly as a species
because subspecies are treated as species for the purposes of
evaluating taxa for listing under the Act.
Island marble butterflies have a wingspan of approximately 1.75
inches (in) (4.5 centimeters (cm)) (Pyle 2002, p. 142) and are
differentiated from other subspecies of the large marble butterfly by
their larger size and the expanded marbling pattern of yellow and green
on the underside of the hindwings and forewings (Guppy and Shepard
2001, p. 159). Immature stages of the island marble butterfly have
distinctly different coloration and markings from Euchloe ausonides;
specifically, the third and fourth larval instars (instars are the
larval stages between molting events) have a white spiracular stripe (a
stripe that runs along the side of a caterpillar) subtended (bordered
below) by a yellow-green subspiracular stripe and a green-yellow
ventral area, which is different from the stripe colors and patterns
described for E. ausonides (James and Nunnallee 2011, pp. 102-103;
Lambert 2011, p. 15). The island marble butterfly is also behaviorally
distinct; large marble butterflies pupate (enter the final stage of
larval development before transforming into a butterfly) directly on
their larval host plants, whereas the island marble butterflies leave
their host plants to find a suitable pupation site up to 13 feet (ft)
(4 meters (m)) away from their larval host plants (Lambert 2011, p.
19).
Distribution
The island marble butterfly was historically known from just two
areas along the southeastern coast of Vancouver Island, British
Columbia, Canada, based on 14 museum records: The Greater Victoria area
at the southern end of Vancouver Island; and near Nanaimo and on
adjacent Gabriola Island, approximately 56 miles (mi) (90 kilometers
(km)) north of Victoria. The last known specimen of the island marble
butterfly from Canada was collected in 1908 on Gabriola Island, and the
species is now considered extirpated from the province (COSEWIC 2010,
p. 6). Reasons for its disappearance from Canada are unknown.
Hypotheses include increased parasitoid loads (the number of individual
deadly parasites within an individual caterpillar) associated with the
introduction of the cabbage white butterfly (Guppy and Shepard 2001, p.
38) or heavy grazing of natural meadows by cattle and sheep, which
severely depressed its presumed larval food plant (SARA 2015).
After 90 years without a documented occurrence, the island marble
butterfly was rediscovered in 1998 on San Juan Island, San Juan County,
Washington, at least 9 mi (15 km) east of Victoria across the Haro
Strait. Subsequent surveys in suitable habitat across southeastern
Vancouver Island and the Gulf Islands in Canada (see COSEWIC 2010, p.
5), as well as the San Juan Islands and six adjacent counties in the
United States (Whatcom, Skagit, Snohomish, Jefferson, Clallam, and
Island Counties), revealed only two other occupied areas. One of these
occupied areas was centered on San Juan Island and the other on Lopez
Island, which is separated from San Juan Island by just over 0.5 mi (1
km) at its closest point. These occupied areas were eventually
determined to comprise five populations, as described in detail in our
2006 12-month finding (71 FR 66292; November 14, 2006). Since 2006, the
number and distribution of populations has declined. Four of the five
populations that once spanned San Juan and Lopez Islands have not been
detected in recent years, and the species is now observed only in a
single area centered on American Camp, a part of San Juan Island
National Historical Park that is managed by the National Park Service
(NPS). The island marble butterfly has also been sighted using the
lands adjoining or near American Camp; there were observations of
island marble butterflies flying beyond the boundaries of these
adjoining lands in 2015 and 2017 (Potter 2015a, in litt.; Lambert 2018,
in litt.).
No current records exist of any life-history stage of the island
marble butterfly except at or near American Camp at San Juan Island
National Historical Park. Therefore, we consider only American Camp and
the immediately adjacent areas to be occupied at the time of this final
listing.
Survey Effort
Extensive surveys have been conducted in British Columbia, Canada,
since 2001, with an estimated 500 survey hours conducted by
professional surveyors and 2,000 survey hours by volunteer butterfly
enthusiasts (COSEWIC 2010, p. v). During these surveys, neither the
island marble butterfly nor suitable habitat was detected (COSEWIC
2010, p. vi). The species has been considered extirpated in British
Columbia since 1910, and was formally designated extirpated in 1999 by
the Canadian government (COSEWIC 2000, p. iii).
In the United States, surveys for the island marble butterfly have
also been extensive. In 2005 and 2006, we partnered with NPS,
Washington Department of Fish and Wildlife (WDFW), Washington
Department of Natural Resources (WDNR), the University of Washington,
and the Xerces Society to survey for the presence of the island marble
butterfly during the adult flight period (when eggs are laid and larvae
are active; early April-late June). Qualified surveyors conducted
approximately 335 individual surveys at more than 160 sites in
potentially suitable habitat across 6 counties (Clallam, Jefferson,
Island, San Juan, Skagit, and Whatcom Counties) and on 16 islands
(Miskelly and Potter 2005, pp. 5, 7-16; Miskelly and Fleckenstein 2007,
pp. 4, 10-19). Outside of American Camp, sites were defined primarily
by ownership, although some exceptionally large sites were subdivided
and received unique site names. All surveys followed a set of
standardized protocols to ensure they were conducted when butterflies
had the highest likelihood of being detected (see Miskelly and Potter
2005, p. 4). Island marble butterflies were considered present at sites
where eggs, larvae, or adults of the species were detected. These
surveys documented five populations distributed across San Juan and
Lopez Islands, including the single population persisting today
centered on American Camp (Miskelly and Fleckenstein 2007, pp. 4-5).
Annual surveys conducted outside of American Camp from 2007-2012
focused on areas with suitable habitat on San Juan and Lopez Islands.
These surveys generally included previously occupied sites, when
accessible, in order to document whether or not island marble
butterflies persisted at the sites where they were detected in 2005 and
2006. After years of observing a rangewide decline in available island
marble butterfly habitat and dwindling island marble butterfly
detections, WDFW determined that there was not enough suitable habitat
remaining outside of American Camp to warrant continued widespread
survey efforts on San Juan and Lopez Islands. Therefore, surveys in
2013 and 2014 focused solely on assisting with monitoring at American
Camp and surveying lands directly adjacent to the park (Potter 2015a in
litt.). Surveys to monitor the status of the population centered on
American Camp have been conducted annually from 2004 to 2015, although
the effort has varied through time (see ``Abundance,'' below, for
additional information).
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In 2015, in addition to annual population monitoring at American
Camp, the Service funded an extensive survey of sites on San Juan
Island outside of American Camp. Areas surveyed included those sites
where island marble butterflies had previously been detected, as well
as areas with suitable habitat with no prior detections. Researchers
conducted 134 individual surveys at a total of 48 sites, including 24
sites where the island marble butterfly had been documented previously.
The survey yielded no detections of the island marble butterfly outside
of American Camp.
Multiple years of extensive surveys conducted across formerly
occupied sites have failed to detect the species. However, it is
possible that the island marble butterfly continues to exist at a
handful of small isolated sites where surveyors were not granted access
or were unable to survey during suitable conditions (Miskelly and
Potter 2005, entire; Miskelly and Fleckenstein 2007, entire; Miskelly
and Potter 2009, entire; Hanson et al. 2009, entire; Hanson et al.
2010, entire; Potter et al. 2011, entire; Vernon and Weaver 2012,
entire; Weaver and Vernon 2014, entire; Potter 2015a in litt.; Vernon
2015a, entire).
Abundance
In our 2006 12-month finding, we estimated the abundance of island
marble butterflies to be ``probably less than 500 butterflies, and
possibly as low as 300 individuals'' (71 FR 66292, November 14, 2006,
p. 66295). These numbers were based on limited data, and their accuracy
is uncertain. Since 2006, there have been several efforts to either
directly estimate population size or evaluate changes in relative
abundance through time (described below). In addition, captive-rearing
and release of butterflies was initiated in 2013, and as of the spring
of 2018, over 500 captive-raised butterflies have been released at
American Camp to supplement the population (SJINHP 2018, in litt.) (see
the discussions of conservation efforts under Factors A and C, below,
for more details).
Site Occupancy--The number of sites where the island marble
butterfly is detected each year is a useful indicator of coarse-scale
changes in abundance. The island marble butterfly has been recorded at
a total of 63 individual sites since rangewide surveys began in 2005:
The species was found at 37 sites in and around American Camp and 26
sites outside of American Camp (Miskelly and Potter 2005, pp. 7-14;
Miskelly and Fleckenstein 2007, pp. 14-19; Miskelly and Potter 2009,
pp. 7-8, 10-11; Hanson et al. 2009, pp. 10-11, 24-28; Hanson et al.
2010, pp. 12-13, 26-30; Potter et al. 2011, pp. 10-23, 15-23; Potter
2012, unpublished; Potter 2013, unpublished; Vernon and Weaver 2012,
pp. 4-7; Weaver and Vernon 2014, pp. 5-8). The number of occupied sites
recorded at American Camp is somewhat confounded by changes in survey
methods and effort through time (see ``Survey Effort,'' above). We
recognize this as a potential source of uncertainty, but note that both
transect data and anecdotal observations suggest a population decline
at American Camp since monitoring began in 2004 (see Transect Counts,
below).
The largest number of concurrently occupied sites reported was 25
in 2007, 10 of which were outside of American Camp (Miskelly and Potter
2009, pp. 7-8, 10-11; Potter et al. 2011, pp. 15-16). The number of
occupied sites declined every year from 2007 to 2011, with the species
detected at only seven sites in 2011, only one of which was outside of
American Camp. In 2015, adult island marble butterflies were detected
at only four of the regularly monitored sites at American Camp, the
fewest occupied sites ever recorded, and no adults, eggs, or larvae
were detected outside of the greater American Camp area (Potter 2015a
in litt.; NPS 2015, entire; Vernon 2015b, entire), although there were
two observations of single adult butterflies flying just beyond the
boundary of the park that were not recorded in formal surveys by NPS
(Potter 2015a, in litt.). Island marble butterflies were detected as
eggs in six additional research plots at American Camp (Lambert 2015d,
p. 4), but none of the eggs tracked in the research plots survived to
the fifth larval instar (Lambert 2015d, p. 13). In 2016 and 2017,
larval habitat for the island marble butterfly at American Camp
increased substantially, and survivorship of individuals tracked from
eggs through fifth instar larvae increased from zero in 2015 to 3
percent in 2016 (Lambert 2016a, pp. 10, 21), but decreased to 1 percent
in 2017, the last year for which survivorship data were collected
(Lambert 2017, pp. 3, 12).
The reasons for the precipitous decline in the number of occupied
sites since 2005 are not known with certainty, but the near-complete
loss of habitat outside of American Camp in some years is likely a
principal cause. Habitat loss has been caused by road maintenance,
mowing, cultivation of land, intentional removal of host plants,
improperly timed restoration activities, development, landscaping, deer
browse, and livestock grazing (Miskelly and Potter 2005, p. 6; Miskelly
and Fleckenstein 2007, p. 6; Miskelly and Potter 2009, p. 9; Hanson et
al. 2009, p. 18; Hanson et al. 2010, p. 21; Potter et al. 2011, p. 13).
Transect Counts--Counts along transects can provide a measure of
relative abundance, which can be useful in assessing changes in the
population among sites and through time (Peterson 2010, pp. 12-13).
From 2004 to 2008, Lambert (2009) counted adult island marble
butterflies along transects at American Camp (14 established in 2004,
and an additional 2 (for a total of 16) established in 2005), finding a
consistent and significant decline in the number of adults observed:
They counted 270 in 2004, 194 in 2005, 125 in 2006, 71 in 2007, and 63
in 2008 (Lambert 2009, p. 5). These raw counts were also translated to
relative encounter rates that account for differences in survey effort
across years, and these encounter rates also showed a marked decline
until 2016 (USFWS 2016). Four of these transects were monitored by NPS
almost continuously from 2004 to 2016 (one transect was not monitored
from 2009 to 2011), and relative encounter rates were calculated that
accounted for transect length and the number of times the transect was
surveyed each year. The relative encounter rate on these transects
declined substantially between 2004 and 2015, from almost 2 butterflies
per 100 meters surveyed in 2004, to approximately 0.3 butterflies per
100 meters in 2015 (USFWS 2016). Survey results for 2016 improved
across the three transects consistently monitored at American Camp,
with approximately 0.6 butterflies per 100 meters. While an observation
of 0.6 butterflies per 100 meters reflects an improvement from recent
years, this improvement does not reverse the overall decline observed
since monitoring began in 2004. The Service has not received updated
transect data for the flight seasons of 2017 or 2018.
Mark-Release-Recapture--Mark-release-recapture (MRR) studies were
conducted at American Camp in 2008 and 2009 (and at one additional site
on San Juan Island--the Pear Point Gravel Quarry, which is no longer
occupied) (Peterson 2009, 2010, entire). These studies sought to
address several demographic questions and to assess whether transect
counts were a reliable method to estimate changes in the population
through time (Peterson 2009, p. 3). MRR population estimates were
generated for three focal areas at American Camp in 2009: The western
end of American Camp (an estimated 50 individuals), American Camp below
the Redoubt (an estimated 39 individuals), and the dunes at American
Camp (an estimated 24 individuals). However,
[[Page 26790]]
because American Camp was not surveyed in its entirety, these areas
represent an unquantified fraction of the occupied habitat at American
Camp; therefore, we cannot extrapolate from this information to
estimate the rangewide population.
In summary, monitoring efforts have varied since 2008, but reports
from NPS indicate an ongoing decrease in the relative abundance of the
island marble butterfly at American Camp, suggesting that total numbers
continue to decline (Vernon and Weaver 2012, pp. 5-6; Weaver and Vernon
2014, p. 6). While reliable and precise rangewide population estimates
have not been produced for this species, the available evidence
suggests that the species has a very small population that has declined
substantially since monitoring began in 2004.
Habitat
The island marble butterfly has three known host plants, all in the
mustard family (Brassicaceae). One is native, Lepidium virginicum var.
menziesii (Menzies' pepperweed), and two are nonnative: Brassica rapa
(no agreed-upon common name, but sometimes called field mustard;
hereafter referred to as field mustard for the purposes of this
document) (ITIS 2015b, entire), and Sisymbrium altissimum L. (tumble
mustard) (Miskelly 2004, pp. 33, 38; Lambert 2011, p. 2).
All three larval host plants occur in open grass- and forb-
dominated vegetation systems, but each species is most robust in one of
three specific habitat types: Menzies' pepperweed at the edge of low-
lying coastal lagoon habitat; field mustard in upland prairie habitat,
disturbed fields, and disturbed soils, including soil piles from
construction; and tumble mustard in sand dune habitat (Miskelly 2004,
p. 33; Lambert 2011, pp. 24, 121-123). While each larval host plant can
occur in the other habitat types, female island marble butterflies tend
to select specific host plants in each of the three habitat types
referenced above, likely because certain host plants are more robust in
each habitat type during the flight season (Miskelly 2004, p. 33;
Lambert 2011, pp. 24, 41, 50, 54-57, 121-123; Shrum 2018, in litt.).
Host plants that establish and grow outside of their primary habitat
type typically are less robust, and female butterflies do not appear to
choose them preferentially but may use them when other larval habitat
is limited (Lambert 2011, pp. 24, 41, 50, 54-57, 121-123; Shrum 2018,
in litt.).
Adults primarily nectar (forage) on their larval host plants
(Potter 2015e, pers. comm.), but use a variety of other nectar plants
including:
Abronia latifolia (yellow sand verbena),
Achillea millefolium (yarrow),
Amsinckia menziesii (small-flowered fiddleneck),
Cakile edentula (American sea rocket),
Cerastium arvense (field chickweed),
Erodium cicutarium (common stork's bill),
Geranium molle (dovefoot geranium),
Hypochaeris radicata (hairy cat's ear),
Lomatium utriculatum (common lomatium),
Lupinus littoralis (seashore lupine),
Myosotis discolor (common forget-me-not),
Ranunculus californicus (California buttercup),
Rubus ursinus (trailing blackberry),
Taraxacum officinale (dandelion),
Toxicoscordion venenosum (death camas, formerly known as
Zigadenus venenosus), and
Triteleia grandiflora (Howell's brodiaea, formerly
Brodiaea howellii) (Miskelly 2004, p. 33; Pyle 2004, pp. 23-26, 33;
Miskelly and Potter 2005, p. 6; Lambert 2011, p. 120; Vernon and Weaver
2012, appendix 12; Lambert 2015a, p. 2, Lambert 2015b, in litt.). Of
these additional nectar resources, island marble butterflies are most
frequently observed feeding on yellow sand verbena, small-flowered
fiddleneck, and field chickweed (Potter 2015e, pers. comm.). Adults
primarily use low-statured, white flowering plants such as field
chickweed as mating sites (Lambert 2014b, p. 17).
Biology
The island marble butterfly life cycle comprises four distinct
developmental phases: Egg, larva, chrysalis, and butterfly. Development
from egg to chrysalis takes approximately 38 days and includes five
instars (phases of larval development between molts) (Lambert 2011, p.
7). Female island marble butterflies produce a single brood per year,
and prefer to lay their eggs individually on the unopened terminal
flower buds of their larval host plants (Lambert 2011, pp. 9, 48, 51).
Gravid female butterflies appear to select plants with many tightly
grouped flower buds over host plants with fewer buds, and they tend to
avoid laying eggs on inflorescences (flower heads) where other island
marble butterflies already have deposited eggs (Lambert 2011, p. 51).
However, the number of eggs laid on a single host plant has been
observed to vary with the density and distribution of host plants and
may also be affected by host plant robustness as well as the age of the
individual female butterfly (Parker and Courtney 1984, entire; Lambert
2011, pp. 9, 53, 54).
First instar larvae are able to feed only on tender portions of the
host plant, such as developing flower buds and new growth, and
initially move no more than a few centimeters from where they hatch
before they must feed; thus, larvae that hatch from eggs located more
than a few centimeters from a host plant's flower heads often starve
before reaching a suitable food source (Lambert 2011, pp. 12-13). The
limited locomotion of newly hatched larvae and their reliance on tender
flower buds as a food resource leads to a concentration of early-instar
larvae near the tips of their larval host plants (Lambert 2011, p. 13).
Larvae become more mobile in later instars, and their better developed
mouthparts allow them to consume older, tougher plant material.
Eventually, they may move to stems of other nearby host plants to
forage (Lambert 2011, pp. 15-17).
The fifth (last) instar larvae ``wander'' through standing
vegetation, never touching the ground, as they search for a suitable
site on which to pupate (form a chrysalis) (Lambert 2011, p. 20). The
greatest distance a fifth instar larva has been observed to move from
its final larval host plant was 4 meters, but few observations exist
(Lambert 2011, p. 19). Fifth instar larvae select slender dry stems in
the lower canopy of moderately dense vegetation as sites for pupation
and entering diapause, a state of suspended development (Lambert 2011,
p. 21).
Island marble butterflies spend the largest portion of their annual
life cycle in diapause as chrysalids. They enter diapause in midsummer
and emerge as butterflies in the spring of the following year. One
island marble chrysalis remained in diapause for 334 days (11 months)
(Lambert 2011, p. 22). Extremely low survivorship at early life-history
stages has been found in recent years (e.g., of 136 and 226 individual
eggs tracked in 2014 and 2015, respectively, zero survived to pupation;
Lambert 2015d, p. 13).
Adult island marble butterflies emerge from early April to mid-June
and live as winged adults for up to 16 days (Peterson 2009, p. 7;
Peterson 2018, in litt.; Vernon 2018, in litt.), with most persisting
for a much shorter period; estimates range from 2 to 9 days (Lambert
2011, pp. 50, 180; Peterson 2009, p. 7).
Males emerge 4 to 7 days before females and patrol hillsides in
search of
[[Page 26791]]
mates (Lambert 2011, p. 47). Male island marble butterflies have been
observed to prefer low-statured vegetation, generally avoiding flight
over expanses of tall grasses (Miskelly 2018, in litt.). Male island
marble butterflies are attracted to white (ultraviolet-reflecting)
objects that may resemble females and have been observed to investigate
white flowers (e.g., field chickweed and yarrow), white picket fences,
and white lines painted on the surface of roads (Lambert 2011, p. 47).
When a male locates a receptive female, mating may occur hundreds of
meters from the nearest larval host plant, increasing the potential
extent of adult habitat to include a varied array of plants and
vegetative structure (Lambert 2011, p. 48). Individual adult island
marble butterflies seldom disperse distances greater than 0.4 mi (0.6
km), with the greatest documented dispersal distance being 1.2 mi (1.9
km) (Peterson 2010, pp. 3, 12).
Island marble butterflies generally exhibit weak site fidelity and
low to intermediate dispersal capacity. When considered rangewide, the
island marble butterfly exists as a group of spatially separated
populations that interact when individual members move from one
occupied location to another (Miskelly and Potter 2009, p. 14; Lambert
2011, p. 147). For the island marble butterfly, a population is defined
as a group of occupied sites close enough for routine genetic exchange
between individuals. Thus, occupied areas separated by distances
greater than 3 mi (4.8 km) with no intervening suitable habitat and a
low likelihood of genetic exchange are considered to be separate
populations (Miskelly and Potter 2009, p. 12). Five potential
populations of island marble butterflies were identified and described
in detail in the 2006 12-month finding (71 FR 66292, November 14, 2006,
p. 66294): American Camp and vicinity, San Juan Valley, Northwest San
Juan Island, Central Lopez Island, and West Central Lopez Island. As
described previously, only the population at American Camp has been
detected since 2012.
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations in title 50 of the Code of Federal Regulations (50 CFR part
424) set forth the procedures for determining whether a species is an
endangered species or threatened species. The Act defines an endangered
species as ``in danger of extinction throughout all or a significant
portion of its range,'' and a threatened species as ``likely to become
an endangered species within the foreseeable future throughout all or a
significant portion of its range.'' Section 4(a)(1) requires the
Secretary to determine whether a species is an endangered species or
threatened species because of any of the following five factors: (A)
The present or threatened destruction, modification, or curtailment of
its habitat or range; (B) overutilization for commercial, recreational,
scientific, or educational purposes; (C) disease or predation; (D) the
inadequacy of existing regulatory mechanisms; or (E) other natural or
manmade factors affecting its continued existence.
To inform the determination, we complete a status assessment in
relation to the five factors using the best available scientific and
commercial data. The status assessment provides a thorough description
and analysis of the stressors, regulatory mechanisms, and conservation
efforts affecting individuals, populations, and the species. We use the
terms ``stressor'' and ``threat'' interchangeably, along with other
similar terms, to describe anything that may have a negative effect on
the island marble butterfly. In considering what factors might
constitute threats, we must look beyond the mere exposure of the
species to the factor to determine whether the species responds to the
factor in a way that causes actual impacts to the species. If there is
exposure to a factor, but no response, or only a positive response,
that factor is not a threat. The mere identification of threats that
could affect the island marble butterfly is not sufficient to compel a
finding that listing is appropriate. Rather, we evaluate the effects of
the threats in light of the exposure, timing, and scale of the threats,
both individually and cumulatively, and any existing regulatory
mechanisms or conservation efforts that may ameliorate or exacerbate
the threats in order to determine if the species meets the definition
of an endangered species or threatened species.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Since we first analyzed stressors to the island marble butterfly's
habitat on San Juan and Lopez Islands in 2006, the species'
distribution has contracted, and it is now known only from American
Camp and the immediate vicinity on San Juan (see ``Distribution,''
above). Island marble butterfly larval habitat in natural landscapes,
such as that found at American Camp, is patchy at best, making it
difficult to estimate the acreage of larval host plants. Additionally,
larval host plants are early successional species that thrive in
disturbed habitats. This can result in larval habitat patches that may
be present one year and gone the next, depending on the level of
disturbance present on the landscape.
Development
Residential development occurs on both San Juan and Lopez Islands,
primarily on private lands. Habitat loss from development affects the
island marble butterfly by reducing the availability of secure habitat
that will persist long enough for the island marble butterfly to
complete its life cycle. Development may also affect the known occupied
range of the island marble butterfly by constraining the amount of
stepping-stone habitat (patches of habitat too small to maintain an
established population, but large enough to allow for connectivity
between larger suitable patches) for dispersal. In addition, mowing or
removal of host plants (e.g., for landscaping around developments) may
also remove island marble butterfly habitat or prevent its
establishment. Because female island marble butterflies selectively lay
their eggs on the inflorescences (flowering head) of tall, robust
plants (Lambert 2011, p. 55), mowing host plants reduces the
availability of suitable oviposition (egg laying) sites for the island
marble butterfly.
Within American Camp, which is protected by NPS regulations (see
Factor D discussion, below), development is not a threat to the island
marble butterfly. However, residential development was a threat to
island marble butterfly habitat in the Cattle Point Estate and Eagle
Cove developments adjacent to American Camp. These areas accounted for
199 ac (81 ha) of island marble butterfly habitat, or 18 percent of
occupied habitat in 2006, which are now unoccupied due to habitat loss
(Potter 2015a, in litt.) associated with development (e.g., mowing,
landscaping, or removal of host plants) (Miskelly and Potter 2005, p.
6; Miskelly and Fleckenstein 2007, p. 6; Hanson et al. 2009, p. 9).
In 2006, we noted that development was occurring less rapidly in
the areas to the north and west of American Camp and on Lopez Island
where lands comprised small, rural farms with pastures and low-density
residential properties. We concluded that these areas, containing about
361 ac (146 ha), or 32 percent of the occupied habitat as of 2006,
would be managed in a way
[[Page 26792]]
that was compatible with island marble butterfly habitat. Since that
time, the amount of farmland in San Juan County has decreased, with the
greatest loss of farmland in San Juan County attributed to the
subdivision of larger farms into smaller parcels, which have then been
developed (San Juan County Agricultural Resources Committee 2011, p.
23). While there are no estimates of the amount of potential habitat
for the island marble butterfly lost specifically to development,
habitat loss outside of American Camp from a variety of sources has
been substantial (Miskelly and Potter 2005, p. 6; Miskelly and
Fleckenstein 2007, p. 6; Miskelly and Potter 2009, p. 9; Hanson et al.
2009, pp. 18-19; Potter et al. 2011, pp. 13-14; Potter 2015a, in
litt.). In addition to development of former agricultural lands,
perhaps more significant are the management practices on these lands
that effectively preclude recolonization by island marble butterflies
or create population sinks (habitat patches that attract dispersing
individuals, but do not allow them to complete their life cycle and
reproduce) (see ``Agricultural Practices,'' below). We conclude that
development has substantively contributed to the extirpation of the
island marble butterfly outside of American Camp and remains one of
several factors impeding successful recolonization of previously
occupied habitats; however, because American Camp is protected from
development by NPS regulations and is where the species solely occurs,
development is not a threat currently acting on the remaining extant
population of the species.
Road Construction
In our 2006 12-month finding (71 FR 66292; November 14, 2006), we
evaluated the impact of a planned road relocation project (Cattle Point
Road relocation project) through American Camp. Cattle Point Road is
the only point of access for residents at the southeastern tip of San
Juan Island and traverses the slope of Mount Finlayson, effectively
bisecting occupied island marble butterfly habitat at the park. We
estimated that the relocation would cause temporary loss of as much as
13 ac (5 ha) of island marble butterfly habitat due to clearing and
removal of larval host plants, although there was no known breeding
habitat along the highway at that time. We concluded that the road
realignment was likely to proceed with little mortality to the island
marble butterfly.
Since 2006, we have worked closely with NPS and the Federal Highway
Administration (FHA) to ensure that project impacts were avoided or
minimized. Once the project began, in 2015, the Service, NPS, and WDFW
actively surveyed the road alignment to remove host plants before they
could attract oviposition by female island marble butterflies and to
rescue island marble butterfly eggs and larva from any larval host
plants that might have been overlooked. Island marble butterfly larval
habitat in natural landscapes, such as that found at American Camp, is
patchy at best, making it difficult to estimate the acreage of larval
host plants. While the area affected by road construction was estimated
to be 13 ac (5 ha), larval host plants did not occur in dense patches
across the construction site. As a result of these efforts, far less
suitable habitat for island marble butterflies was temporarily lost
than we anticipated in 2006, and impacts to the island marble butterfly
population were significantly reduced and potentially completely
avoided.
Habitat restoration will continue for several years; once it is
completed, we anticipate that the project will be a net benefit to the
quantity and quality of island marble butterfly habitat in the project
area due to early coordination with the FHA and the proactive
conservation measures they implemented throughout the process. These
conservation measures included the proactive removal of all larval host
plants from the footprint of the project described above (so that
butterflies do not lay eggs on plants bound to be destroyed) and the
reseeding of larval and nectar host plant species in the disturbed
areas. These measures will both increase the quantity and improve the
quality of the habitat surrounding the finished project. In conclusion,
road construction is not currently a threat to the island marble
butterfly.
Road Maintenance
Road maintenance that destroys or negatively affects island marble
butterfly larval host plants has been a concern since 2005, when it was
documented as destroying occupied larval habitat on both San Juan and
Lopez Islands (Miskelly and Potter 2005, p. 6). For example, in 2005,
at Fisherman's Bay tombolo (a narrow beach landform that connects the
mainland to an island) on Lopez Island, road maintenance crews
deposited a quantity of sand on occupied larval host plants in an
effort to reduce the fire hazard of the vegetation in preparation for a
Fourth of July fireworks display. In addition to the deposition of sand
on occupied habitat, the remainder of the site was mowed by road
maintenance crews, removing all remaining larval host plants. There
were no detections of the island marble butterfly in 2006, a single
detection at the tombolo in 2007, and none through 2015 (Miskelly and
Potter 2009, p. 21; Potter et al. 2011, p. 16; Potter 2015a, in litt.).
Roadside maintenance has resulted in the destruction of suitable
habitat on Lopez Island and outside of American Camp on San Juan Island
(Miskelly and Potter 2005, p. 6). Despite changes in roadside
maintenance practices to address habitat loss, these protections were
not implemented uniformly throughout San Juan County, nor were they
implemented with the immediacy necessary to allow for widespread
persistence of island marble habitat along roadsides (Potter 2016,
pers. comm.). However, because roadside maintenance at American Camp
will be conducted in close coordination with the Service, we conclude
that whereas habitat loss associated with road maintenance activities
could be one of several factors impeding successful recolonization of
previously occupied habitats, it likely will have only minor impacts on
the island marble butterfly, given its current distribution. We do not
expect these impacts to change within American Camp in the future.
Vegetation Management
The island marble butterfly is present year round and largely
stationary while in its early developmental phases, becoming most
visible when it becomes a winged adult. The cryptic egg, larval, and
chrysalis forms make island marble butterflies vulnerable to land
management and restoration practices when those practices overlap
occupied areas. For example, in 2005, NPS conducted a prescribed fire
intended to restore native prairie, and this fire burned through the
occupied habitat during the butterfly's developmental stage and likely
killed all eggs and larvae within the affected area. Similarly, the use
of herbicides for the purpose of vegetation restoration in occupied
island marble butterfly habitat has been documented (Potter et al.
2011, p. 14). Although the direct effects of herbicides on island
marble butterflies have not been studied, indiscriminate application of
herbicides in areas occupied by eggs or larvae is likely to result in
mortality through elimination of larval host plants and primary food
resources.
Since 2010, the Service, NPS, WDFW, and other partners have
cooperated closely to achieve vegetation management and restoration
goals while also conserving the island marble butterfly and its
habitat, including nonnative larval host plants. As a result,
[[Page 26793]]
vegetation management has not resulted in significant harm to island
marble butterflies since 2010. The island marble butterfly is
vulnerable to vegetation management or restoration practices that are
improperly timed or poorly sited. However, this vulnerability does not,
by itself, result in impacts to the species. Currently, vegetation
management does not have a significant impact on the species because
the ongoing collaboration between cooperating partners has adequately
minimized the impacts of vegetation management actions at American
Camp.
Agricultural Practices
Agricultural activities that include tilling of the soil have been
identified as a stressor for the island marble butterfly (Potter et al.
2011, p. 14). Removal or destruction of habitat by conversion from an
agricultural condition that provides suitable habitat (e.g., old field
pasture) for island marble butterfly to an agricultural condition that
does not allow the island marble butterfly to complete its life cycle
(e.g., active cropping) has likely led to the decline of occupied
island marble butterfly habitat outside of American Camp and continues
to contribute to the curtailment of the former range of the species.
The species has not been detected since 2012 at any previously occupied
agricultural sites that have been surveyed (Potter et al. 2011, pp. 15-
16; Potter 2012, unpublished data; Potter 2013, unpublished data;
Vernon 2015b in litt., entire). In addition, no new occupied sites in
agricultural areas have been detected during surveys conducted in 2015
(Vernon 2015a, entire).
Practices on San Juan and Lopez Islands that require tilling the
soil, such as grain farming, can promote growth of field mustard (a
host plant) during the island marble butterfly's flight period if
tilling takes place during fall and winter months (e.g., December
through February), allowing field mustard seeds in the seed bank to
germinate and mature in synchrony with the needs of the island marble
butterfly. Because cereal crops compete with field mustard, the array
of established plants can result in a diffuse number of larval host
plants at a density attractive to female island marble butterflies
searching for an oviposition site. When actively cropped agricultural
areas with larval host plants occur near occupied habitat, they can
create an ``ecological trap'' if dispersing females lay eggs where the
larvae do not have adequate time to complete their life cycle before
the crop is harvested and the site is tilled for replanting the
following spring (Hanson et al. 2009, pp. 18-19; Miskelly and Potter
2009, p. 14).
Similarly, grazing can produce an ecological trap if females lay
eggs in suitable habitat that is then consumed by livestock (see
Herbivory by livestock, below). However, since the 1980s, farming on
San Juan Island has trended toward small market gardens, and large,
livestock-based farms have been reduced in number (San Juan County
Agricultural Resources Committee 2011, p. 16). Livestock grazing does
not currently overlap any areas known to be occupied by the island
marble butterfly; thus, livestock grazing is not currently a threat to
the island marble butterfly, although it could become a threat in the
future if the island marble butterfly were to become reestablished in
areas where grazing takes place. The best available scientific and
commercial information does not indicate that agricultural practices
currently affect the island marble butterfly because the known
population occurs on NPS lands that are not managed for agricultural
use.
Plant Succession and Competition With Invasive Species
All of the known larval host plants for the island marble butterfly
are annual mustard species that are dependent on open, early-
successional conditions for germination (Lambert 2011, p. 149).
Disturbance or active management maintains these conditions; otherwise,
plant succession and invasion by weedy native and nonnative plants
greatly inhibit germination and growth of larval host plants. These
processes of vegetation change thus degrade and reduce the availability
of habitat required by the island marble butterfly to complete its life
cycle.
Succession of open, low-statured vegetation to woody plants is a
natural process in the absence of anthropogenic burning or other forms
of disturbance. The cessation of Native American burning in the mid-
1800s resulted in the loss of prairie habitat in western Washington,
including the San Juan archipelago, due to tree and shrub encroachment
(Hamman et al. 2011, p. 317). Prairies were repeatedly burned during
historical times by Native Americans for a variety of reasons, and
areas used for cultivation of food plants, such as Camassia leichtlinii
or C. quamash (great camas and common camas, respectively), may have
been burned on an annual basis (Beckwith 2004, pp. 54-55; Boyd 1999,
entire; Chappell and Kagan 2001, p. 42).
Early estimates of the size of the prairie at American Camp suggest
it may have been as large as 1,500 acres (ac) (607 hectares (ha)) when
the first Europeans arrived (Douglas 1853, entire). Today, the prairie
is estimated to be 695 ac (281 ha) due, in part, to succession and
encroachment of Douglas-fir trees (Pseudotsuga menziesii) and other
woody vegetation (Rochefort et al. 2012, p. 9). Reclaiming and
maintaining open prairie habitat at American Camp requires active
management to control Douglas fir trees and other woody species
(Rochefort et al. 2012, p. 4).
Two of the three known larval hosts for the island marble butterfly
are introduced species that self-propagate into open, disturbed areas:
Field mustard and tumble mustard. In the absence of active restoration
or disturbance, other weedy plant species, as well as woody plants and
trees, are likely to colonize the site, eventually outcompeting the
early-successional host plants. At American Camp, where remnant prairie
habitat persists, weedy species such as Elymus repens (quack grass),
Holcus lanatus (velvet grass), Cirsium arvense (Canada thistle), and
Vicia sativa (common vetch), among others, outcompete the larval host
plants in the absence of disturbance.
Competition with nonnative species also affects host plants in sand
dune habitat. The sand dunes represent a unique habitat type for the
island marble butterfly that includes open, shifting sands easily
colonized by the larval host plant, tumble mustard (Lambert 2011, p.
42). While Menzies' pepperweed and field mustard also occasionally
occur in dune habitat, tumble mustard is the host plant that occurs
there most commonly, is most robust in this habitat type, and can
create continuous stands of larval host plants under optimal conditions
(Lambert 2011, pp. 42, 65). When nonnative species such as Canada
thistle, hairy cat's ear, and Rumex acetosella (sheep sorrel) colonize
the sandy dune habitat, the dunes become increasingly stable and the
effect is a reduction in the available germination sites for tumble
mustard (Weaver and Vernon 2014, pp. 5, 9). Canada thistle has the
greatest potential to negatively affect dune habitat where it is
stabilizing the sand and facilitating establishment of grasses, which,
in turn, displace tumble mustard (Rochefort 2010, p. 28; Weaver and
Vernon 2014, p. 9).
Conditions for larval host plants continue to be degraded through
plant succession and invasion throughout the range of the island marble
butterfly. Loss of habitat conditions favorable for larval host plants,
and thus habitat loss for the island marble butterfly, occurs in
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at least two of three habitat types at American Camp, the only area
where the island marble butterfly is currently known to persist (Weaver
and Vernon 2014, pp. 5, 9). Loss of potentially suitable but not
currently occupied habitat resulting from succession also occurs in any
areas outside of American Camp where these processes take place. Due to
the extremely limited numbers and range of the island marble butterfly,
any further loss of habitat may lead to further decline of the species
and preclude its establishment in new areas.
Herbivory
Herbivory by deer: Black-tailed deer (Odocoileus hemionus
columbianus) are common in the San Juan Island archipelago. At the
single occupied site where island marble butterfly is currently known
to exist, black-tailed deer numbers appear to be increasing (Lambert
2014a, p. 3). Browsing deer prefer flowering plants when available, and
tend to select stems on the tops or sides of plants over the stems that
emerge lower on the stalk (Anderson 1994; p. 107; Lambert 2015c, in
litt., Thomas 2015, pers. obs.). Specifically, at study sites where
island marble butterflies exist, deer browse selectively on robust
larval host plants with several inflorescences of compact flower buds--
the same plant characteristics preferred by female island marble
butterflies as egg-laying sites (Lambert 2011, p. 103). The effect of
deer browsing on larval host plants is three-fold. First, it destroys
suitable egg-laying habitat; second, it stimulates rapid growth of
lateral (side) stems on the plant, rendering the plant less likely to
support an individual butterfly from egg to late-instar larva; and
third, continual browsing of the flowering portion of the plant reduces
seed production, resulting in fewer larval host plants over time
(Lambert 2011, p. 10; Lambert 2014a, p. 10; Lambert 2015d, p. 17). Deer
browsing, which stimulates rapid lateral stem growth, results in
increased mortality when eggs are laid on the flowers of lateral stems
on the larval host plants (Lambert 2011, p. 10). Immobile, early-instar
larvae of island marble butterfly present on these stems are left
behind as the stems grow away from them. When the larvae can no longer
access the tender tissues at the developing tips of the plant that they
require for survival, they die from starvation (Lambert 2011, p. 10,
Lambert 2015e, in litt.).
The destructive effects of deer browsing on larval habitat are
common where surveys have taken place throughout the known range of the
island marble butterfly (Miskelly and Fleckenstein 2007, p. 6; Miskelly
and Potter 2009, pp. 11, 15; Hanson et al. 2009, pp. 4, 13, 19-20;
Hanson et al. 2010, pp. 21-22; Potter et al. 2011, pp. 5, 13; Lambert
2011, p. 104; Lambert 2014a, entire; Weaver and Vernon 2014, p. 10;
Vernon and Weaver 2012, p. 9; Lambert 2015d, pp. 17-18). At American
Camp, herbivory by deer has affected 95 percent of field mustard plants
in some years (Lambert 2011, p. 127). Deer exclusion fencing has been
erected to protect suitable habitat at American Camp to counteract the
impacts of deer browsing, but the fencing has not been fully effective
at excluding deer, and deer have continued to consume occupied larval
host plants (see ``Habitat Conservation and Restoration,'' below).
Habitat loss attributable to herbivory by deer is ongoing and
extensive throughout the current and former range of the island marble
butterfly, and may be increasing, with substantial impacts to the
species (Lambert 2011, pp. 85-104; Lambert 2014a, p. 3; Lambert 2015d,
pp. 14-18). The effect of habitat loss due to deer herbivory is
compounded by the effect of inadvertent predation when the larval host
plants are occupied by eggs or larvae (see ``Incidental Predation''
under the Factor C discussion, below).
Herbivory by livestock: Livestock readily consume field mustard,
which is often cultivated in pastures as a way to improve forage for
cows and sheep (Smart et al. 2004, p. 1; McCartney et al. 2009, p.
436). There is no livestock grazing at American Camp, but livestock
pastures are present on San Juan and Lopez Islands in areas that may
contain suitable habitat for dispersing island marble butterflies. When
cattle or sheep are present on lands where field mustard is grown, they
readily consume the flower heads, stems, and stalk of the plant,
destroying suitable island marble butterfly habitat (Miskelly and
Potter 2009, p. 15; Hanson et al. 2009, p. 20; Hanson et al. 2010, p.
21). Like conversion of old field pastures to active cropping,
cultivation of field mustard as a forage species for livestock
potentially creates an ecological trap for the island marble butterfly
when cultivation takes place within dispersal distance of an occupied
site, and female island marble butterflies lay eggs in a patch of field
mustard that is later consumed or trampled by livestock before any
larvae can complete their life cycle (see ``Incidental Predation''
under Factor C, below, for further discussion). In conclusion, loss of
potential habitat to livestock grazing can prevent reestablishment and
persistence of suitable habitat for the species outside of American
Camp. However, because livestock grazing is not allowed on American
Camp where the species occurs, herbivory by livestock is not a threat
currently acting on the remaining population of the species.
Herbivory by rabbits: The European rabbit, Oryctolagus cuniculus,
is a common invasive species in the San Juan Islands (Hall 1977,
entire; Burke Museum 2015). At American Camp, European rabbits have
been established for more than a century, following their introduction
to San Juan Island during the late 1800s (Couch 1929, p. 336). Grazing
by European rabbits, when they proliferate, affects both vegetative
structure and composition, reducing both the number and kind of plant
species near their warrens (network of burrows) (Eldridge and Myers
2001, pp. 329, 335). Herbivory by European rabbits negatively affects
the recruitment and establishment of larval host plants; where rabbits
occur at American Camp, few larval host plants for the island marble
butterfly persist due to the intense grazing pressure (Radmer 2015, in
litt.). When larval host plants do germinate near European rabbit
warrens, they are consumed before the plants are large enough for
female island marble butterflies to recognize and use them.
Population monitoring of European rabbits has been conducted at
American Camp from 1985 to 2015, documenting an estimated population
high of approximately 1,750 rabbits in 2006, and a low of fewer than
100 in 2012. From 2009 through 2012, the population was estimated to be
100 animals or fewer, and the condition of vegetation in the affected
area had ``changed dramatically'' with the reduction in rabbit grazing
pressure (West 2013, pp. 2, 4). The most recent population estimate, in
2015, was approximately 500 animals, indicating that the rabbit
population at American Camp is currently on the rise (West 2015, in
litt.). If European rabbits remain uncontrolled at American Camp, their
population is likely to fluctuate but continue expanding overall in the
next decade, similar to the patterns documented in the past 30 years of
monitoring data. The majority of the European rabbit population has
been, and may continue to be, centered on a single large field near the
middle of American Camp, surrounded by areas that include island marble
butterfly habitat. As their population grows, we expect the impacts of
European rabbits to expand, encroaching upon and destroying additional
island marble butterfly habitat.
[[Page 26795]]
Herbivory by brown garden snails: The nonnative brown garden snail
(Cornu aspersum, formerly Helix aspersa) is a generalist herbivore that
has been reported to occur in great numbers in some areas where island
marble butterfly previously occurred (e.g., Pear Point Gravel Pit or
`La Farge' and San Juan Valley), where it feeds on field mustard and
tumble mustard, the two most common larval host plants for the island
marble butterfly (Hanson et al. 2010, p. 18; Potter et al. 2011, p.
13). State biologists removed hundreds of snails that were feeding on
larval host plants at Pear Point in 2010, when the island marble
butterfly still occupied this site (Potter et al. 2011, p. 13). The
brown garden snail has extremely high reproductive potential; it
matures within 2 years and can produce more than 100 eggs five or six
times each year (Vernon 2015c, p. 1). The number of brown garden snails
observed on San Juan Island has increased substantially between the
years of 2009 and 2015 (Potter et al. 2011, p. 13; Vernon 2015c in
litt., entire).
In 2015, the brown garden snail was observed in San Juan Valley, a
site formerly occupied by the island marble butterfly, and in 2016, the
brown garden snail was documented in the South Beach area at American
Camp by a Service biologist (Vernon 2015c in litt., entire; Vernon
2015a p. 4; Reagan 2016, pers. obs.). High numbers of brown garden
snails have been documented in highly disturbed sites previously
occupied by island marble butterfly, and since our 2016 12-month
finding (81 FR 19527; April 5, 2016) was published, they have been
found invading the natural areas in American Camp currently occupied by
the island marble butterfly and its host plants (Shrum 2017, in litt.).
This most recent development indicates that brown garden snail is now
well established within American Camp and the habitat currently used by
the island marble butterfly, raising the likelihood that herbivory by
the brown garden snail will result in habitat loss or degradation to an
extent that can affect the butterfly's survival and reproductive
success. While there are no documented accounts of snails directly
consuming island marble butterfly eggs or larvae, the brown garden
snail poses a threat to the island marble butterfly by consuming larval
host plants, whether those plants are occupied or not. Therefore,
herbivory by brown garden snails is detrimental to the butterfly's
overall survival and reproductive success because it can both reduce
the quantity of suitable host plants available and cause incidental
mortality of individuals.
Storm Surges
The nearshore lagoon habitat for island marble butterfly is close
to sea level. Three intermittently occupied sites are in lagoons along
the northeastern edge of American Camp, where they are partially
protected from tidal surges that arrive from the west. One of these
lagoons had the highest relative encounter rate of all monitored
transects at American Camp in 2015, and raw counts at this site
represented roughly 50 percent of the adult island marble butterflies
recorded during annual monitoring for that year. Storm surges,
attributable to the combined forces of high tides and high-wind storm
events, inundate these low-lying lagoon areas intermittently, as
evidenced by the deposition of driftwood logs along the shoreline.
These events have occurred with some regularity through time, but the
most recent episodes of inundation have been particularly destructive
of nearshore island marble butterfly habitat. A storm surge event in
the winter of 2006 resulted in the deposition of gravel substrate and
driftwood over an island marble butterfly research plot where the one
native larval host plant, Menzies' pepperweed, had been established,
reducing the number of plants by more than 50 percent (Lambert 2011,
pp. 145-146). This same storm surge likely destroyed any butterflies
that were overwintering in nearshore habitat as chrysalids and had a
local population-level impact; low numbers of individual island marble
butterflies, eggs, and larvae were detected at the site for several
years following the event (Lambert 2011, p. 99; Lambert 2015f, in
litt.).
The frequency of storm surges large enough to inundate the lagoons
and destroy island marble butterfly habitat has previously been
relatively low, but since 2006, at least one storm surge event (in
2009) was strong enough to inundate the low-lying habitat (Whitman and
MacLennan 2015, in litt.). The frequency of these events is expected to
increase with sea-level rise associated with climate change (see Factor
E discussion, below). In turn, we anticipate a concomitant increase in
the potential for destruction of low-lying habitat for the island
marble butterfly--approximately 15 to 20 percent of the species'
habitat in American Camp (Lambert 2011, p. 145; Adeslman et al. 2012,
pp. 79-86; Whitman and MacLennan 2015, in litt.; NOAA 2015a, entire;
NOAA 2015b, entire).
The Menzies' pepperweed (the native host plant) occurs almost
exclusively in the low-lying nearshore habitat, and female island
marble butterflies have been observed to deposit eggs on only a single
species of larval host plant at any one site. (Despite close
observations of ovipositing females, researchers have not observed
females depositing eggs on more than one type of larval host plant at
any one site.) Therefore, if this habitat type is lost, an unknown
proportion of diversity--in habitat use or adaptive potential--in the
island marble butterfly could be lost as well. Furthermore, low-lying
habitat comprises an estimated 15 to 20 percent of habitat for the
species at American Camp, a considerable proportion of the restricted
range of the species. Due to the small size of the remaining known
population of the island marble butterfly and the importance of this
low-lying habitat demonstrated by high encounter rates during surveys,
loss or degradation of this habitat will likely lead to a further
decline of the species.
Habitat Conservation and Restoration
San Juan Island National Historical Park has been implementing
conservation measures for the island marble butterfly since shortly
after its rediscovery in 1998. From 2003 through 2006, NPS created
experimental prairie disturbances and vegetation plots to better
understand how to manage the prairie and create island marble butterfly
habitat. This work resulted in recommendations for the best method of
reducing the cover of invasive grasses by using prescribed fire
followed by herbicide treatment (Lambert 2006, p. 110). However, the
work was not reproduced at larger scales, nor was it continued in ways
sufficient to maintain adequate habitat on the landscape over time.
In 2018, we renewed a conservation agreement with NPS for the
island marble butterfly that contained several conservation actions
that will be applied to manage habitat for the species into the future.
The renewed agreement, which was signed in December 2018, committed NPS
to: (1) Restore, where needed, habitat for island marble butterfly, as
jointly agreed; and (2) avoid impacts to island marble butterflies,
eggs, larvae, and host plants during the implementation of all NPS
management actions by working in habitat that was not occupied by
island marble butterflies. All vegetation treatment will be conducted
in the fall after the island marble butterfly has entered diapause. We
expect the history of collaborative conservation of the island marble
butterfly by NPS and the
[[Page 26796]]
Service to continue for the foreseeable future.
From 2007 through 2011, NPS managed encroaching plant species using
multiple methods to open up areas where larval host plants could
naturally germinate from the seed bank (NPS 2013, pp. 7-11). NPS also
planted more than 100,000 native grass plugs in mechanically treated
areas (NPS 2013, p. 7), which improved the native composition of the
prairie grassland features but did not result in increased cover of the
larval host plants needed to support the island marble butterfly. The
Service continued to work collaboratively with NPS to develop annual
work plans each year from 2013 through 2016; these work plans are
addenda to the 2006 conservation agreement for the island marble
butterfly. The goals and actions identified in the work plans have
changed, sometimes annually, in response to new information, adaptive
management needs, available funding, and other concerns. The 2013-2016
work plans identified and enacted several conservation actions to
address threats related to the destruction, modification, and
curtailment of island marble butterfly habitat at American Camp.
Prescribed fire, deer fencing of essential habitat, management of
invasive species, and experimental habitat restoration were all
implemented per annual work plans during this period.
These work plans initially included the use of prescribed fire in
small blocks (up to one acre) to disturb grassland habitat in an effort
to encourage larval host plant patches to establish from the seed bank.
These prescribed fire events resulted in very low germination of the
larval host plants, leading NPS to conclude that few larval host plant
seeds persist in the seed bank. In response, later annual work plans
recommended seeding the larval host plant species after a prescribed
burn. The 2016 annual work plan also included recommendations for the
development of novel methods for creating island marble butterfly
habitat.
In 2013, the Service funded the installation of deer exclusion
fencing at American Camp in an effort to reduce deer herbivory on
larval host plants (and the incidental consumption of eggs and larvae;
see discussion under Factor E, below) and to increase suitable
oviposition sites. Deer fencing was included in each year's annual work
plan since 2013, and continues to be employed as an exclusion
technique. Approximately 23 acres have been fenced since deer exclusion
efforts began in 2013 (Shrum 2015a, in litt.).
The various forms of deer exclusion fencing that have been used
have resulted in mixed success in preventing deer from consuming larval
host plants. For example, in 2015, electrified fencing alone proved
ineffective at excluding deer at three of five research sites at
American Camp (Lambert 2015d, p. 17). However, electric and wire-mesh
fencing combined have reduced deer herbivory on larval host plants when
compared to years when exclusion fencing was not employed (Lambert
2015d, p. 17). In one large expanse of habitat at American Camp, the
distribution of field mustard was essentially limited to the fenced
areas in 2015, although environmental conditions shifted substantively
in 2016, allowing for a large flush of persistent field mustard beyond
the fenced areas (Lambert 2014a, p. 23; Lambert 2015a, p. 5; Lambert
2015d, p. 17; Lambert 2016a, p. 35). Despite these challenges, deer
exclusion fencing remains an important tool for protecting island
marble butterfly habitat, especially early in the flight season when we
expect survivorship to be the highest (Lambert 2015d, p. 19). For
example, in 2016 (after the publication of our 12-month finding on
April 5, 2016 (81 FR 19527)), deer were completely excluded from
research sites at American Camp for the first time, resulting in one-
quarter acre of restored habitat for host plants, and increased
survival in island marble butterflies on field mustard than in previous
years (Lambert 2016a, p. 11).
The annual work plans have also included efforts to control weedy
native and nonnative species and encroaching woody plants.
Specifically, NPS has removed hundreds of Douglas fir trees and dozens
of acres of Rubus armeniacus (Himalayan blackberry), R. laciniatus
(blackberry), Symphoricarpos albus (snowberry), and Crataegus monogyna
(one-seeded hawthorn) from the American Camp prairie. These actions
have slowed the invasion of native and nonnative species and
encroachment by woody plants and have created early-successional
conditions that likely provided some nectaring habitat for the island
marble butterfly. However, few larval host plants germinated from the
seed bank in the areas cleared of encroaching plants. Another area of
focus under the work plan for controlling invasive species is herbicide
treatment of Canada thistle in the dunes.
NPS, in collaboration with the Service and other partners, has
supported experimental research into the active establishment of island
marble butterfly habitat since 2003. In 2014, an experimental approach
for establishing oviposition and larval habitat was proposed. The
Service, in coordination with NPS, WDFW, and two local island
conservation organizations (San Juan Preservation Trust (SJPT) and San
Juan County Land Bank (SJCLB)), developed a plan to determine whether
habitat patches for the island marble butterfly could be developed in a
way that could be scaled up efficiently in a landscape context (Lambert
2014b, entire). Thirty habitat patches were created on park property at
American Camp between 2014 and 2016, and 10 more will be created in
2017 (Lambert 2016a, p. 59). Early results from this work indicate that
habitat can be created quickly and that island marble butterflies
readily use these patches for egg laying and larval development if
larval host plants germinate in time to provide oviposition sites for
early-flying butterflies (Lambert 2015d, pp. 9-12).
Each year since 2013, NPS has collected and reared a small number
of eggs and larvae in a captive-rearing program (see discussion under
Factor C, below, for more information). In 2015, the captive
individuals emerged from diapause much later than the wild population.
Despite the use of the experimental plots for oviposition by these
late-flying, captive-reared females, none of the eggs and larvae
tracked in the experimental plots survived. The high mortality was
attributed to increased predation pressure by late-season spiders and
wasps (Lambert 2015d, p. 14) (see ``Direct Predation'' under Factor C,
below). Results of captive-rearing were better in 2016, when captive-
reared island marble butterflies emerged in synchrony with the wild
population. Survivorship from egg to fifth instar larvae was also
higher in the experimental plots in 2016; three percent of the tracked
larvae survived to the fifth instar, which is a relatively high
survival rate for the island marble butterfly.
The Service, in coordination with NPS, supports habitat
conservation efforts by funding local conservation groups to establish
habitat patches on three conserved sites across the former range of the
island marble butterfly. Two of these experimental habitat patches were
established outside of American Camp in 2015 and one in 2016. Each
experimental patch has been fully fenced to exclude herbivores
(primarily deer) and allow the larval host plants to grow without
herbivory pressure (also see Factor C, ``Incidental Predation,''
below).
[[Page 26797]]
Education and Outreach
In 2009, the Service provided funding to WDFW for the creation of a
species fact sheet and informational handout for the public about the
biology and conservation needs of the island marble butterfly. This
pamphlet provided outreach to interested parties and increased the
awareness of the public about the decline of the island marble
butterfly. The pamphlet provided basic information about how to protect
and support habitat essential to the island marble butterfly. In 2011,
the Service collaborated with NPS, WDFW, researchers from the
University of Washington, and the Center for Natural Lands Management
to reach out to the community in a local Island Prairie Educational
Symposium to present information on current approaches to prairie
management. Information gained through years of prairie conservation
efforts in other northern and southern Puget Sound prairie landscapes
was shared with the local island community. Information about the
island marble butterfly and the educational materials developed were
well distributed within the community; however, this effort did not
lead to the protection or restoration of habitat adequate to ameliorate
the threat of habitat loss for the island marble butterfly. Despite
considerable advances in habitat restoration, new habitat
establishment, captive rearing, herbivore exclusion, and outreach and
education, the number of individual island marble butterflies remains
small in the single remaining population.
Summary of Factor A
Habitat supporting the remaining population at American Camp is
protected from development and agriculture, but is exposed to the
threats of plant succession and invasive plant species; herbivory by
deer, rabbits, and brown garden snails; and storm surges. Habitat loss
is likely a major factor impeding the recolonization of areas outside
of American Camp. Outside of American Camp, removal of larval host
plants by mowing; roadside maintenance; road, residential, or urban
development; certain agricultural practices (such as tilling, cropping,
and grazing); and landscaping activities has substantially reduced the
amount of habitat available for recolonization by the island marble
butterfly either temporarily (e.g., mowing, tilling, cropping, or
grazing) or permanently (e.g., road, residential, and urban
development) since the island marble butterfly was rediscovered
(Miskelly and Fleckenstein 2007, p. 6; Miskelly and Potter 2009, p. 9;
Hanson et al. 2009, p. 18; Vernon 2015b in litt., p. 5). This habitat
removal is a primary factor in the loss of all the remaining
populations of this species outside of American Camp since 2006.
Since 2011, NPS has made substantial and sustained efforts to
expand island marble butterfly habitat and to improve the composition
and structure of the plant community to become more suitable for the
island marble butterfly. Due to challenges in establishing suitable
habitat and protecting it from the threats described above, only a few
acres of high-quality habitat for island marble butterfly have been
restored on the American Camp landscape. Many more acres within
American Camp have been improved by restoration actions or protected
from deer herbivory, but are not yet considered high quality or fully
secure from herbivory by deer. To date, these efforts may have resulted
in a small positive response in the island marble butterfly population,
as evidenced by the 3 percent increase in survivorship from the fourth
to fifth instar in 2016. However, the number of those individuals that
will successfully pupate and emerge as winged adults in the spring
remains to be seen. Conservation efforts by NPS have also resulted in
significant contributions to our understanding of island marble
butterfly habitat and threats to that habitat. Outside of American
Camp, the only conservation efforts that specifically create habitat
for the species are the small island marble butterfly habitat plots
established by SJPT and SJCLB. These efforts will be crucial to
establishing new populations of island marble butterfly in the future,
but the achievement is too recent for their effectiveness to be
evaluated, especially in the context of the extensive, ongoing habitat
loss from changing land use, changing agricultural practices, and other
factors that inhibit recolonization by island marble butterflies
outside of American Camp.
Despite successful habitat restoration experiments, continued use
of deer exclusion fencing, and the removal of woody plants and
nonnative and native weedy species, the increase in the total area of
currently suitable habitat within American Camp has not been fully
quantified, although it remains small (on the scale of quarters of
acres). Despite these minor gains in habitat as a result of restoration
since we published our 12-month finding on April 5, 2016 (81 FR 19527),
the range of the species--the number of sites within American Camp
where it is observed--has continued to contract, and the number of
island marble butterflies observed each year remains low. Conservation
measures will need to continue into the future, with monitoring to
assess their long-term value to the island marble butterfly. Until
measureable changes to the island marble butterfly population have been
documented, it will be difficult to determine whether the implemented
measures are effecting positive change in the status of the island
marble butterfly. Based on the analysis above, we conclude that plant
succession and competition with invasive species, herbivory by deer and
brown garden snails, and storm surges are likely to have population-
level impacts on the island marble butterfly.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Overutilization for Commercial or Recreational Purposes
Under NPS regulations, collection of living or dead wildlife, fish,
or plants, or products thereof, is prohibited on lands under the
jurisdiction of NPS without a permit (36 CFR 2.1(a)(1)(i) and
(a)(1)(ii)), but there are no State or County regulations that prohibit
recreational collection of the island marble butterfly at this time.
Rare butterflies and moths are highly prized by collectors, and an
international trade exists in specimens for both live and decorative
markets, as well as the specialist trade that supplies researchers
(Collins and Morris 1985, pp. 155-179; Morris et al. 1991, pp. 332-334;
Rieunier and Associates 2013, entire). Before the island marble
butterfly was formally described, collectors may have exerted little
pressure on the taxon because it was unknown and because it occurs in
remote islands that had been little-surveyed for butterflies. Following
formal description of the species in 2001, at least three inquiries
about potential for collection were made to WDFW, which is responsible
for managing fish and wildlife in the State of Washington, and one with
NPS at American Camp, which requires a permit for the collection of any
plant or animal from park property (Reagan 2015, in litt.). WDFW has
discouraged collection, and NPS rejected the single permit request for
collection it received (Reagan 2015, in litt.; Weaver 2015a, in litt.).
In addition to these permit requests, we are aware of one specimen of
the island marble butterfly purportedly being listed for sale on a
website devoted to trade in butterfly species (Nagano 2015, pers.
obs.), although the origin and authenticity of this specimen could not
be verified.
[[Page 26798]]
Even limited collection of butterfly species with small populations
could have deleterious effects on the reproductive success and genetic
variability within those populations and could thus contribute
eventually to extinction or local extirpation (Singer and Wedlake 1981,
entire; Gall 1984, entire). Capture and removal of females dispersing
from a population also can reduce the probability that new populations
will be established or that metapopulation structure will be developed
or maintained. (A metapopulation is a group of spatially separated
populations that interact when individual members move from one
population to another.) Collectors pose a potential threat because they
may not be aware of other collection activities, and are unlikely to
know, and may not care, whether or not they are depleting numbers below
the threshold necessary for long-term persistence of populations and
the species (Martinez 1999, in litt.). This is especially true if
collectors lack adequate biological training or if they visit a
collection area for only a short period of time (Collins and Morris
1985, p. 165). In addition, collectors often target adult individuals
in perfect condition, including females that have not yet mated or had
the opportunity to lay all of their eggs. Some collectors go to the
length of collecting butterfly eggs in order to rear perfect specimens
(USDOJ 1995, p. 2).
Collection of the island marble butterfly, which is prohibited on
NPS lands, could potentially occur without detection because occupied
areas are not continuously patrolled and adult butterflies do move
outside of protected areas onto adjoining lands where collection is not
currently prohibited. Consequently, the potential for collection of
adult island marble butterflies, and especially surreptitious
collection of early stages (eggs, larvae, and pupae) exists, and such
collection could go undetected, despite the protection provided on NPS
lands. Taking into consideration the small remaining population,
illegal collection could have strong detrimental effects on the known
population, were it to occur. However, no illegal collection efforts
for this species have been documented to date.
Scientific Overutilization
The widespread surveys that took place in the period 2005-2012
included capturing and releasing butterflies when necessary for
positive identification, as specified in Miskelly and Fleckenstein 2007
(p. 4). Although a limited number of individuals may have been injured
or killed during handling, no data exist on the number of individuals
captured, injured, or killed. To our knowledge, there have been three
documented instances of island marble butterfly collection or handling
for scientific purposes since the rediscovery of the species. In 2005,
two male specimens were collected by WDFW surveyors as vouchers to
document newly discovered island marble sites (Miskelly and Potter
2005, pp. 4, 5; Potter 2016, in litt.). In 2008, a mark-release-
recapture (MRR) study of the species' demography involved the capture
and marking of 97 individual adult island marble butterflies and
recapture of 56 butterflies across four separate sites, and some
individuals were recaptured more than once (Peterson 2009, entire;
Peterson 2010, entire). A single individual butterfly was collected as
a voucher specimen under a WDFW scientific collection permit in 2008
for the MRR study (Potter 2016, in litt.). The other scientific use of
the island marble butterfly of which the Service is aware took place in
2013, when two adult butterflies were collected by WDFW for a genetic
assessment of the island marble butterfly, the results of which were
inconclusive (Potter 2015b, in litt.).
The handling of adult butterflies for scientific purposes has been
evaluated for effects on populations elsewhere in western North America
(Singer and Wedlake 1981; Gall 1984). Murphy (1988, p. 236) reported
that MRR work by others resulted in about 10 percent mortality to the
endangered mission blue butterfly (Icaricia icarioides missionensis);
however, studies by Singer and Wedlake (1981, entire) with other
butterflies resulted in less than 2 percent of the marked butterflies
being recaptured, suggesting that mortality from handling the
butterflies may have been a factor.
Peterson's 2008 MRR study may have resulted in unintended injury or
mortality to island marble butterfly individuals, but we have no
evidence to suggest that the study resulted in population- or species-
level effects. Surveyors were unable to recapture 38 percent of the
handled individuals during the short duration of this research, but
whether this research directly increased mortality for the handled
individuals is unknown. Several outcomes could have led to this low
recapture rate: The butterflies may have fully matured after completing
their life cycle and died during this period; they may have been
injured during handling and died following release; they may have
become more susceptible to other stressors after handling (e.g.,
predation); or they may have simply eluded recapture. Based on the
relative encounter rate for the island marble butterfly that was
measured during subsequent years (see ``Abundance,'' above, for
additional information), this research does not appear to have
contributed to a constriction in the range of the species or a decline
in the abundance of individuals.
The probability of numerous future collections of live island
marble butterflies for research purposes is low because all researchers
who study the island marble butterfly work collaboratively with the
Service, NPS, and WDFW, and are aware of the very low and declining
number of individual butterflies. Any research proposal requiring the
collection and removal of live island marble butterflies from the
population is carefully reviewed to determine whether the conservation
benefit to the species outweighs the loss of individuals.
Summary of Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
We continue to find that overutilization does not have a
population-level impact on the island marble butterfly for the
following reasons: The lack of evidence of commercial or recreational
collection of island marble butterflies; our conclusion that handling
of the species during the 2008 MRR study did not result in documented
negative effects to island marble butterfly populations; and the small
number of individuals collected for genetic evaluation.
Factor C. Disease or Predation
Disease
There is a single report of disease affecting the island marble
butterfly (Miskelly 2004, p. 35). We discussed this observation with
the author and discovered that this was an isolated event and that the
mortality was likely attributable to causes other than disease
(Miskelly 2015a, in litt.). Therefore, there is no evidence to suggest
that disease is currently a threat to the island marble butterfly.
Direct Predation
Predation is a risk for island marble butterflies during all stages
of their life cycle, although mortality is highest during the earliest
stages of life: Egg to first instar (Lambert 2011, p. 92). A study
conducted from 2005 through 2008 on survivorship of the island marble
butterfly identified high levels of mortality attributable to predation
by spiders and, to a lesser extent, paper
[[Page 26799]]
wasps (Polistes spp.) (Lambert 2011, p. 117). Two species of spider,
Pardosa distincta and Zelotes puritanus, both native to Washington
State, prey on adult island marble butterflies and may also account for
a large proportion of the predation on eggs and larvae (Lambert 2011,
p. 100; Crawford 2015, in litt.). The paper wasp common to American
Camp is the nonnative Polistes dominula (Miskelly 2015b, in litt.),
discovered in the State of Washington in 1998 (Landolt and Antonelli
1999, entire).
Direct predation of eggs and larvae was the greatest source of
mortality in this 4-year study, affecting 47 percent of all individuals
tracked (Lambert 2011, p. 99). Mortality levels attributable to direct
predation varied depending on the larval host plant used, with almost
80 percent mortality attributable to direct predation on Menzies'
pepperweed and approximately 40 percent on field mustard (Lambert 2011,
p. 117). These differences are likely attributable to variation in the
structure and growth form of the larval host plants that can facilitate
access by predators (Lambert 2011, p. 100).
In addition, predation on island marble butterfly larvae by spiders
and wasps increases as the season advances (Lambert 2015d, p. 14). This
increase is likely because: (a) As spiders mature, they are more
effective at locating and consuming the larvae; and (b) wasps increase
in number as the season progresses (Reeve 1991, pp. 104-106), and the
predation pressure they exert on their prey species increases with
these increased numbers. Later emergence of island marble butterflies
has been observed to correlate closely with increased predation
pressure on island marble larvae; in the 2015 field season, when
emergence was notably late, none of the 329 individuals tracked from
egg through their larval development survived to form a chrysalis
(Lambert 2015d, p. 14) (see Cumulative Effects, below, for additional
discussion). Predation on adult island marble butterflies by birds and
spiders has been observed anecdotally, although no effort has been made
to quantify mortality attributable to predation on adults (Lambert
2011, p. 90; Vernon and Weaver 2012, p. 10). We found no evidence to
suggest that predation by small mammals or other vertebrate predators
presents a threat.
Direct predation of island marble butterfly eggs and larvae is
ongoing where the species occurs (at American Camp) and is expected to
continue into the future. Direct predation of eggs and larvae is a
significant cause of mortality for the island marble butterfly,
consistently accounting for more than 45 percent of deaths for tracked
individuals (Lambert 2011, p. 99; Lambert 2015d, p. 14). Native spiders
are responsible for a significant proportion of observed predation, and
the island marble butterfly presumably coexisted for hundreds or
thousands of years with these spiders. However, the small and declining
numbers of island marble butterflies, under pressure from habitat loss
and other threats, now cannot tolerate what may once have been a
sustainable rate of natural predation. The threat of direct predation
affects the island marble butterfly at the individual, population, and
species levels (see Factor E discussion, below, for more information).
Incidental Predation
Incidental predation by browsing black-tailed deer also is a common
source of mortality for island marble butterfly eggs and larvae
(Lambert 2011, pp. 93-97; Lambert 2015d, pp. 17-18). As discussed above
under Factor A, female island marble butterflies select oviposition
sites on or near the tips of the inflorescences of the larval host
plants, which is the same portion of the plant that deer prefer to
browse (Lambert 2015c, in litt.). Similar to rates of direct predation,
each species of larval host plant is correlated with differing levels
of mortality attributable to deer browse. Incidental predation by deer
was highest on field mustard, which accounted for slightly more than 40
percent of mortality tracked for this larval host plant over the course
of the 4-year study (Lambert 2011, p. 117). Mortality attributable to
deer browsing was less than 10 percent for both Menzies' pepperweed and
tumble mustard (Lambert 2011, p. 117).
In nearly every report provided to the Service, deer browsing has
been identified as particularly problematic for the island marble
butterfly at American Camp as well as throughout the species' former
range, where browsing deer continue to degrade the butterfly's habitat
(Miskelly and Fleckenstein 2007, p. 6; Miskelly and Potter 2009, pp.
11, 15; Hanson et al. 2009, pp. 4, 13, 20; Hanson et al. 2010, pp. 21-
22; Potter et al. 2011, pp. 5, 13; Lambert 2011, p. 104; Lambert 2014a,
entire; Vernon and Weaver 2012, p. 9; Weaver and Vernon 2014, p. 10;
Lambert 2014a, p. 3; Lambert 2015d, pp. 17-18; Vernon 2015a, p. 12).
Incidental predation by deer is a significant cause of mortality of the
island marble butterfly at American Camp (Lambert 2014a, p. 3).
Incidental predation by deer is a threat of increasing severity within
American Camp, where it affects the island marble butterfly at the
individual, population, and species level; outside American Camp, this
source of habitat degradation is ongoing throughout the formerly
occupied range of the species because of the apparent increase in deer
numbers throughout the San Juan Islands (Milner 2015, in litt.;
McCutchen 2016, in litt.).
Although incidental predation by other herbivores has not been as
rigorously quantified as it has been for black-tailed deer, the
negative effects of livestock on occupied larval host plants cannot be
discounted (Miskelly and Fleckenstein 2007, p. 5; Miskelly and Potter
2009, pp. 9, 11, 15; Hanson et al. 2009, pp. 18, 20; Hanson et al.
2010, pp. 5, 16, 21; Potter et al. 2011, p. 13; Vernon 2015c in litt.,
entire). Incidental predation by livestock, brown garden snails, and
European rabbits is possible where the range of the island marble
butterfly overlaps with these species. However, in the case of European
rabbits, only two documented instances exist of rabbits consuming
plants with eggs or larva on them (Lambert 2015d, p. 17). Suitable
island marble butterfly larval habitat is closely monitored at American
Camp, so while consumption of occupied larval host plants by European
rabbits does occasionally take place, it is currently rare, is
geographically circumscribed, and does not have a population-level
impact to the species. The existing information does not indicate that
incidental predation by livestock, brown garden snails, and European
rabbits is occurring at a rate that currently causes population-level
impacts to the island marble butterfly.
Conservation Efforts To Reduce Disease or Predation
As described above under ``Habitat Conservation and Restoration,''
the Service and NPS installed deer exclusion fencing in American Camp
from 2013 to 2016 to reduce browsing by black-tailed deer on the larval
host plants field mustard and tumble mustard. The fencing was placed to
reduce incidental predation, as well, by protecting areas where larval
host plants are most likely to be occupied by island marble butterfly
eggs and larvae.
The Service has supported ongoing research into the effects of deer
exclusion fencing on island marble butterfly survival. The first deer
exclusion fencing was erected in three locations of American Camp in
2013. Areas immediately adjacent to the fenced habitat with similar
structure, quality, and connectivity as the fenced habitat were left
unfenced as control plots. First-year monitoring of deer
[[Page 26800]]
exclusion areas showed that 74 percent of eggs tracked survived to
first instar in the fenced area compared with 41 percent survival to
first instar in the control plots (Lambert 2014a, p. 6). In 2014,
additional deer exclusion fencing was installed, and different types of
exclusion fencing were compared. Wire-mesh fencing was found to be
effective at preventing incidental predation by deer, while electric
fencing was determined to be largely ineffective at excluding deer,
although mortality from deer in electric-fenced areas was lower than in
previous years (Lambert 2015d, pp. 17-18). Deer exclusion fencing has
emerged as an important tool for protecting eggs and early instar
larvae from consumption by deer, especially early in the flight season
when survivorship is expected to be the highest (Lambert 2015d, p. 19;
Lambert 2016a, pp. 3, 27).
Summary of Disease and Predation
The best available information does not indicate that disease is a
threat to the island marble butterfly. However, a substantial amount of
research completed since 2006 clearly documents the effects of
predation. Direct and incidental predation rates, together, account for
the vast majority of the recorded deaths of island marble butterfly
eggs and larvae at American Camp. Although deer exclusion fencing at
American Camp has been an important tool for reducing mortality due to
incidental consumption since 2013, the number of island marble
butterflies observed continues to be low. No conservation measures have
yet been identified to address the threat of predation from paper wasps
and spiders. Taken together, all forms of predation have pervasive,
population-level impacts on the island marble butterfly.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms ameliorate or exacerbate the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species . . . .'' In
relation to Factor D under the Act, we interpret this language to
require the Service to consider relevant Federal, State, and tribal
laws, regulations, and other such mechanisms that may ameliorate or
exacerbate any of the threats we describe in threat analyses under the
other four factors, or otherwise enhance conservation of the species.
We give strongest weight to statutes and their implementing regulations
and to management direction that stems from those laws and regulations.
An example would be State governmental actions enforced under a State
statute or constitution, or Federal action under statute.
Federal Laws and Regulations
American Camp, as part of San Juan Island National Historical Park,
is managed under the National Park Service's Organic Act and
implementing regulations. The National Park Service Organic Act of
1916, as amended (54 U.S.C. 100101 et seq.), states that the National
Park Service ``shall promote and regulate the use of the National Park
System . . . to conserve the scenery, natural and historic objects, and
wild life in the System units and to provide for the enjoyment of the
scenery, natural and historic objects, and wild life in such manner and
by such means as will leave them unimpaired for the enjoyment of future
generations'' (54 U.S.C. 100101(a)). Further, 36 CFR 2.1(a)(1)(i) and
(a)(1)(ii) specifically prohibit collection of living or dead wildlife,
fish, or plants, or parts or products thereof, on lands under NPS
jurisdiction. This prohibition on collection extends to the island
marble butterfly where it exists on NPS-managed lands. In addition,
under the general management plan for San Juan Island National
Historical Park, NPS is required to follow the elements of the
conservation agreement (NPS 2008, p. 73). This includes restoring
native grassland ecosystem components at American Camp, avoiding
management actions that would destroy host plants, avoiding vegetation
treatments in island marble butterfly habitat when early life-stages
are likely to be present, and implementing a monitoring plan for the
species (Pyle 2006, pp. 10-12).
The Bureau of Land Management (BLM) owns the 27-ac (11-ha) Cattle
Point Lighthouse property east of American Camp and Cattle Point
Natural Resource Conservation Area. This site was formerly occupied by
island marble butterflies, is proximal to occupied habitat on American
Camp, and contains suitable habitat for the species. The Cattle Point
Lighthouse property is part of the San Juan Islands National Monument
established by Presidential proclamation on March 25, 2013, under the
American Antiquities Act of 1906 (54 U.S.C. 320301 et seq.). This
proclamation specifically identifies the island marble butterfly and
states that protection of the lands in the San Juan Islands will
maintain their historical and cultural significance and enhance their
unique and varied natural and scientific resources, for the benefit of
all Americans. Under this proclamation, the monument is being managed
as part of the National Landscape Conservation System, requiring that
the land be managed ``in a manner that protects the values for which
the components of the system were designated'' (16 U.S.C. 7202(c)(2)).
The first resource management plan for the National Monument is still
in development, so specific regulatory protections for the species and
its habitat have not yet been established. Nevertheless, anthropogenic
threats at this site are unlikely given its current designation as a
National Monument.
The island marble butterfly is also listed as a sensitive species
for the purposes of the BLM's Sensitive Species Policy (BLM 2008, p. 3;
USFS 2015, entire). This policy directs the BLM to initiate
conservation measures that reduce or eliminate threats and minimize the
likelihood of listing under the Act, but until the resource management
plan for the National Monument is complete, the BLM has not identified
the required conservation measures. At this time, it is unclear what
protections, if any, these existing regulatory mechanisms will confer
to the island marble butterfly.
State Laws and Regulations
State laws and regulations that apply across San Juan and Lopez
Islands include provisions to limit collection of butterflies for
scientific purposes, but no specific protections to island marble
butterfly habitats. The island marble butterfly is currently classified
as a candidate species by the State of Washington (WDFW 2015a, p. 2).
Candidates are those species considered by Washington State to be
sensitive and potentially in need of protection through the process of
designation as endangered, following procedures established by the
Washington Administrative Code (WAC) (220-610-110). However, candidates
are not afforded any specific regulatory protections (Potter 2015c, in
litt.). The island marble butterfly is afforded limited State
regulatory protections from overcollection as the State of Washington
requires a scientific collection permit for handling or collecting any
fish, or wildlife, their nests, or eggs for scientific purposes (WAC
220-200-150; Revised Code of Washington (RCW) 77.32.240).
The island marble butterfly was identified as critically imperiled
in the Washington State Comprehensive Wildlife Conservation Strategy
(WDFW
[[Page 26801]]
2005, pp. 219, 314, 336-337). Since 2005, WDFW has retired the
Comprehensive Wildlife Conservation Strategy and incorporated it into
Washington's State Wildlife Action Plan (SWAP). Although the SWAP
addresses the island marble butterfly's conservation status, identifies
it as a ``species of greatest conservation need,'' and recommends
conservation actions (WDFW 2015b, p. 3-39), the SWAP is not a
regulatory mechanism.
WDNR owns the Cattle Point Natural Resources Conservation Area
consisting of 112 acres directly to the east of American Camp, a
portion of which provides potentially suitable habitat for island
marble butterflies. Natural resource conservation areas are managed to
protect outstanding examples of native ecosystems; habitat for
endangered, threatened, and sensitive plants and animals; and scenic
landscapes. Removal of any plants or soil is prohibited unless written
permission is obtained from WDNR (WAC 332-52-115).
Local Laws and Regulations
American Camp is the only area known to be occupied by the island
marble butterfly, and because the area is managed by NPS under the
National Park Service's Organic Act and implementing regulations, local
laws and regulations governing land use do not apply. However, the
following local laws and regulations may provide some benefit to the
island marble butterfly, should the species expand its range or
recolonize suitable habitat areas outside American Camp.
The Washington State Growth Management Act of 1990 (GMA) requires
all jurisdictions in the State to designate and protect critical areas
(RCW 36.70A). The State defines five broad categories of critical
areas, including: (1) Wetlands; (2) areas with a critical recharging
effect on aquifers used for potable water; (3) fish and wildlife
habitat conservation areas; (4) frequently flooded areas; and (5)
geologically hazardous areas (RCW 36.70A.030). The upland prairie
habitat type that island marble butterflies may use, but are not
restricted to, is considered both a fish and wildlife habitat
conservation area and an area with a critical recharging effect on
aquifers under the GMA. Identification as a fish and wildlife habitat
conservation area mandates that each county within Washington State
preserve and protect the fish and wildlife associated with each habitat
conservation area by developing policies and regulations to protect the
functions and values of critical areas. Within counties, the mandate to
protect and regulate critical areas applies to all unincorporated
areas. In addition, incorporated cities within counties are required to
address critical areas within their ``urban growth area'' (UGA; the
area in which urban growth is encouraged by the municipal government)
independently. The only incorporated city within San Juan County is
Friday Harbor, which is located outside of NPS-owned land on San Juan
Island and outside of habitat currently occupied by the island marble
butterfly. The Friday Harbor Comprehensive Plan provides no specific
protections for animal species that are not listed as endangered or
threatened under State or Federal law; however, Upland Category III may
confer some benefits to the species based on conservation status of the
species.
San Juan County encompasses the range of the island marble
butterfly. The County regulates critical areas through a Critical Areas
Ordinance, which mandates protection for species listed under the Act
through San Juan County Critical Areas Ordinance (section 18.30.110,
Fish and Wildlife Habitat Conservation Areas). The Critical Areas
Ordinance also identifies species of local importance, including the
island marble butterfly (San Juan County 2018, p. 34), and provides
protection for the island marble butterfly by requiring that
development applications for areas determined to be occupied by the
island marble butterfly develop a habitat management plan consistent
with County recommendations for the conservation of the island marble
butterfly prior to permitting. The San Juan County Comprehensive Plan
recommends that property owners with occupied island marble butterfly
habitat avoid the use of insecticides and herbicides, limit grazing and
agricultural disturbance, and protect areas with larval host plants
during the development process (San Juan County 2018, pp. 51, 56).
However, the conservation recommendations are not comprehensive enough
to prevent local extirpation of the island marble butterfly because
they do not address all of the stressors influencing its persistence
(e.g., landscaping, permanent landscape conversion, mowing, etc.), as
evidenced by the complete loss of occupied island marble butterfly
habitat within areas developed since 2006 (see ``Development,'' above,
under Factor A).
In addition, the San Juan County Comprehensive Plan concentrates
urban density within UGAs in order to preserve the rural nature of the
San Juan archipelago (San Juan County 2010, entire). We considered the
plan in our 2006 12-month finding (71 FR 66292; November 14, 2006),
concluding that the restriction of high-density development would lead
to the maintenance of suitable habitat on Lopez and San Juan Islands.
While preserving the low-density agricultural environment on San Juan
and Lopez Islands partially prevents the direct conversion of suitable
island marble butterfly habitat to other incompatible uses (e.g.,
impermeable surfaces, manicured lawns, residential housing), new
evidence indicates that despite these planning efforts, island marble
butterfly habitat has been severely curtailed rangewide since 2006, due
to a variety of factors (e.g., mowing, landscaping, or removal of host
plants) (Miskelly and Potter 2005, p. 6; Miskelly and Fleckenstein
2007, p. 6; Potter 2015a, in litt.).
Summary of Existing Regulatory Mechanisms
The island marble butterfly and its host plant are afforded
substantial regulatory protections from anthropogenic threats at
American Camp through NPS regulations and the current general
management plan for San Juan Island National Historical Park. In
addition, State- and County-level regulatory mechanisms that influence
development and zoning on San Juan and Lopez Islands are generally
beneficial to suitable habitat that could be occupied by the island
marble butterfly in the future. However, this impressive suite of
regulatory mechanisms has not prevented the extirpation of other
populations, and the species remains in precarious shape with only one
remaining known location. Therefore, we conclude that the existing
Federal, State, and local regulatory mechanisms provide some benefits
to the island marble butterfly and its habitat, but do not sufficiently
ameliorate the threats to the species such that it does not meet the
definition of an endangered species.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Under Factor E, we evaluate the island marble butterfly's small
population size and its vulnerability to stochastic events, vehicular
collisions, insecticide application, late emergence of adult
butterflies, and climate change.
Small Population Size and Vulnerability to Stochastic Events
Since its rediscovery in 1998, the island marble butterfly has been
[[Page 26802]]
documented to have a narrow distribution, which has become increasingly
constrained as secure habitat has been reduced or destroyed throughout
the butterfly's range (Miskelly and Potter 2005, entire; Miskelly and
Fleckenstein 2007, entire; Miskelly and Potter 2009, entire; Hanson et
al. 2009, entire; Hanson et al. 2010, entire; Potter et al. 2011,
entire; Vernon and Weaver 2012, entire; Weaver and Vernon 2014, entire;
Potter 2015a, in litt.; Vernon 2015a, entire). Declining numbers for
the island marble butterfly have been documented during annual
monitoring at American Camp that has taken place from 2004 through 2015
(see ``Abundance,'' above), and the species now appears to be
restricted to a single known population centered on American Camp.
Compared to large populations, small populations are
disproportionately affected by environmental, demographic, and genetic
stochasticity, and thus face greater risk of extinction (Frankham 1996,
p. 1506; Saccheri et al. 1998, entire; Harper et al. 2003, pp. 3349,
3354). Environmental stochasticity is the variation in birth and death
rates from one season to the next in response to weather, disease,
competition, predation, or other factors external to the population
(Shaffer 1981, p. 131). For example, drought or predation in
combination with a low population year could result in extirpation, and
butterflies are known to be sensitive to environmental variation,
increasing the influence of this factor (Weiss et al. 1993, pp. 267-
269). Stochastic environmental events can be natural or human-caused.
Demographic stochasticity refers to random variability in survival
or reproduction among individuals within a population (Shaffer 1981, p.
131). This random variability has a proportionately large effect on
small populations, such that any loss of beneficial alleles (genes that
provide for more successful reproduction and survival) may result in a
rapid reduction in fitness, making small populations much more likely
to go extinct than large populations (Frankham 1996, p. 1507). Genetic
stochasticity, or genetic drift, describes random changes in the
genetic composition of a population that are not related to systemic
forces such as natural selection, inbreeding, or migration. In small
populations, genetic stochasticity is more likely to result in reduced
fitness and ultimately a lower number of individuals contributed to
each successive generation. Small, narrowly distributed populations
generally have lower genetic diversity than larger populations, which
can result in less resilience to changing environmental conditions.
Because the island marble butterfly persists in low numbers, loss
of a portion of the remaining population could have disproportionately
negative effects. Storm surges that destroy nearshore habitat
containing overwintering island marble butterfly chrysalids may further
deplete the genetic diversity of the island marble butterfly.
Similarly, in grassland habitat, a poorly timed or uncontrolled fire
could destroy a large portion of the remaining population. The effect
of predation, which has always been at least a baseline limiting factor
for the island marble butterfly, is magnified when there are so few
individuals left. Additional stochastic events that could potentially
be devastating include a late-spring weather abnormality, such as an
extended hard freeze or a powerful storm during the flight season; a
year in which predator populations were unusually high; or introduction
of a novel predator. Given that the very small population at American
Camp is likely the only remaining population of the species, we
conclude that small population size makes it particularly vulnerable to
a variety of likely stochastic events, and this constitutes a threat to
the island marble butterfly at the individual, population, and species
levels.
Vehicular Collisions
Habitat occupied by the island marble butterfly within American
Camp is bisected by Cattle Point Road, a highway that is the only point
of access for a small residential community at the southeastern tip of
San Juan Island (approximately 100-150 housing units) and, as such, is
routinely driven by the residents. The highway runs along the shoulder
of Mount Finlayson, a landscape feature that male island marble
butterflies typically follow when patrolling for females (Lambert
2016b, pers. comm.). While there have been no specific reports of
island marble butterfly road kills, the presence of the highway within
occupied habitat exposes the species to potential vehicle collisions.
Few studies provide detail on the scale of vehicle-caused mortality for
invertebrate species, and even fewer specifically examine butterfly
mortality or the effects of traffic on individual butterfly species
(Seibert and Conover 1991, p. 163; Munguira and Thomas 1992, entire;
Rao and Girish 2007, entire).
One peer-reviewed study that examined vehicular mortality for
butterflies found that a species in the same family as the island
marble butterfly, Pieris rapae, was more likely to be struck and killed
by vehicles in comparison to the other more sedentary species in the
study, with 7 percent of a local population killed by cars in a 44-day
period (Munguira and Thomas 1992, p. 325). The study was conducted
along ``main roads'' in the United Kingdom that connected relatively
large cities (Munguira and Thomas 1992, p. 317); thus, it is likely
they had more traffic than the highway at American Camp. While the
authors of the study did not find the percentage of the population
killed by vehicles to be significant in comparison to mortality caused
by other natural factors affecting their survival (Munguira and Thomas
1992, p. 316), the loss of individual island marble butterflies could
have disproportionately large negative effects on the species as a
whole because of its restricted range and small population size.
Male island marble butterflies are attracted to white (ultraviolet-
reflecting) objects that may resemble females and have been observed to
investigate white flowers (e.g., field chickweed and yarrow), white
picket fences, and white lines painted on the surface of roads (Lambert
2011, p. 47). The highway through American Camp has fog lines that are
painted white that could be attractive to adult butterflies, thereby
increasing their risk of being killed by vehicles. The centerlines on
the highway are painted yellow.
Given the presence of a highway within the single remaining site
occupied by island marble butterflies, and their attraction to white
road stripes that are present along the Cattle Point Road edges, we
expect that some vehicular mortality is likely. However, we cannot
estimate the severity of this stressor, as vehicular mortality has not
been specifically studied for the island marble butterfly or documented
at American Camp. Therefore, while there is the potential for mortality
resulting from vehicular collisions, the best available information
does not indicate that vehicular collision currently has an individual-
, population-, or species-level impact to the island marble butterfly.
Insecticide Application
The best available information does not indicate any insecticide
use in proximity to areas that are currently known to be occupied by
the island marble butterfly at American Camp. However, remnant patches
of potentially suitable habitat for the species are located within a
matrix of rural agricultural lands and low-density residential
development, where
[[Page 26803]]
insecticides may be used. One such insecticide that has the potential
to adversely affect the island marble butterfly if applied during its
larval phase is Bacillus thuringiensis var. kurstaki (Btk). This
insecticide, derived from a common soil bacterium, is used in a wide
range of settings, including organic agriculture, for the control of
lepidopteran (butterfly and moth) pest species (National Pesticide
Information Center 2015, p. 1; Oregon Health Authority 2015, p. 1). In
forestry, it is used broadly for the control of the Asian and European
gypsy moth species (Lymantria dispar, and L. dispar dispar,
respectively) (see WSDA 2015, entire). Btk is also more generally
applied for other lepidopteran pest species, such as tent caterpillars
(Malacosoma spp.).
Btk has the potential to kill the island marble butterfly larvae if
applied in close proximity and upwind of an occupied site. Spraying of
Btk has had adverse effects to nontarget butterfly and moth species
(Severns 2002, p. 169; Wagner and Miller 1995, p. 19), with butterfly
diversity, richness, and abundance (density) reduced for up to 2 years
following the application of Btk (Severns 2002, p. 168). One study
demonstrated that most nontarget lepidopteran species may be more
susceptible to Btk than target species such as Asian and European gypsy
moths or western tent caterpillars (Haas and Scriber 1998). For
nontarget lepidopterans, the early instar stages of larvae are the most
susceptible stage (Wagner and Miller 1995, p. 21).
Large-scale application of Btk in Washington State is done in a
targeted fashion in response to positive trapping of pest species. In
most years, Btk application is conducted at the scale of hundreds of
acres per year, although in years when detection of pest species are
high, such as in 2015, application of Btk may be scaled up to thousands
of acres in response (WSDA 2015, p. 1). Large-scale application of Btk
does not normally overlap with areas where the island marble butterfly
is known to occur within American Camp, although if pest species were
detected in close proximity and if the target species is active at the
same time as larvae of the island marble butterfly, the effect of Btk
treatment could be detrimental. Because the island marble butterfly
produces a single brood per year, has a spring flight season, and has
developing larvae during the summer insecticide application period,
this species is more likely to be susceptible to the adverse effects of
Btk than butterfly species with later flight and developmental periods
or those that produce multiple broods per year. Btk is commonly used to
control tent caterpillars and is likely to have been used on San Juan
Island (Potter 2015d, in litt.), although the effect on the island
marble butterfly at American Camp is not documented. At this time, the
best available information does not indicate that Btk has been applied
at or adjacent to any location where island marble butterflies are
known to occur.
We recognize that the use of insecticides could have a negative
impact on larvae of the island marble butterfly if applied in such a
way that individuals were exposed. However, there is no documented
exposure to insecticide use in the island marble butterfly at this
time. While there is the potential for high levels of mortality
resulting from insecticide exposure, we conclude that insecticide use
is not having a known impact on the island marble butterfly,
principally because of the low likelihood of exposure at American Camp.
Late Emergence of Adult Butterflies
Since regular transect surveys for the island marble butterfly
began in 2004, the first date of the flight period has shifted an
average of approximately 9 days later in the year (USFWS 2016,
unpublished data). The reason for this change is unclear, and the
existing time-series is too brief to ascertain whether this change is a
trend or part of natural variability on a longer time scale. For
example, no clear correlation exists between average winter
temperatures and the beginning of the island marble flight season and
the shift toward later emergence between 2004 and 2016. Later emergence
cannot currently be attributed to climate change, although temperature
may play a role. When conditions inside the captive-rearing lab for
island marble butterflies were cooler than the ambient temperature in
2015, butterflies emerged later than the wild population (Shrum 2015b,
in litt.). The temperature was increased inside in 2016, and the
captive and wild adults emerged at the same time (Weaver 2015b, in
litt.; Shrum 2016, in litt.). Other environmental conditions, including
moisture, likely influence emergence time as well (Tauber et al. 1998,
entire).
Ongoing research has recently detected a steep increase in
mortality for late-season eggs and larvae compared to the mortality of
early-season eggs, with none of the larvae observed in study plots
surviving to the fifth instar in 2015 (Lambert 2015d, p. 14). Only a
portion of the mortality documented was attributable to starvation (25
percent); the greatest cause of mortality was attributable to direct
predation (60 percent) (Lambert 2015d, p. 14; see discussion above
under Factor C). The single, small population of island marble
butterflies likely cannot sustain the increased late-season predation
pressure, and probable survival of fewer offspring, over multiple
years.
Climate Change
Our analyses under the Act include consideration of ongoing and
projected changes in climate. The majority of climate models for the
Pacific Northwest region predict wetter winters, with an increase in
the proportion of precipitation falling as rain rather than snow due to
increasing ambient temperature, and drier summers as a result of
reduced snowpack and ensuing hydrologic drought (Mote and
Salath[eacute] 2010, p. 48). No downscaled climate models specific to
the San Juan Island archipelago are available, and San Juan Island is
not reliant on snowpack for its water. The portion of San Juan Island
where the known population of the island marble butterfly occurs is in
the rain shadow of mountain ranges on Vancouver Island, Canada, and in
Washington State, resulting in weather patterns commonly drier than
much of the rest of the Pacific Northwest (Mass 2009, entire). While
the San Juan Island archipelago may be subject to the increasing
average annual temperatures associated with climate change, it is
unclear how changing temperatures will affect the island marble
butterfly.
One predicted stressor associated with climate change for
herbivorous (plant-eating) insect species is the potential for the
development of phenological asynchrony (a mismatch in timing) between
insects and their larval host plants (Bale et al. 2002, p. 8). If an
herbivorous insect emerges earlier or later than the optimal stage of
its larval host plant, the insect may not be able to find plants at the
right stage for egg laying, or the insect's larvae may not have
adequate food resources. If the insect emerges earlier than its larval
host plant, the plants may not be detectable, leaving the animal with
no place to lay her eggs, or the plants may be too small to provide
enough forage for larvae, leading to starvation. Conversely, if the
insect emerges when the plant is at a later phenological stage, eggs
may be laid on a larval host plant that has matured to the point that
plant tissues are too tough for the larvae to consume, or the plant may
die before the insect has acquired enough resources to survive to the
pupation stage. The island marble butterfly is an early-flying species,
generally emerging in April and immediately mating and laying eggs on
the larval host plants that
[[Page 26804]]
are available. This strategy ensures that the host plants are young
enough to provide tender plant tissue for first instar larvae, which
have mouthparts incapable of consuming anything but the high-moisture
flower buds. In the absence of access to tender buds, early instar
larvae die from desiccation (Lambert 2011, p. 12). Although evidence
exists that some larvae of late-emerging island marble butterflies have
suffered starvation (Lambert 2015d, p. 14), perhaps as a result of
mismatch between butterfly and food-plant phenology, no recurring
pattern in such mismatch exists now that can be associated with climate
change. However, monitoring of phenology and survival in the island
marble butterfly is ongoing and may shed light on this relationship in
the future.
Sea-level rise associated with climate change is expected to
continue as polar ice melts, leading to an increase in ocean volume
(Adelsman et al. 2012, p. 82). The warming climate is also expected to
lead to rising ocean temperatures resulting in thermal expansion of the
water, which will also increase the volume of the ocean (Dalton et al.
2013, p. 70). Both of these effects of climate change are expected to
lead to rising sea level, which will have the direct effect of
increasing the impacts of storm surges and flooding events in low-lying
areas, such as the nearshore lagoon habitat of the island marble
butterfly (MacLennan et al. 2013, pp. 4-5; Vose et al. 2014, p. 381;
Friends of the San Juans 2014, p. 7; Whitman and MacLennan 2015, in
litt.; NOAA 2015a, entire; NOAA 2015b, entire). Because the nearshore
habitat is barely above sea level, rise in sea level increases the risk
of inundation and direct mortality for island marble butterflies
overwintering as chrysalids in low-lying nearshore habitat. Powerful
storm surges have historically deposited large amounts of coarse
sediment and driftwood in areas occupied by Menzies' pepperweed (an
estimated 5 to 8 percent of habitat occupied in 2006) and where a
number of island marble butterflies were overwintering as chrysalids,
leading to low numbers of individuals detected in nearshore habitat in
years following a storm surge event (Lambert 2011, pp. 99, 145-146;
Lambert 2015f, in litt.). Due to the small number of individuals
remaining, mortality and habitat loss resulting from storm surges
likely has a population-level impact on the island marble butterfly,
and we expect these impacts to increase over time as an effect of
global climate change.
While some effects of global climate change, such as sea-level rise
and storm intensity, are expected to be nearly universal, warming
associated with climate change is expected to be variable or even
patchy, depending on localized weather patterns (e.g., patterns
influenced by oceanographic phenomena such as El Ni[ntilde]o and La
Ni[ntilde]a) (Adelsman et al. 2012, p. 37). The Pacific Northwest
region of the United States abuts the eastern edge of the Pacific
Ocean, which warms and cools in sync with the Pacific Decadal
Oscillation (Mantua and Hare 2002, entire). Given the unclear direction
of climate trends in the San Juan archipelago, we cannot conclude that
the island marble butterfly is exhibiting phenological changes such as
later emergence as a result of climate change, or that the species will
do so in the future.
Climate conditions that affect phenology in a given year can have
important impacts to the species, however. Cooler temperatures are
associated with later emergence of butterflies reared in captivity
(Weaver 2015b, in litt.), and late emergence leads to a spike in late-
season predation on island butterfly larvae, when spider and wasp
populations are greatest (see discussions above under Factor C, and
above under ``Late Emergence of Adult Butterflies''). Compared with an
abundant species with numerous, well-distributed populations, the
island marble butterfly's small remaining population is far more
vulnerable to such fluctuations in mortality.
Conservation Efforts To Reduce Other Natural or Manmade Factors
Affecting Its Continued Existence
The Service, NPS, and other partners have been implementing
multiple conservation efforts in an attempt to ameliorate the threats
posed by small population size, vulnerability to stochastic events, and
insecticide applications. No conservation efforts currently address
collisions with vehicles or the effects of climate change. Below we
summarize the conservation measures that have been implemented by NPS,
WDFW, University of Washington researchers, and conservation partners
on San Juan Island to address the threats to the island marble
butterfly described above under Factor E.
The Service, NPS, and other partners have conducted conservation
efforts to address the effects of small population size and
vulnerability to stochastic events on the island marble butterfly since
2008. Specifically, NPS and other partners began exploring methods for
captive-rearing island marble butterflies in 2008. In 2009, 16 island
marble butterfly individuals were rescued from a construction site,
reared to emergence as adult butterflies, and released in the spring of
2010 (Vernon 2015d, p. 2). In 2010, more individuals were reared as
part of a food preference experiment (Trapp and Weaver 2010, entire),
and 32 adults were released in 2011 (Vernon 2015d, p. 5). These
opportunistic events demonstrated that rescue, rearing, and releasing
of island marble butterflies could be successful. A handbook based on
these captive-rearing events and more recent efforts was developed to
guide captive-rearing and release efforts for the island marble
butterfly (Vernon 2015d, entire).
In 2013, continued decline in the number of island marble
butterflies observed in the wild led to the rescue, captive-rearing,
and release of the species in an effort to improve survivorship and
reverse the trend of declining numbers, and provide a safety net
against stochastic events. Forty-seven individuals successfully formed
chrysalids, and 40 adult island marble butterflies emerged in the
spring of 2014, and were released at American Camp (85 percent
survival) (Vernon 2015d, p. 3). NPS has scaled up and streamlined the
captive-rearing program. In 2014, NPS converted an outbuilding into a
rearing facility, and 89 eggs and larvae were brought in for captive-
rearing. Of those, 75 adult island marble butterflies emerged (84
percent survival) in the spring of 2015, and were released at American
Camp (Silahua 2015, in litt.). In 2015, 126 eggs and larvae were
brought in for captive-rearing, 114 of which survived to become
chrysalids (Silahua 2015, in litt.). The productivity of the captive
rearing facility has continued to increase in subsequent years; in
2016, 111 adult island marble butterflies were released; in 2017, 136;
and in 2018, 158 adults were released (SJINHP 2018, in litt.). In
total, more than 500 adult island marble butterflies have been released
back into the wild through this program (SJINHP 2018, in litt.).
Although the number of adult island marble butterflies recorded
during annual surveys remains small (fewer than 30 butterflies were
observed each year during monitoring for the 2014 and 2015 flight
seasons), the captive-rearing effort has likely provided crucial
support to the population remaining in the wild and will remain
necessary in the future. We note, that there is no data available
allowing a precise characterization of the success released individuals
have in contributing to the overall population of the species. However,
this ongoing conservation effort to address small population size
[[Page 26805]]
and vulnerability to stochastic events is not without risk and does not
ameliorate other threats to the species in the long term. For example,
in 2015, individuals reared in captivity emerged late in the flight
season (on or around May 13) (Weaver 2015b, in litt.), and available
data suggest that the majority of the offspring of these captive-reared
individuals died as a result of high late-season predation rates
(Lambert 2015d, p. 14; see discussion under Factor C, above). In 2016,
the date of emergence in the captive-rearing facility was better
calibrated to ambient environmental temperatures by adjusting the
temperature in the facility to match those of the surrounding outdoor
area, but there are likely to be other unforeseen challenges to
successful captive-rearing.
Conservation efforts to reduce natural or manmade factors include
efforts to reduce the application of the insecticide Btk in close
proximity to sites occupied by the island marble butterfly. The final
decision over the use of insecticide for control of invasive moths and
butterflies has been, and will continue to be, made by the Washington
State Department of Agriculture after coordination with the Service and
WDFW. All pesticide used by the State of Washington is applied in
compliance with label instructions, which are designed to reduce
overspray, drift, and other negative impacts to nontarget organisms and
areas.
Summary of Other Natural or Manmade Factors Affecting Its Continued
Existence
The small population size of the island marble butterfly makes the
species highly vulnerable to stochastic events (such as storm surges
and climate anomalies) that directly or indirectly affect survival and
reproductive success or the extent of habitat. Storm surges, which can
cause direct mortality of island marble butterflies and habitat loss,
are likely to increase with climate change. Although successful
captive-rearing and release of island marble butterflies is an
important achievement that has supplemented numbers at American Camp
since 2013, threats to the species and its habitat continue. The range
of the island marble butterfly has continued to contract at American
Camp, and the number of island marble butterflies observed annually has
continued to decline. These conservation efforts will need to be
continued into the future and be monitored to assess their long-term
conservation value to the island marble butterfly before we can
determine their efficacy.
Cumulative Effects
In our analysis of the five factors, we found that the island
marble butterfly is likely to be affected by loss and degradation of
habitat, direct and incidental predation, and vulnerabilities
associated with small population size. Multiple stressors acting in
combination have greater potential to affect the island marble
butterfly than each factor alone. For example, increased sea level
resulting from climate change may enhance the impacts of storm surges
and flooding on low-lying coastal habitat where the one native larval
host plant for the species occurs. The combined effects of
environmental and demographic stochasticity, especially on a small
population, can lead to a decline that is unrecoverable and results in
extinction (Brook et al. 2008, pp. 457-458). The impacts of the
stressors described above, which might be sustained by a larger, more
resilient population, have the potential in combination to rapidly
affect the size, growth rate, and genetic integrity of a species that
persists as a small, isolated population. Thus, factors that, by
themselves, may not have a significant effect on the island marble
butterfly, may affect the species when considered in combination.
Determination of Island Marble Butterfly
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of ``endangered species'' or
``threatened species.'' The Act defines an ``endangered species'' as a
species that is ``in danger of extinction throughout all or a
significant portion of its range,'' and a ``threatened species'' as a
species that is ``likely to become an endangered species within the
foreseeable future throughout all or a significant portion of its
range.'' The Act requires that we determine whether a species meets the
definition of ``endangered species'' or ``threatened species'' because
of any of the following factors: (A) The present or threatened
destruction, modification, or curtailment of its habitat or range; (B)
Overutilization for commercial, recreational, scientific, or
educational purposes; (C) Disease or predation; (D) The inadequacy of
existing regulatory mechanisms; or (E) Other natural or manmade factors
affecting its continued existence.
Status Throughout All of Its Range
As required by the Act, we have carefully assessed the best
scientific and commercial information available regarding the past,
present, and future threats to the island marble butterfly. Since the
species was discovered in the San Juan Islands in 1998, the species'
range has contracted from five populations on two islands (San Juan and
Lopez) to a single population, at American Camp on San Juan Island,
today. The causes of these extirpations are not well understood, but
likely include habitat loss outside American Camp from a combination of
sources. Within the single remaining population at American Camp, the
number of sites where island marble butterflies are detected during
surveys declined from 25 in 2007, to 4 in 2015. Encounter rates for
adult butterflies calculated from survey data have declined each year,
from almost 2 per 100 meters in 2004, to about 0.3 per 100 meters in
2015. The slight increase in this rate in 2016, to 0.6 per 100 meters,
does not reverse the overall trend of decline. Captive rearing and
release of the island marble butterfly shows promise for bolstering the
remaining population of the species. However, the potential for this
species to recolonize areas within its historical range is uncertain
due to ongoing, pervasive habitat degradation that results from
herbivory by deer and other animals on larval host plants, from plant
succession and invasion by nonnative plants that render habitat
unsuitable for larval host plants, and potentially from cultivation and
other land uses. The widespread occurrence of native (spiders) and
nonnative (wasps) predators of eggs and larvae is also an ongoing
threat that may hamper or prevent potential recolonizations.
Furthermore, the source for any recolonizations consists of a single,
small population already vulnerable to these threats and to stochastic
sources of mortality, such as severe storms and other climate
anomalies.
In summary, we have identified the following threats to the island
marble butterfly: (1) Habitat loss and degradation from plant
succession and competition with invasive species that displace larval
host plants; herbivory by deer, European rabbits, and brown garden
snails; and storm surges (Factor A); (2) direct predation by spiders
and wasps, and incidental predation by deer (Factor C); (3) small
population size and vulnerability to stochastic events (Factor E); and
(4) the cumulative effects of small population size and the restricted
range combined with any stressor that removes individuals from the
population or decreases the species' reproductive success (Factor E).
These threats affect the island marble butterfly
[[Page 26806]]
throughout the entirety of its range and are ongoing and likely to
persist into the foreseeable future. These factors pose threats to the
island marble butterfly whether considered individually or
cumulatively. The existing regulatory mechanisms (Factor D) and ongoing
conservation efforts are not currently sufficient to ameliorate the
impact of these threats; despite intense focused efforts to conserve
the species, population numbers continue to decline.
The ongoing threats of habitat loss and degradation, predation, the
effects of small population size, and stochastic events that cause
mortality or reduce reproductive success render this species in its
entirety presently in danger of extinction throughout all of its range.
The Act defines an endangered species as any species that is ``in
danger of extinction throughout all or a significant portion of its
range'' and a threatened species as any species ``that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range.'' The ongoing threats of
habitat loss and degradation, predation, the effects of small
population size, and stochastic events that cause mortality or reduce
reproductive success render this species in its entirety presently in
danger of extinction. Therefore, on the basis of the best available
scientific and commercial information, we are listing the island marble
butterfly as endangered in accordance with sections 3(6) and 4(a)(1) of
the Act. We find that threatened species status is not appropriate for
the island marble butterfly because of its already contracted range and
single remaining population, because the threats are ongoing and
affecting the entirety of the species, and because these threats are
expected to continue into the future.
Status Throughout a Significant Portion of Its Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. We have determined that the island marble butterfly is in
danger of extinction throughout all of its range, and accordingly, did
not undertake an analysis of any significant portion of its range.
Because we have determined that the island marble butterfly warrants
listing as endangered throughout all of its range, our determination is
consistent with the decision in Center for Biological Diversity v.
Everson, 2020 WL 437289 (D.D.C. Jan. 28, 2020), in which the court
vacated the aspect of the 2014 Significant Portion of its Range Policy
that provided the Services do not undertake an analysis of significant
portions of a species' range if the species warrants listing as
threatened throughout all of its range.
Determination of Status
Our review of the best available scientific and commercial
information indicates that the island marble butterfly meets the
definition of an endangered species. Therefore, we are listing the
island marble butterfly as an endangered species in accordance with
sections 3(6) and 4(a)(1) of the Act.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
practices. Recognition through listing results in public awareness, and
conservation by Federal, State, Tribal, and local agencies, private
organizations, and individuals. The Act encourages cooperation with the
States and requires that recovery actions be carried out for all listed
species. The protection required by Federal agencies and the
prohibitions against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Subsection 4(f) of the Act requires the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The recovery planning process involves the
identification of actions that are necessary to halt or reverse the
species' decline by addressing the threats to its survival and
recovery. The goal of this process is to restore listed species to a
point where they are secure, self-sustaining, and functioning
components of their ecosystems.
Recovery planning includes the development of a recovery outline
shortly after a species is listed and preparation of a draft and final
recovery plan. The recovery outline guides the immediate implementation
of urgent recovery actions and describes the process to be used to
develop a recovery plan. Revisions of the plan may be done to address
continuing or new threats to the species, as new substantive
information becomes available. The recovery plan identifies site-
specific management actions that set a trigger for review of the five
factors that control whether a species remains endangered or may be
reclassified from endangered to threatened (``downlisted'') or removed
from listed status (``delisted''), and methods for monitoring recovery
progress. Recovery plans also establish a framework for agencies to
coordinate their recovery efforts and provide estimates of the cost of
implementing recovery tasks. Recovery teams (composed of species
experts, Federal and State agencies, nongovernmental organizations, and
stakeholders) are often established to develop recovery plans. When
completed, the recovery outline, draft recovery plan, and the final
recovery plan will be available on our website (https://www.fws.gov/endangered) or from our Washington Fish and Wildlife Office (see FOR
FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
Following publication of this final rule, funding for recovery
actions will be available from a variety of sources, including Federal
budgets, State programs, and cost share grants for non-Federal
landowners, the academic community, and nongovernmental organizations.
In addition, pursuant to section 6 of the Act, the State of Washington
will be eligible for Federal funds to implement management actions that
promote the protection or recovery of the island marble butterfly.
Information on our grant programs that are available to aid species
recovery can be found at: https://www.fws.gov/grants.
Please let us know if you are interested in participating in
recovery efforts for the island marble butterfly. Additionally, we
invite you to submit any new information on this species whenever it
becomes available and any information you may have for recovery
planning purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their
[[Page 26807]]
actions with respect to any species that is listed as an endangered or
threatened species and with respect to its critical habitat, if any is
designated. Regulations implementing this interagency cooperation
provision of the Act are codified at 50 CFR part 402. Section 7(a)(2)
of the Act requires Federal agencies to ensure that activities they
authorize, fund, or carry out are not likely to jeopardize the
continued existence of any endangered or threatened species or destroy
or adversely modify its critical habitat. If a Federal action may
affect a listed species or its critical habitat, the responsible
Federal agency must enter into consultation with the Service.
Federal agency actions within the species' habitat that may require
conference or consultation or both as described in the preceding
paragraph include management and any other landscape-altering
activities on Federal lands administered by the Bureau of Land
Management, Farm Service Agency, Federal Highway Administration,
National Park Service, U.S Army Corps of Engineers, U.S. Fish and
Wildlife Service, U.S. Department of Agriculture, and the U.S. Coast
Guard.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to endangered wildlife.
The prohibitions of section 9(a)(1) of the Act, codified at 50 CFR
17.21, make it illegal for any person subject to the jurisdiction of
the United States to take (which includes harass, harm, pursue, hunt,
shoot, wound, kill, trap, capture, or collect; or to attempt any of
these) endangered wildlife within the United States or on the high
seas. In addition, it is unlawful to import; export; deliver, receive,
carry, transport, or ship in interstate or foreign commerce in the
course of commercial activity; or sell or offer for sale in interstate
or foreign commerce any listed species. It is also illegal to possess,
sell, deliver, carry, transport, or ship any such wildlife that has
been taken illegally. Certain exceptions apply to employees of the
Service, the National Marine Fisheries Service, other Federal land
management agencies, and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits are codified at 50 CFR 17.22. With regard to
endangered wildlife, a permit may be issued for the following purposes:
For scientific purposes, to enhance the propagation or survival of the
species, and for incidental take in connection with otherwise lawful
activities. There are also certain statutory exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a final listing
on proposed and ongoing activities within the range of a listed
species. Due to the cryptic nature of this species throughout a large
portion of the year, we are unable, at this time, to identify specific
activities within the known range of the species that wouldnot result
in unauthorized take under section 9 of the Act.
Based on the best available information, the following activities
may potentially result in a violation of section 9 the Act; this list
is not comprehensive:
(1) Unauthorized collecting, handling, possessing, selling,
delivering, carrying, or transporting of island marble butterflies,
including import or export across State lines and international
boundaries, except for properly documented antique specimens at least
100 years old, as defined by section 10(h)(1) of the Act;
(2) Introduction of nonnative species that compete with or prey
upon the island marble butterfly or its host and nectar plants--for
example, the introduction of competing, nonnative plants or animals to
the State of Washington, and in particular the San Juan Islands;
(3) The unauthorized release of biological control agents that
attack any life stage of the island marble butterfly--for example, Btk
release in the range of the species;
(4) Unauthorized modification of the soil profiles or the
vegetation components on sites known to be occupied by island marble
butterflies; or
(5) Intentional disturbance of butterflies (or any life stage
thereof), especially mowing or burning of areas where butterflies are
known to occur during the breeding season.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Washington
Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Critical Habitat
Background
Critical habitat is defined in section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features
(a) Essential to the conservation of the species, and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Our regulations at 50 CFR 424.02 define the geographical area
occupied by the species as an area that may generally be delineated
around species' occurrences, as determined by the Secretary (i.e.,
range). Such areas may include those areas used throughout all or part
of the species' life cycle, even if not used on a regular basis (e.g.,
migratory corridors, seasonal habitats, and habitats used periodically,
but not solely by vagrant individuals).
Conservation, as defined under section 3 of the Act, means to use
and the use of all methods and procedures that are necessary to bring
an endangered or threatened species to the point at which the measures
provided pursuant to the Act are no longer necessary. Such methods and
procedures include, but are not limited to, all activities associated
with scientific resources management such as research, census, law
enforcement, habitat acquisition and maintenance, propagation, live
trapping, and transplantation, and, in the extraordinary case where
population pressures within a given ecosystem cannot be otherwise
relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act
through the requirement that Federal agencies ensure, in consultation
with the Service, that any action they authorize, fund, or carry out is
not likely to result in the destruction or adverse modification of
critical habitat. The designation of critical habitat does not affect
land ownership or establish a refuge, wilderness, reserve, preserve, or
other conservation area. Such designation does not allow the government
or public to access private lands. Such designation does not require
implementation of restoration, recovery, or enhancement measures by
non-Federal landowners. Where a landowner requests Federal agency
funding or authorization for an action that may affect a listed species
or critical habitat,
[[Page 26808]]
the consultation requirements of section 7(a)(2) of the Act would
apply, but even in the event of a destruction or adverse modification
finding, the obligation of the Federal action agency and the landowner
is not to restore or recover the species, but to implement reasonable
and prudent alternatives to avoid destruction or adverse modification
of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographical area occupied by the species at the time
it was listed are included in a critical habitat designation if they
contain physical or biological features (1) which are essential to the
conservation of the species and (2) which may require special
management considerations or protection. For these areas, critical
habitat designations identify, to the extent known using the best
scientific and commercial data available, those physical or biological
features that are essential to the conservation of the species (such as
space, food, cover, and protected habitat). In identifying those
physical or biological features within an area, we focus on the
specific features that support the life-history needs of the species,
including, but not limited to, water characteristics, soil type,
geological features, prey, vegetation, symbiotic species, or other
features. A feature may be a single habitat characteristic, or a more
complex combination of habitat characteristics. Features may include
habitat characteristics that support ephemeral or dynamic habitat
conditions. Features may also be expressed in terms relating to
principles of conservation biology, such as patch size, distribution
distances, and connectivity.
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographical
area occupied by the species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species. For example, an area currently occupied by the species but
that was not occupied at the time of listing may be essential to the
conservation of the species and may be included in the critical habitat
designation.
Section 4 of the Act requires that we designate critical habitat on
the basis of the best scientific data available. Further, our Policy on
Information Standards Under the Endangered Species Act (published in
the Federal Register on July 1, 1994 (59 FR 34271)), the Information
Quality Act (section 515 of the Treasury and General Government
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)),
and our associated Information Quality Guidelines provide criteria,
establish procedures, and provide guidance to ensure that our decisions
are based on the best scientific data available. They require our
biologists, to the extent consistent with the Act and with the use of
the best scientific data available, to use primary and original sources
of information as the basis for recommendations to designate critical
habitat.
When we are determining which areas should be designated as
critical habitat, our primary source of information is generally the
information from the species status assessment (SSA) document and
information developed during the listing process for the species.
Additional information sources may include any generalized conservation
strategy, criteria, or outline that may have been developed for the
species; the recovery plan for the species; articles in peer-reviewed
journals; conservation plans developed by States and counties;
scientific status surveys and studies; biological assessments; other
unpublished materials; or experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another
over time. We recognize that critical habitat designated at a
particular point in time may not include all of the habitat areas that
we may later determine are necessary for the recovery of the species.
For these reasons, a critical habitat designation does not signal that
habitat outside the designated area is unimportant or may not be needed
for recovery of the species. Areas that are important to the
conservation of the species, both inside and outside the critical
habitat designation, will continue to be subject to: (1) Conservation
actions implemented under section 7(a)(1) of the Act; (2) regulatory
protections afforded by the requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their actions are not likely to
jeopardize the continued existence of any endangered or threatened
species; and (3) section 9 of the Act's prohibitions on taking any
individual of the species, including taking caused by actions that
affect habitat. Federally funded or permitted projects affecting listed
species outside their designated critical habitat areas may still
result in jeopardy findings in some cases. These protections and
conservation tools will continue to contribute to recovery of this
species. Similarly, critical habitat designations made on the basis of
the best available information at the time of designation will not
control the direction and substance of future recovery plans, habitat
conservation plans (HCPs), or other species conservation planning
efforts if new information available at the time of these planning
efforts calls for a different outcome.
On August 27, 2019, we published a final rule in the Federal
Register (84 FR 45020) to revise our regulations concerning the
procedures and criteria used for listing or removing species from the
Lists of Endangered and Threatened Wildlife and Plants and designating
critical habitat. That rule became effective on September 26, 2019, but
as stated in that rule, the revisions it sets forth apply to
classification and critical habitat rules for which a proposed rule was
published after September 26, 2019. Since the proposed rule for the
Island marble butterfly critical habitat was published on April 12,
2018 (83 FR 15900), this final rule follows the version of Sec. 424.12
that was in effect prior to September 26, 2019.
Physical or Biological Features
In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12(b), in determining which areas within the geographical
area occupied by the species at the time of listing to designate as
critical habitat, we consider the physical or biological features that
are essential to the conservation of the species and which may require
special management considerations or protection. For example, physical
features might include gravel of a particular size required for
spawning, alkali soil for seed germination, protective cover for
migration, or susceptibility to flooding or fire that maintains
necessary early-successional habitat characteristics. Biological
features might include prey species, forage grasses, specific kinds or
ages of trees for roosting or nesting, symbiotic fungi, or a particular
level of nonnative species consistent with conservation needs of the
listed species. The features may also be combinations of habitat
characteristics and may encompass the relationship between
characteristics or the necessary amount of a characteristic needed to
support the life history of the species. In considering whether
features are essential to the conservation of the species, the Service
may consider an appropriate quality, quantity, and spatial and temporal
arrangement of habitat characteristics in the context of the life-
history needs, condition, and status of the species. These
characteristics include, but are not limited to, space for individual
and population growth and for normal behavior; food, water, air, light,
minerals, or other nutritional or
[[Page 26809]]
physiological requirements; cover or shelter; sites for breeding,
reproduction, or rearing (or development) of offspring; and habitats
that are protected from disturbance.
We derive the specific physical or biological features essential to
the conservation of the island marble butterfly from studies of this
species' habitat, ecology, and life history as described below. We have
determined that the following physical or biological features are
essential to the conservation of the island marble butterfly:
Space for Individual and Population Growth and for Normal Behavior
The island marble butterfly has previously been documented as
having as many as five core populations across San Juan and Lopez
Islands in the San Juan archipelago, but of those five, there is only
one location where it has been consistently detected on an annual basis
since its rediscovery in 1998 at American Camp, part of San Juan Island
National Historical Park. The long-term occupancy of American Camp
indicates that one or more aspects of this site provide the combination
of habitat factors needed by the species. American Camp encompasses
multiple small populations within large expanses of diverse habitat,
including open south-facing slopes, varied broad-scale topographic
features, and low-statured plant communities (Lambert 2011, pp. 151-
152; Lambert 2016a, p. 4). Surface topography (slope and aspect) and
landscape features that have topographic relief (slopes, bluffs, sand
banks, or driftwood berms) are critical to the movement and dispersal
of the island marble butterfly (Lambert 2011, p. 152).
The portion of the park where the island marble butterfly persists
contains an open expanse of prairie and dune habitat greater than 700
ac (283 ha) and is bounded on two sides by marine shoreline. The island
marble butterfly uses landscape features to fly low across the land,
following shallow ridgelines associated with sand dunes, road cuts, and
coastal bluffs. We surmise that island marble butterflies use the lee
of rolling hills or hollows in broader expanses of prairie and dune
habitats to facilitate their movements. Therefore, we determine habitat
areas large enough to include broad topographic features (e.g.,
ridgelines, hills, and bluffs) to be physical or biological features
for the island marble butterfly.
At a rangewide scale, the island marble butterfly exhibits
metapopulation dynamics, while on a local scale, ``patchy'' population
dynamics best describes the movement of individuals between suitable
habitat patches (Lambert 2011, pp. 147-148). Specifically, the island
marble butterfly tends to occupy multiple habitat patches within a
larger, heterogeneous area, with some small amount of movement between
suitable habitat patches. Individual butterflies rarely move distances
greater than 0.4 mi (600 m) (Peterson 2010, p. 3). Marked individuals
are nearly always recaptured at the sites where they were marked, with
a single exception when a marked individual was recaptured 1.2 mi (1.9
km) from its site of origin (Peterson 2010, p. 3). Within the last
known occupied site, smaller occupied patches have been observed to
undergo local extirpation events, but the close proximity of nearby
populations within the larger contiguous area has allowed for
recolonization (Lambert 2011, p. 155). Areas large enough to contain
multiple small populations of island marble butterfly that allow for
population connectivity and re-establishment are essential to the
conservation of the species. Therefore, we conclude that areas large
enough to support multiple small populations of the species are a
physical or biological feature essential to the island marble
butterfly.
Island marble butterflies tend to fly close to the ground, along
the edges of treed areas or along marine shorelines. Therefore, forest
and open water create natural barriers to movement (Lambert 2011, pp.
49, 50). Male island marble butterflies fly low (approximately 5 ft
(1.5 m) above the ground) and follow ridgelines, bluffs, road-cuts,
trail edges, fence lines, and shrub or forest edges in search of mates
(Lambert 2011, pp. 47-48). Female island marble butterflies have been
observed to fly in low (approximately 3 ft (1 m) above the ground),
wide (330-980 ft (100-500 m)) circles above the ground searching for
suitable host plants upon which to lay their eggs (Lambert 2011, p.
49). We conclude that large open areas with few trees are a physical or
biological feature for the island marble butterfly.
Based on the best information available, we estimate that the
conservation of the island marble butterfly is best supported by open,
primarily treeless areas with short-statured forb- and grass-dominated
vegetation. Areas should be large enough to allow for the inclusion of
diverse topographic features and habitat types, including sites for
mating, egg laying, feeding, refugia (places to safely harbor), and
diapause locations, and should support multiple discrete occupied
habitat patches, which increases the likelihood of recolonization if
local extinction takes place. Therefore, we conclude that open,
primarily treeless habitat areas that are large enough to support
multiple, small populations and that include broad topographic features
such as ridgelines, hills, and bluffs are physical or biological
features essential to the conservation of the island marble butterfly.
Food, Water, Air, Light, Minerals, or Other Nutritional or
Physiological Requirements
The island marble butterfly needs larval and adult food resources
in order to complete its life cycle: larval host plants (food plants
required by the immature stages of the butterfly) and nectar plants for
the adults. The island marble butterfly has three known larval host
plants, all in the mustard family (Brassicaceae). One is native,
Menzies' pepperweed, and two are nonnative, field mustard and tumble
mustard (Miskelly 2004, pp. 33, 38; Lambert 2011, p. 2). These three
larval host plants are essential components of habitat for the island
marble butterfly.
All three larval host plants occur in open grass- and forb-
dominated plant communities, but each species is most robust in one of
three specific habitat types, with little overlap: Menzies' pepperweed
at the edge of low-lying coastal lagoon habitat; field mustard in
upland prairie habitat, disturbed fields, and disturbed soils,
including soil piles from construction; and tumble mustard in sand dune
habitat (Miskelly 2004, p. 33; Miskelly and Potter 2009, p. 9; Lambert
2011, pp. 24, 121-123). While each larval host plant can occur in each
of the three habitat types referenced above, female island marble
butterflies typically lay eggs on only the most robust host plants in
each aforementioned habitat type (Miskelly 2004, p. 33; Lambert 2011,
pp. 24, 41, 50, 55-57, 121-123).
We conclude that the presence of Menzies' pepperweed, field
mustard, or tumble mustard is a physical or biological feature upon
which the island marble butterfly depends.
Adults primarily forage for nectar on their larval host plants
(Potter 2015e, pers. comm.). They also use a variety of other nectar
plants that flower during the island marble butterfly's flight period,
which is generally from mid-April to mid- to late-June. Adults have
been observed to nectar on yellow sand verbena, yarrow, small-flowered
fiddleneck, American sea rocket, field chickweed, common stork's bill,
dovefoot geranium, hairy cat's ear, common lomatium, seashore lupine,
common forget-me-not, California
[[Page 26810]]
buttercup, trailing blackberry, dandelion, death camas, and Howell's
brodiaea (Miskelly 2004, p. 33; Pyle 2004, pp. 23-26, 33; Miskelly and
Potter 2005, p. 6; Lambert 2011, p. 120; Vernon and Weaver 2012,
appendix 12; Lambert 2015a, p. 2; Lambert 2015b, in litt.). Of these
additional nectar resources, island marble butterflies are most
frequently observed feeding on yellow sand verbena, small-flowered
fiddleneck, and field chickweed (Potter 2015e, pers. comm.). We
conclude that adult nectar resources, including, but not limited to,
those listed here, are a physical or biological feature upon which the
island marble butterfly depends.
Like many animals that rely on external sources of body heat
(ectotherms), the island marble butterfly is more active at warmer
temperatures; for this species, this generally means temperatures that
are higher than 55 degrees Fahrenheit ([deg]F) (13 degrees Celsius
([deg]C)). This leads to adult (winged) island marble butterflies being
most active between the hours of 10 a.m. and 4 p.m. The island marble
butterfly relies upon solar radiation for the warmth that drives their
development, mate-finding, and reproduction. We conclude that exposure
to the sun provided by open, primarily treeless areas with some south-
facing slopes and short-statured vegetation is a physical or biological
feature upon which the island marble butterfly depends.
We consider open sunlit areas containing at least one species of
larval host plant, Menzies' pepperweed, field mustard, and/or tumble
mustard, with both flower buds and blooms between the months of May
through July to be physical or biological features of island marble
butterfly habitat. We additionally consider the presence of adult
nectar plants in flower to be a physical or biological feature of
island marble butterfly habitat.
Sites for Breeding, Reproduction, or Rearing (or Development) of
Offspring
Male island marble butterflies are attracted to white and may
investigate white picket fences, white lines on surface roads, or other
white objects while searching for a mate (Lambert 2011, p. 47). The
island marble butterfly primarily uses short-statured, white-flowering
plants such as field chickweed as sites for mate attraction and mating
(Lambert 2014b, p. 17). We conclude that the presence of short-
statured, white-flowering plants during the flight period (generally
from mid-April to mid- to late-June) for the island marble butterfly to
be a physical or biological feature of the island marble butterfly
habitat.
Once mated, gravid female island marble butterflies seek out larval
host plants at an optimal growth stage for egg laying (recently hatched
caterpillars require tender plant parts, such as immature flower buds,
because their mouthparts are not developed enough to eat hardened plant
matter) (Lambert 2011, pp. 9-10). Larval host plant flowering phenology
(timing of flower opening) is important for island marble butterflies.
If the plants emerge too early, there may not be enough tissue at the
right stage available for the larvae to go through their developmental
phases. If the plants emerge too late, female butterflies may not
recognize the larval host plants as suitable sites to lay eggs.
Female island marble butterflies carefully gauge the suitability of
each larval host plant, preferentially selecting plants that possess
both flowers and buds to lay eggs on. Plants with greater than 50
percent of their flowers in bloom are more likely to be selected than
plants in an earlier (less than 50 percent of flowers in bloom) or
later developmental stage (Lambert 2011, pp. 59-60). Female island
marble butterflies tend to lay eggs singly on the immature buds of the
flowers of their larval host plants, rarely laying eggs on
inflorescences that are already occupied by island marble butterfly
eggs or larvae (Lambert 2011, pp. 51-57). Female island marble
butterflies prefer larval host plants growing in low-density patches
with less than one plant per meter square and tend to choose plants
that are along the outer edge of a patch of larval host plants rather
than in areas with a high density of host plants (Lambert 2011, pp. 53,
68-69; Lambert 2015d, p. 9). Additionally, host plant phenology (timing
of development) plays a significant role in determining where females
lay eggs. Low- to medium-density larval host plants, with both flower
buds and blooms on them between the months of May through July, for
egg-laying and larval development are a physical or biological feature
of island marble butterfly habitat.
After hatching, larvae of the island marble butterfly rapidly
progress through five instars (larval growth stages) and have been
documented to then move up to 13 ft (4 m) from their larval host plant
to nearby standing vegetation (usually tall grasses) to pupate (Lambert
2011, p. 19). Island marble butterfly larvae use nearby vegetation as
bridges to other plants and appear to avoid being close to the ground
while searching for a safe site on which to form a chrysalis (pupal
casing) (Lambert 2011, pp. 20-21). Therefore, we find that the presence
of larval host plants, in complement with tall, standing vegetation
that provides the structure necessary to allow mature larvae to cross
to a safe pupation site, is a physical or biological feature of island
marble butterfly habitat.
Habitats That Are Protected From Disturbance or Are Representative of
the Historical, Geographical, and Ecological Distributions of a Species
The island marble butterfly spends approximately 300 days in
diapause (a form of dormancy) as a chrysalis (pupa) before undergoing
metamorphosis to emerge as a winged adult the following spring. Unlike
other butterfly species that may diapause underground or,
alternatively, rapidly advance from egg to winged adult and overwinter
in an adult phase, the island marble butterfly enters diapause
aboveground and very close to where it hatched. During diapause, the
island marble butterfly is vulnerable to any activity such as
trampling, mowing, harvesting, grazing, or plowing that may disturb or
destroy the vegetative structure to which a larva has attached its
pupal casing. The larval host plants for the island marble butterfly
are annual (or biennial), and habitat patches for the island marble
butterfly do not tend to persist in the same area continuously over
time. Leaving the vegetation near where larval host plants established
in the spring until mid-summer the following year provides a safe place
for the island marble butterfly chrysalids to harbor until they emerge.
Therefore, we find that sufficient areas of undisturbed vegetation
surrounding larval host plants that are left standing for a sufficient
period of time in order for the island marble butterfly to complete its
life cycle is a physical or biological feature of island marble
butterfly habitat.
Summary of Essential Physical or Biological Features
We have determined that the following physical or biological
features of the areas on San Juan Island, Washington, that are
essential to the conservation of the island marble butterfly are:
(a) Open, primarily treeless areas with short-statured forb- and
grass-dominated vegetation that include diverse topographic features
such as ridgelines, hills, and bluffs for patrolling, dispersal
corridors between habitat patches, and some south-facing terrain. Areas
must be large enough to allow for the development of patchy-population
[[Page 26811]]
dynamics, allowing for multiple small populations to establish within
the area.
(b) Low- to medium-density larval host plants, with both flower
buds and blooms on them between the months of May through July, for
egg-laying and larval development. Larval host plants may be any of the
following: Brassica rapa, Sisymbrium altissimum, or Lepidium
virginicum.
(c) Adult nectar resources in flower and short-statured, white-
flowering plants in bloom used for mate-finding, which may include, but
are not limited to, Abronia latifolia (yellow sand verbena), Achillea
millefolium (yarrow), Amsinckia menziesii (small-flowered fiddleneck),
Cakile edentula (American sea rocket), Cerastium arvense (field
chickweed), Erodium cicutarium (common stork's bill), Geranium molle
(dovefoot geranium), Hypochaeris radicata (hairy cat's ear), Lomatium
utriculatum (common lomatium), Lupinus littoralis (seashore lupine),
Myosotis discolor (common forget-me-not), Ranunculus californicus
(California buttercup), Rubus ursinus (trailing blackberry), Taraxacum
officinale (dandelion), Toxicoscordion venenosum (death camas, formerly
known as Zigadenus venenosus), and Triteleia grandiflora (Howell's
brodiaea, formerly Brodiaea howellii).
(d) Areas of undisturbed vegetation surrounding larval host plants
sufficient to provide secure sites for diapause and pupation. The
vegetation surrounding larval host plants must be left standing for a
sufficient period of time for the island marble butterfly to complete
its life cycle.
Special Management Considerations or Protection
When designating critical habitat, we assess whether the specific
areas within the geographical area occupied by the species at the time
of listing contain features that are essential to the conservation of
the species and which may require special management considerations or
protection. Because the island marble butterfly depends on vegetation
that requires disturbance and open areas to establish, special
management may be necessary to both maintain low-level disturbance and
to prevent the invasion of weedy native and nonnative plant species,
such as Douglas fir, Mediterranean pasture grasses, and thistle.
Beneficial special management activities could include prescribed
burning to remove standing vegetation and seedlings and to reduce seed
set of nonnative plant species. Additionally, the application of
selective herbicides to combat specific invasive plants may also prove
useful in vegetation management. For some weedy species, hand-pulling
can be an effective vegetation management tool, if staffing and
resources allow.
Special management considerations within the critical habitat unit
may include protection of larval host plants from herbivory by browsing
deer, European rabbits, and brown garden snails. These herbivores
constitute the primary threat to the larval host plants upon which the
island marble butterfly depends. Special management actions that could
ameliorate the threat of herbivory by deer, European rabbits, and brown
garden snails could include lethal control methods, such as targeted
hunting or professional removal. For deer, exclusion fencing increases
the survivorship of both larval host plants and the island marble
butterfly in the fenced areas, but the fences are difficult to erect
and maintain and provide a host of other challenges for the land
management agencies. Additionally, exclusion fencing does nothing to
reduce the number of deer, which is the primary cause of the intense
browsing pressure on the larval host plants for the island marble
butterfly (Lambert 2011, pp. 85-104, 127; Lambert 2014a, p. 3; Lambert
2015d, pp. 14-18). Fencing is not effective against European rabbits
and brown garden snails.
Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act, we use the best
scientific data available to designate critical habitat. In accordance
with the Act and our implementing regulations at 50 CFR 424.12(b), we
review available information pertaining to the habitat requirements of
the species and identify specific areas within the geographical area
occupied by the species at the time of listing and any specific areas
outside the geographical area occupied by the species to be considered
for designation as critical habitat. In this case, we are not
designating any areas outside the geographical area occupied by the
species.
When we are determining which areas should be designated as
critical habitat, our primary source of information is generally the
information developed during the listing process for the species.
Additional information sources may include the recovery plan for the
species, articles in peer-reviewed journals, conservation plans
developed by States and counties, scientific status surveys and
studies, biological assessments, other unpublished materials, or
experts' opinions or personal knowledge. In this case, we used existing
occurrence data for the island marble butterfly and information on the
habitat and ecosystems upon which it depends. These sources of
information included, but were not limited to:
(1) Data used to prepare the rule to list the species;
(2) Information from biological surveys;
(3) Various agency reports and databases;
(4) Information from NPS and other cooperators;
(5) Information from species experts;
(6) Data and information presented in academic research theses; and
(7) Regional Geographic Information System (GIS) data (such as
species occurrence data, land use, topography, aerial imagery, soil
data, and land ownership maps) for area calculations and mapping.
Areas Occupied at the Time of Listing
In accordance with the Act and our implementing regulations at 50
CFR 424.12(b), we reviewed available information pertaining to the
habitat requirements of the species, identified specific areas within
the geographical area occupied by the species at the time of listing,
and examined whether we could identify any specific areas outside the
geographical area occupied by the species to be considered for
designation as critical habitat. In this case, as we are listing the
island marble butterfly concurrently with the designation of critical
habitat, all areas presently occupied by the island marble butterfly
constitute those areas occupied at the time of listing.
We plotted the known locations of the island marble butterfly where
they occur in Washington using 2015 National Agriculture Imagery
Program (NAIP) digital imagery in ArcGIS, version 10.4 (Environmental
Systems Research Institute, Inc.), a computer geographic information
system program, and determined that the currently occupied areas
contain the physical or biological features needing special management,
as discussed above. We also analyzed the appropriate quantity and
spatial arrangement of these features in the context of the life
history, status, and conservation needs of the species.
We note that limitations in available GIS data and the scale of
designations can affect our precision in mapping critical habitat
boundaries. We strive to use clearly recognizable geographic or legal
features in designating critical habitat boundaries; however, in those
instances where we think critical habitat maps may cause uncertainty
over the precise extent of mapped critical
[[Page 26812]]
habitat, we have attempted to clarify with supplemental narrative
descriptions.
Survey effort for the island marble butterfly has not been
consistent spatially or temporally. Island-wide surveys of San Juan and
Lopez Islands were discontinued by WDFW in 2012, due to decreased
detections and the lack of larval host plants in previously occupied
areas across both islands. In 2015, the Service funded an island-wide
survey of San Juan, and no occurrences were documented outside of the
known occupied area centered on American Camp at the southern end of
San Juan Island. The last survey of Lopez Island was conducted in 2012,
and a single larva was observed. There have been no reports of island
marble butterflies from Lopez Island since 2012.
Therefore, the Service considers areas to be occupied at the time
of listing if there are occurrence records within those areas within
the last 5 years, or if areas adjacent to known occupied areas have the
physical or biological features upon which the island marble butterfly
depends and there are no barriers to dispersal. It is reasonable to
conclude that the species regularly occurs in such areas because of the
species' population dynamics and frequent movement between habitat
patches, as discussed above. Occurrence records are deemed credible if
recorded by a Federal, State, or contract biologist, or a qualified
surveyor for the island marble butterfly.
We have also determined that all of these occupied areas (areas
with documented occurrences as well as adjacent areas containing
suitable habitat and where there are no barriers to dispersal) contain
one or more of the essential physical or biological features. For these
reasons and due to the restricted range of the island marble butterfly,
we determined that all known occupied areas should be designated as
critical habitat. The only known occupied area is centered on American
Camp at San Juan Island National Historical Park and includes adjacent
lands to the east and west of the National Park that are owned and/or
managed by BLM, WDNR, San Juan County, Washington State Parks and
Recreation, and private individuals.
The critical habitat designated on the private parcels along Eagle
Cove only includes the area of steep coastal bluff between the marine
shoreline and the upland edge at the top of the bluff. It does not
include areas landward of the top of the bluff, which are typically
mowed and maintained as yard.
When determining critical habitat boundaries within this final
rule, we made every effort to avoid including developed areas such as
lands covered by buildings, pavement, and other structures because such
lands lack physical or biological features for the island marble
butterfly. The scale of the maps we prepared under the parameters for
publication within the Code of Federal Regulations may not reflect the
exclusion of such developed lands. Any such lands inadvertently left
inside critical habitat boundaries shown on the maps of this final rule
have been excluded by text in the rule and are not designated as
critical habitat. Therefore, a Federal action involving these lands
will not trigger section 7 consultation with respect to critical
habitat and the requirement of no adverse modification unless the
specific action would affect the physical or biological features in the
adjacent critical habitat. Please note that we specifically include
road margins and shoulders in the critical habitat designation, as the
island marble butterfly larval host plants often establish in these
disturbed areas and may be used by the island marble butterfly for egg-
laying and development. Special management considerations for road
margins and shoulders may apply.
We are not designating any areas as critical habitat outside the
geographical area occupied by the species at the time of listing. While
we know the conservation of the species will depend on increasing the
number and distribution of populations of the island marble butterfly,
not all of its historical range will be essential to the conservation
of the species, and we are unable to delineate any specific unoccupied
areas that are essential at this time. Sites both within and outside of
the central valleys of San Juan and Lopez Islands were previously
occupied by the island marble butterfly. A number of areas within and
outside of these valleys continue to contain some or could develop many
of the physical and biological features upon which the species depends,
although the best available scientific data indicate all these areas
are currently unoccupied. The areas of the central valleys with the
potential to support the physical and biological features continue to
be important to the overall conservation strategy for the island marble
butterfly. However, due to the ephemeral and patchy nature of island
marble butterfly habitat, only some of these areas within these larger
central valley landscapes will likely be essential to the species'
long-term persistence and conservation because of the ease with which
field mustard recruits and the uncertainty associated with habitat
patch longevity at any one site.
Any specific areas essential to the species' conservation within
these broader landscapes are not currently identifiable due to our
limited understanding regarding the ideal configuration for the
development of future habitat patches to support the island marble
butterfly's persistence, the ideal size and number of these habitat
patches, and how these habitat patches may naturally evolve within and
persist on the landscape. Finally, the specific areas needed for
conservation will depend in part on landowner willingness to restore
and maintain the species' habitat in these areas.
Consequently, the Service is considering proposing the future
establishment of one or more experimental populations (such as, but not
limited to, those provided for under section 10(j) of the Act) within
these broad geographic areas after we list the island marble butterfly
under the Act. Section 10(j) of the Act authorizes the Service, by
rulemaking, to establish new populations of listed species that are
within the species' historical range but outside its current natural
range. If we designate a nonessential population, we can adopt a rule
to minimize restrictions on landowners. Any such rule would, to the
maximum extent practicable, represent an agreement between the Service
and affected landowners and government agencies (50 CFR 17.81(d)).
The critical habitat unit was designated based on one or more of
the elements of physical or biological features being present to
support island marble butterfly life processes. The critical habitat
unit contains all of the identified elements of physical or biological
features and supports multiple life processes. Some segments contain
only some elements of the physical or biological features necessary to
support the island marble butterfly's particular use of that habitat.
The critical habitat designation is defined by the map or maps, as
modified by any accompanying regulatory text, presented at the end of
this document under Regulation Promulgation. We include more detailed
information on the boundaries of the critical habitat designation in
the preamble of this document. We will make the coordinates or plot
points or both on which each map is based available to the public on
https://www.regulations.gov at Docket No. FWS-R1-ES-2016-0145, on our
internet site at https://www.fws.gov/wafwo/, and at the field office
responsible for the designation (see FOR FURTHER INFORMATION CONTACT,
above).
[[Page 26813]]
Final Critical Habitat Designation
We are designating one unit as critical habitat for the island
marble butterfly. The critical habitat area described below constitutes
our best assessment at this time of areas that meet the definition of
critical habitat. Table 1 shows the unit, which is occupied.
Table 1--Designated Critical Habitat for the Island Marble Butterfly
------------------------------------------------------------------------
Size of unit
Critical habitat unit Land ownership by in acres
type (hectares)
------------------------------------------------------------------------
Island marble butterfly critical NPS................. 718 (291)
habitat. BLM................. 19 (8)
DHS................. 5 (2)
WDNR and SJCLB...... 1 (0.4)
WDNR................ 37 (15)
SJCPD............... 30 (12)
Private............. 2 (0.8)
-------------------------------------
Total:........................ .................... 812 (329)
------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. NPS = National Park
Service, BLM = Bureau of Land Management, DHS = Department of Homeland
Security (Coast Guard), WDNR = Washington Department of Fish and
Wildlife, SJCLB = San Juan County Land Bank, SJCPD = San Juan County
Parks Department.
The critical habitat designation consists of 812 ac (329 ha) of
land at the southern end of San Juan Island, with San Juan Island
National Historical Park (NPS) being the largest landholder of 718 ac
(291 ha). The Bureau of Land Management (BLM) owns and manages 19 ac (8
ha), Washington Department of Natural Resources (WDNR) owns and manages
37 ac (15 ha) at Cattle Point, the Department of Homeland Security owns
5 ac (2 ha), WDNR and the San Juan County Land Bank (SJCLB) jointly own
1 ac (0.4 ha), San Juan County Parks Department owns 30 ac (12 ha), and
approximately 2 ac (0.8 ha) is in private ownership. The critical
habitat designation is centered on the American Camp portion of San
Juan Island National Historical Park, which is owned and managed by the
National Park Service, but includes adjacent lands both to the east and
the west of National Park Service lands. Boundaries for the critical
habitat unit follow the open, generally treeless habitat that the
island marble butterfly relies upon during its flight period for mate-
finding, reproduction, feeding, and dispersal.
The entirety of the critical habitat unit is within the
geographical area occupied at the time of listing. The designation
contains all of the physical or biological features required to support
the island marble butterfly. The critical habitat designation is almost
entirely conserved for use by or for the benefit of the public and is
heavily used for recreation, primarily in the form of day hiking on
easy trails. NPS has maintained a conservation agreement for the island
marble butterfly with the Service since 2006, with the most recent
renewal signed in December of 2018. As the largest landholder within
the critical habitat unit, NPS continues to support and participate in
ongoing research integral to the conservation of the island marble
butterfly. BLM, DHS, WDNR, SJCLB, and San Juan County Parks are all
engaged in the conservation of the island marble butterfly and meet
with the Service multiple times annually to coordinate conservation
efforts.
Within the critical habitat designation, all of the current threats
to the island marble butterfly are present. Please see Determination,
above, for a summary of the threats and ``Special Management
Considerations or Protection'' for additional recommendations.
Effects of Critical Habitat Designation
Section 7 Consultation
Section 7(a)(2) of the Act requires Federal agencies, including the
Service, to ensure that any action they fund, authorize, or carry out
is not likely to jeopardize the continued existence of any endangered
species or threatened species or result in the destruction or adverse
modification of designated critical habitat of such species. In
addition, section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any agency action which is likely to
jeopardize the continued existence of any species proposed to be listed
under the Act or result in the destruction or adverse modification of
proposed critical habitat.
We published a final rule with a new definition of destruction or
adverse modification on February 11, 2016 (81 FR 7214). Destruction or
adverse modification means a direct or indirect alteration that
appreciably diminishes the value of critical habitat for the
conservation of a listed species. Such alterations may include, but are
not limited to, those that alter the physical or biological features
essential to the conservation of a species or that preclude or
significantly delay development of such features.
If a Federal action may affect a listed species or its critical
habitat, the responsible Federal agency (action agency) must enter into
consultation with us. Examples of actions that are subject to the
section 7 consultation process are actions on State, tribal, local, or
private lands that require a Federal permit (such as a permit from the
U.S. Army Corps of Engineers under section 404 of the Clean Water Act
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10
of the Act) or that involve some other Federal action (such as funding
from the Federal Highway Administration, Federal Aviation
Administration, or the Federal Emergency Management Agency). Federal
actions not affecting listed species or critical habitat, and actions
on State, tribal, local, or private lands that are not federally funded
or authorized, do not require section 7 consultation.
As a result of section 7 consultation, we document compliance with
the requirements of section 7(a)(2) through our issuance of:
(1) A concurrence letter for Federal actions that may affect, but
are not likely to adversely affect, listed species or critical habitat;
or
(2) A biological opinion for Federal actions that may affect and
are likely to adversely affect, listed species or critical habitat.
When we issue a biological opinion concluding that a project is
likely to jeopardize the continued existence of a listed species and/or
destroy or adversely modify critical habitat, we provide reasonable and
prudent
[[Page 26814]]
alternatives to the project, if any are identifiable, that would avoid
the likelihood of jeopardy and/or destruction or adverse modification
of critical habitat. We define ``reasonable and prudent alternatives''
(at 50 CFR 402.02) as alternative actions identified during
consultation that:
(1) Can be implemented in a manner consistent with the intended
purpose of the action,
(2) Can be implemented consistent with the scope of the Federal
agency's legal authority and jurisdiction,
(3) Are economically and technologically feasible, and
(4) Would, in the Service Director's opinion, avoid the likelihood
of jeopardizing the continued existence of the listed species and/or
avoid the likelihood of destroying or adversely modifying critical
habitat.
Reasonable and prudent alternatives can vary from slight project
modifications to extensive redesign or relocation of the project. Costs
associated with implementing a reasonable and prudent alternative are
similarly variable.
Regulations at 50 CFR 402.16 require Federal agencies to reinitiate
consultation on previously reviewed actions in instances where we have
listed a new species or subsequently designated critical habitat that
may be affected and the Federal agency has retained discretionary
involvement or control over the action (or the agency's discretionary
involvement or control is authorized by law). Consequently, Federal
agencies sometimes may need to request reinitiation of consultation
with us on actions for which formal consultation has been completed, if
those actions with discretionary involvement or control may affect
subsequently listed species or designated critical habitat.
Application of the ``Adverse Modification'' Standard
The key factor related to the adverse modification determination is
whether, with implementation of the Federal action, the affected
critical habitat would continue to serve its intended conservation role
for the species. Activities that may destroy or adversely modify
critical habitat are those that result in a direct or indirect
alteration that appreciably diminishes the value of critical habitat
for the conservation of the island marble butterfly. Such alterations
may include, but are not limited to, those that alter the physical or
biological features essential to the conservation of these species or
that preclude or significantly delay development of such features. As
discussed above, the role of critical habitat is to support physical or
biological features essential to the conservation of a listed species
and provide for the conservation of the species.
Section 4(b)(8) of the Act requires us to briefly evaluate and
describe, in any proposed or final regulation that designates critical
habitat, activities involving a Federal action that may destroy or
adversely modify such habitat, or that may be affected by such
designation.
Activities that may affect critical habitat, when carried out,
funded, or authorized by a Federal agency, should result in
consultation for the island marble butterfly. These activities include,
but are not limited to:
(1) Actions that destroy the habitat within the critical habitat
unit. Such activities could include, but are not limited to, new
infrastructure developments, planting forests in historical prairie, or
large paving projects. These activities could disrupt dispersal, mate
finding, and patchy population dynamics, as well as prevent the
recruitment of future habitat.
(2) Actions that would temporarily or permanently remove host
plants from areas within the critical habitat unit that were otherwise
phenologically and spatially available for use by the species. Such
activities could include, but are not limited to, mowing, burning, or
applying herbicide to host plants leading up to or during the flight
season. These activities could reduce the quantity or distribution of
oviposition sites available to the species.
(3) Actions that would temporarily or permanently remove nectar
resources or plants used for mate finding from areas within the
critical habitat unit that were otherwise phenologically and spatially
available for use by the species. Such activities could include, but
are not limited to, mowing, burning, or applying herbicide to nectar or
mate-finding plants leading up to or during the flight season. These
activities could reduce nectaring opportunities or disrupt mate
finding, both of which could reduce fecundity.
(4) Actions that would physically disturb appropriate areas for
diapause and pupation. Such activities could include, but are not
limited to, mowing, trampling, grazing, or burning between flight
seasons. These activities could also kill island marble butterflies in
diapause as pupae.
Exemptions
Application of Section 4(a)(3) of the Act
Section 4(a)(3)(B)(i) of the Act (16 U.S.C. 1533(a)(3)(B)(i))
provides that: ``The Secretary shall not designate as critical habitat
any lands or other geographical areas owned or controlled by the
Department of Defense, or designated for its use, that are subject to
an integrated natural resources management plan [INRMP] prepared under
section 101 of the Sikes Act (16 U.S.C. 670a), if the Secretary
determines in writing that such plan provides a benefit to the species
for which critical habitat is proposed for designation.'' There are no
Department of Defense (DoD) lands with a completed INRMP within the
final critical habitat designation.
Consideration of Impacts Under Section 4(b)(2) of the Act
Section 4(b)(2) of the Act states that the Secretary shall
designate and make revisions to critical habitat on the basis of the
best available scientific data after taking into consideration the
economic impact, national security impact, and any other relevant
impact of specifying any particular area as critical habitat. The
Secretary may exclude an area from critical habitat if he determines
that the benefits of such exclusion outweigh the benefits of specifying
such area as part of the critical habitat, unless he determines, based
on the best scientific data available, that the failure to designate
such area as critical habitat will result in the extinction of the
species. In making that determination, the statute on its face, as well
as the legislative history are clear that the Secretary has broad
discretion regarding which factor(s) to use and how much weight to give
to any factor.
Consideration of Economic Impacts
Section 4(b)(2) of the Act and its implementing regulations require
that we consider the economic impact that may result from a designation
of critical habitat. In order to consider economic impacts, we prepared
an incremental effects memorandum (IEM) and screening analysis, which,
together with our narrative and interpretation of effects, we consider
our draft economic analysis (DEA) of the proposed critical habitat
designation and related factors. The DEA was made available for public
review and comment concurrently with the April 12, 2018, proposed rule
(Industrial Economics, Incorporated 2017). The DEA addresses probable
economic impacts of the critical habitat designation for island marble
butterfly. No additional information was
[[Page 26815]]
submitted during the comment period that pertained to our consideration
of the probable incremental economic impacts of this critical habitat
designation. Additional information relevant to the probable
incremental economic impacts of critical habitat designation for the
island marble butterfly is summarized below and available in the
screening analysis for the island marble butterfly (Industrial
Economics, Incorporated 2017), available at https://www.regulations.gov.
The critical habitat designation for the island marble butterfly is
comprised of a single unit and is considered occupied. The critical
habitat designation consists of 812 ac (329 ha) and is owned and
managed by NPS, BLM, DHS, WDNR, San Juan County, and private
landowners. In these areas, any actions that may affect the species or
its habitat would also affect designated critical habitat, and it is
unlikely that any additional conservation efforts will be recommended
to address the adverse modification standard over and above those
recommended as necessary to avoid jeopardizing the continued existence
of the island marble butterfly. Therefore, the potential incremental
economic impacts of the island marble butterfly critical habitat
designation are expected to be limited to administrative costs. We
anticipate that the incremental administrative costs of addressing
adverse modification of the island marble butterfly critical habitat in
a section 7 consultation will be minor.
Total annualized incremental costs of critical habitat designation
for the island marble butterfly are anticipated to be less than
$150,000 over the next 20 years, or approximately $10,000 annually. The
incremental administrative burden resulting from the designation of
critical habitat for the island marble butterfly is not anticipated to
reach $100 million in any given year based on the anticipated annual
number of consultations and associated consultation costs, which are
not expected to exceed $10,000 in most years.
Exclusions
Exclusions Based on Economic Impacts
The Service considered the economic impacts of the critical habitat
designation and the Secretary is not exercising his discretion to
exclude any areas from this designation of critical habitat for the
island marble butterfly based on economic impacts.
A copy of the IEM and screening analysis with supporting documents
may be obtained by contacting the Washington Fish and Wildlife Office
(see FOR FURTHER INFORMATION CONTACT) or by downloading from the
internet at https://www.regulations.gov.
Exclusions Based on Impacts on National Security and Homeland Security
Section 4(a)(3)(B)(i) of the Act may not cover all DoD lands or
areas that pose potential national-security concerns (e.g., a DoD
installation that is in the process of revising its INRMP for a newly
listed species or a species previously not covered). If a particular
area is not covered under section 4(a)(3)(B)(i) of the Act, national-
security or homeland-security concerns are not a factor in the process
of determining what areas meet the definition of ``critical habitat.''
Nevertheless, when designating critical habitat under section 4(b)(2),
the Service must consider impacts on national security, including
homeland security, on lands or areas not covered by section
4(a)(3)(B)(i) of the Act. Accordingly, we will always consider for
exclusion from the designation areas for which DoD, Department of
Homeland Security (DHS), or another Federal agency has requested
exclusion based on an assertion of national-security or homeland-
security concerns.
We cannot, however, automatically exclude requested areas. When
DoD, DHS, or another Federal agency requests exclusion from critical
habitat on the basis of national-security or homeland-security impacts,
it must provide a reasonably specific justification of an incremental
impact on national security that would result from the designation of
that specific area as critical habitat. That justification could
include demonstration of probable impacts, such as impacts to ongoing
border-security patrols and surveillance activities, or a delay in
training or facility construction, as a result of compliance with
section 7(a)(2) of the Act. If the agency requesting the exclusion does
not provide us with a reasonably specific justification, we will
contact the agency to recommend that it provide a specific
justification or clarification of its concerns relative to the probable
incremental impact that could result from the designation. If the
agency provides a reasonably specific justification, we will defer to
the expert judgment of DoD, DHS, another Federal agency as to: (1)
Whether activities on its lands or waters, or its activities on other
lands or waters, have national-security or homeland-security
implications; (2) the importance of those implications; and (3) the
degree to which the cited implications would be adversely affected in
the absence of an exclusion. In that circumstance, in conducting a
discretionary 4(b)(2) exclusion analysis, we will give great weight to
national-security and homeland-security concerns in analyzing the
benefits of exclusion.
Department of Homeland Security currently owns 5 ac (2 ha) of land
that is surrounded by land owned and managed by BLM and lies within the
critical habitat boundary. Specifically, these lands include a
lighthouse facility that is managed by the U.S. Coast Guard. The U.S.
Coast Guard is in the process of transferring ownership of these lands
to BLM; therefore, we anticipate no impact on national security from
the inclusion of these lands in the critical habitat designation.
Consequently, the Secretary is not intending to exercise his discretion
to exclude any areas from the final designation based on impacts on
national security.
Exclusions Based on Other Relevant Impacts
Under section 4(b)(2) of the Act, we consider any other relevant
impacts, in addition to economic impacts and impacts on national
security. We consider a number of factors including whether there are
permitted conservation plans covering the species in the area such as
HCPs, safe harbor agreements, or candidate conservation agreements with
assurances (CCAA), or whether there are non-permitted conservation
agreements and partnerships that would be encouraged by designation of,
or exclusion from, critical habitat. In addition, we look at the
existence of tribal conservation plans and partnerships and consider
the government-to-government relationship of the United States with
tribal entities. We also consider any social impacts that might occur
because of the designation.
In preparing this final rule, we have determined that there are
currently no non-permitted conservation agreements or partnerships for
the island marble butterfly. There is a CCAA which is designed to
provide non-federal landowners with the opportunity to create and
maintain habitat for the island marble butterfly while providing
incidental take coverage and regulatory certainty. The final
designation does not include any tribal lands or tribal trust
resources. We anticipate no impact on tribal lands, partnerships,
permitted or non-permitted plans or agreements from this critical
habitat designation. Accordingly, the Secretary is not exercising his
discretion to exclude any areas from this final designation based on
other relevant impacts.
[[Page 26816]]
Required Determinations
Regulatory Planning and Review (Executive Orders 12866 and 13563)
Executive Order 12866 provides that the Office of Information and
Regulatory Affairs (OIRA) will review all significant rules. The Office
of Information and Regulatory Affairs has determined that this rule is
not significant.
Executive Order 13563 reaffirms the principles of E.O. 12866 while
calling for improvements in the nation's regulatory system to promote
predictability, to reduce uncertainty, and to use the best, most
innovative, and least burdensome tools for achieving regulatory ends.
The executive order directs agencies to consider regulatory approaches
that reduce burdens and maintain flexibility and freedom of choice for
the public where these approaches are relevant, feasible, and
consistent with regulatory objectives. E.O. 13563 emphasizes further
that regulations must be based on the best available science and that
the rulemaking process must allow for public participation and an open
exchange of ideas. We have developed this rule in a manner consistent
with these requirements.
Executive Order 13771
This rule is not an E.O. 13771 (``Reducing Regulation and
Controlling Regulatory Costs'') (82 FR 9339, February 3, 2017)
regulatory action because this rule is not significant under E.O.
12866.
Regulatory Flexibility Act (5 U.S.C. 601 et seq.)
Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.),
as amended by the Small Business Regulatory Enforcement Fairness Act of
1996 (SBREFA; 5 U.S.C. 801 et seq.), whenever an agency is required to
publish a notice of rulemaking for any proposed or final rule, it must
prepare and make available for public comment a regulatory flexibility
analysis that describes the effects of the rule on small entities
(i.e., small businesses, small organizations, and small government
jurisdictions). However, no regulatory flexibility analysis is required
if the head of the agency certifies the rule will not have a
significant economic impact on a substantial number of small entities.
The SBREFA amended the RFA to require Federal agencies to provide a
certification statement of the factual basis for certifying that the
rule will not have a significant economic impact on a substantial
number of small entities.
According to the Small Business Administration, small entities
include small organizations such as independent nonprofit
organizations; small governmental jurisdictions, including school
boards and city and town governments that serve fewer than 50,000
residents; and small businesses (13 CFR 121.201). Small businesses
include manufacturing and mining concerns with fewer than 500
employees, wholesale trade entities with fewer than 100 employees,
retail and service businesses with less than $5 million in annual
sales, general and heavy construction businesses with less than $27.5
million in annual business, special trade contractors doing less than
$11.5 million in annual business, and agricultural businesses with
annual sales less than $750,000. To determine if potential economic
impacts to these small entities are significant, we considered the
types of activities that might trigger regulatory impacts under this
designation as well as types of project modifications that may result.
In general, the term ``significant economic impact'' is meant to apply
to a typical small business firm's business operations.
The Service's current understanding of the requirements under the
RFA, as amended, and following recent court decisions, is that Federal
agencies are only required to evaluate the potential incremental
impacts of rulemaking on those entities directly regulated by the
rulemaking itself, and are, therefore, not required to evaluate the
potential impacts to indirectly regulated entities. The regulatory
mechanism through which critical habitat protections are realized is
section 7 of the Act, which requires Federal agencies, in consultation
with the Service, to ensure that any action authorized, funded, or
carried out by the agency is not likely to destroy or adversely modify
critical habitat. Therefore, under section 7, only Federal action
agencies are directly subject to the specific regulatory requirement
(avoiding destruction and adverse modification) imposed by critical
habitat designation. Consequently, it is our position that only Federal
action agencies will be directly regulated by this designation. There
is no requirement under the RFA to evaluate the potential impacts to
entities not directly regulated. Moreover, Federal agencies are not
small entities. Therefore, because no small entities are directly
regulated by this rulemaking, the Service certifies that the final
critical habitat designation will not have a significant economic
impact on a substantial number of small entities.
During the development of this final rule, we reviewed and
evaluated all information submitted during the comment period that may
pertain to our consideration of the probable incremental economic
impacts of this critical habitat designation. Based on this
information, we affirm our certification that this final critical
habitat designation will not have a significant economic impact on a
substantial number of small entities, and a regulatory flexibility
analysis is not required.
Energy Supply, Distribution, or Use--Executive Order 13211
Executive Order 13211 (Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use) requires
agencies to prepare Statements of Energy Effects when undertaking
certain actions. OMB has provided guidance for implementing this
Executive Order that outlines nine outcomes that may constitute ``a
significant adverse effect'' when compared to not taking the regulatory
action under consideration. The economic analysis finds that none of
these criteria is relevant to this analysis. Thus, based on information
in the economic analysis, energy-related impacts associated with island
marble butterfly conservation activities within critical habitat are
not expected. As such, the designation of critical habitat is not
expected to significantly affect energy supplies, distribution, or use.
Therefore, this action is not a significant energy action, and no
Statement of Energy Effects is required.
Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)
In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501
et seq.), we make the following findings:
(1) This rule will not produce a Federal mandate. In general, a
Federal mandate is a provision in legislation, statute, or regulation
that would impose an enforceable duty upon State, local, or tribal
governments, or the private sector, and includes both ``Federal
intergovernmental mandates'' and ``Federal private sector mandates.''
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal
intergovernmental mandate'' includes a regulation that ``would impose
an enforceable duty upon State, local, or tribal governments'' with two
exceptions. It excludes ``a condition of Federal assistance.'' It also
excludes ``a duty arising from participation in a voluntary Federal
program,'' unless the regulation ``relates to a then-existing Federal
program under which $500,000,000 or more is provided annually to State,
local, and tribal governments under entitlement
[[Page 26817]]
authority,'' if the provision would ``increase the stringency of
conditions of assistance'' or ``place caps upon, or otherwise decrease,
the Federal Government's responsibility to provide funding,'' and the
State, local, or tribal governments ``lack authority'' to adjust
accordingly. At the time of enactment, these entitlement programs were:
Medicaid; Aid to Families with Dependent Children work programs; Child
Nutrition; Food Stamps; Social Services Block Grants; Vocational
Rehabilitation State Grants; Foster Care, Adoption Assistance, and
Independent Living; Family Support Welfare Services; and Child Support
Enforcement. ``Federal private sector mandate'' includes a regulation
that ``would impose an enforceable duty upon the private sector, except
(i) a condition of Federal assistance or (ii) a duty arising from
participation in a voluntary Federal program.''
The designation of critical habitat does not impose a legally
binding duty on non-Federal Government entities or private parties.
Under the Act, the only regulatory effect is that Federal agencies must
ensure that their actions do not destroy or adversely modify critical
habitat under section 7. While non-Federal entities that receive
Federal funding, assistance, or permits, or that otherwise require
approval or authorization from a Federal agency for an action, may be
indirectly impacted by the designation of critical habitat, the legally
binding duty to avoid destruction or adverse modification of critical
habitat rests squarely on the Federal agency. Furthermore, to the
extent that non-Federal entities are indirectly impacted because they
receive Federal assistance or participate in a voluntary Federal aid
program, the Unfunded Mandates Reform Act would not apply, nor would
critical habitat shift the costs of the large entitlement programs
listed above onto State governments.
(2) We do not believe that this rule will significantly or uniquely
affect small governments because the area included in the critical
habitat designation is largely owned by Federal and State agencies
(greater than 95 percent). None of these government entities fits the
definition of ``small government jurisdiction.'' Consequently, we do
not believe that the critical habitat designation would significantly
or uniquely affect small government entities. As such, a Small
Government Agency Plan is not required.
Takings--Executive Order 12630
In accordance with E.O. 12630 (Government Actions and Interference
with Constitutionally Protected Private Property Rights), we have
analyzed the potential takings implications of designating critical
habitat for the island marble butterfly in a takings implications
assessment. The Act does not authorize the Service to regulate private
actions on private lands or confiscate private property as a result of
critical habitat designation. Designation of critical habitat does not
affect land ownership, or establish any closures or restrictions on use
of or access to the designated areas. Furthermore, the designation of
critical habitat does not affect landowner actions that do not require
Federal funding or permits, nor does it preclude development of habitat
conservation programs or issuance of incidental take permits to permit
actions that do require Federal funding or permits to go forward.
However, Federal agencies are prohibited from carrying out, funding, or
authorizing actions that would destroy or adversely modify critical
habitat. A takings implications assessment has been completed and
concludes that this designation of critical habitat for the island
marble butterfly does not pose significant takings implications for
lands within or affected by the designation.
Federalism--Executive Order 13132
In accordance with E.O. 13132 (Federalism), this rule does not have
significant federalism effects. A federalism summary impact statement
is not required. In keeping with Department of the Interior and
Department of Commerce policy, we requested information from, and
coordinated development of this critical habitat designation with,
appropriate State resource agencies in Washington. We did not receive
comments from Washington Department of Fish and Wildlife. From a
federalism perspective, the designation of critical habitat directly
affects only the responsibilities of Federal agencies. The Act imposes
no other duties with respect to critical habitat, either for States and
local governments, or for anyone else. As a result, the rule does not
have substantial direct effects either on the States, or on the
relationship between the national government and the States, or on the
distribution of powers and responsibilities among the various levels of
government. The designation may have some benefit to these governments
because the areas that contain the features essential to the
conservation of the species are more clearly defined, and the physical
and biological features of the habitat necessary to the conservation of
the species are specifically identified. This information does not
alter where and what federally sponsored activities may occur. However,
it may assist these local governments in long-range planning (because
these local governments no longer have to wait for case-by-case section
7 consultations to occur).
Where State and local governments require approval or authorization
from a Federal agency for actions that may affect critical habitat,
consultation under section 7(a)(2) will be required. While non-Federal
entities that receive Federal funding, assistance, or permits, or that
otherwise require approval or authorization from a Federal agency for
an action, may be indirectly impacted by the designation of critical
habitat, the legally binding duty to avoid destruction or adverse
modification of critical habitat rests squarely on the Federal agency.
Civil Justice Reform--Executive Order 12988
In accordance with Executive Order 12988 (Civil Justice Reform),
the Office of the Solicitor has determined that the rule does not
unduly burden the judicial system and that it meets the applicable
standards set forth in sections 3(a) and 3(b)(2) of the Order. We are
designating critical habitat in accordance with the provisions of the
Act. To assist the public in understanding the habitat needs of the
species, the rule identifies the elements of physical or biological
features essential to the conservation of the island marble butterfly.
The designated areas of critical habitat are presented on maps, and the
rule provides several options for the interested public to obtain more
detailed location information, if desired.
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)
This rule does not contain any new collections of information that
require approval by the Office of Management and Budget (OMB) under the
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.). An agency may
not conduct or sponsor, and a person is not required to respond to, a
collection of information unless it displays a currently valid OMB
control number.
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act
[[Page 26818]]
(NEPA; 42 U.S.C. 4321 et seq.), need not be prepared in connection with
listing a species as an endangered or threatened species under the
Endangered Species Act. We published a notice outlining our reasons for
this determination in the Federal Register on October 25, 1983 (48 FR
49244).
It is our position that, outside the jurisdiction of the U.S. Court
of Appeals for the Tenth Circuit, we do not need to prepare
environmental analyses pursuant to NEPA in connection with designating
critical habitat under the Act. We published a notice outlining our
reasons for this determination in the Federal Register on October 25,
1983 (48 FR 49244). This position was upheld by the U.S. Court of
Appeals for the Ninth Circuit (Douglas County v. Babbitt, 48 F.3d 1495
(9th Cir. 1995), cert. denied 516 U.S. 1042 (1996)).
Government-to-Government Relationship With Tribes
In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with recognized Federal
Tribes on a government-to-government basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
Federal-Tribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge our responsibilities to work directly with
tribes in developing programs for healthy ecosystems, to acknowledge
that tribal lands are not subject to the same controls as Federal
public lands, to remain sensitive to Indian culture, and to make
information available to tribes. We determined that there are no tribal
lands occupied by the island marble butterfly at the time of listing
that contain the physical or biological features essential to
conservation of the species, and no tribal lands unoccupied by the
island marble butterfly that are essential for the conservation of the
species. Therefore, we are not designating critical habitat for the
island marble butterfly on tribal lands.
References Cited
A complete list of references cited in this rulemaking is available
on the internet at https://www.regulations.gov and upon request from the
Washington Fish and Wildlife Office (see FOR FURTHER INFORMATION
CONTACT).
Authors
The primary authors of this final rule are the staff members of the
Washington Fish and Wildlife Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as set forth below:
PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless
otherwise noted.
0
2. Amend Sec. 17.11(h) by adding an entry for ``Butterfly, island
marble'' to the List of Endangered and Threatened Wildlife in
alphabetical order under ``INSECTS'' to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
----------------------------------------------------------------------------------------------------------------
Listing citations and
Common name Scientific name Where listed Status applicable rules
----------------------------------------------------------------------------------------------------------------
* * * * * * *
----------------------------------------------------------------------------------------------------------------
INSECTS
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Butterfly, island marble........ Euchloe ausonides Wherever found.... E 85 FR [insert Federal
insulanus. Register page where
the document begins],
5/5/2020; 50 CFR
17.95(i).CH
* * * * * * *
----------------------------------------------------------------------------------------------------------------
0
3. In Sec. 17.95, amend paragraph (i) by adding an entry for ``Island
Marble Butterfly (Euchloe ausonides insulanus)'' in the same
alphabetical order that the species appears in the table at Sec.
17.11(h), to read as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(i) Insects.
* * * * *
Island Marble Butterfly (Euchloe ausonides insulanus)
(1) The critical habitat unit is depicted for San Juan County,
Washington, on the map below.
(2) Within the critical habitat area on San Juan Island,
Washington, the physical or biological features essential to the
conservation of the island marble butterfly consist of the following
components:
(i) Open, primarily treeless areas with short-statured forb- and
grass-dominated vegetation that include diverse topographic features
such as ridgelines, hills, and bluffs for patrolling, dispersal
corridors between habitat patches, and some south-facing terrain. Areas
must be large enough to allow for the development of patchy-population
dynamics, allowing for multiple small populations to establish within
the area.
(ii) Low- to medium-density larval host plants, with both flower
buds and blooms on them between the months of May through July, for
egg-laying and larval development. Larval host plants may be any of the
following: Brassica rapa, Sisymbrium altissimum, or Lepidium
virginicum.
(iii) Adult nectar resources in flower and short-statured, white-
flowering plants in bloom used for mate-finding, which may include, but
are not limited to, Abronia latifolia (yellow sand verbena), Achillea
millefolium (yarrow), Amsinckia menziesii (small-flowered fiddleneck),
Cakile edentula (American sea rocket), Cerastium arvense (field
chickweed), Erodium cicutarium
[[Page 26819]]
(common stork's bill), Geranium molle (dovefoot geranium), Hypochaeris
radicata (hairy cat's ear), Lomatium utriculatum (common lomatium),
Lupinus littoralis (seashore lupine), Myosotis discolor (common forget-
me-not), Ranunculus californicus (California buttercup), Rubus ursinus
(trailing blackberry), Taraxacum officinale (dandelion), Toxicoscordion
venenosum (death camas, formerly known as Zigadenus venenosus), and
Triteleia grandiflora (Howell's brodiaea, formerly Brodiaea howellii).
(iv) Areas of undisturbed vegetation surrounding larval host plants
sufficient to provide secure sites for diapause and pupation. The
vegetation surrounding larval host plants must be left standing for a
sufficient period of time for the island marble butterfly to complete
its life cycle.
(3) Critical habitat includes road shoulders and road margins, but
does not include other manmade structures (such as buildings,
aqueducts, runways, paved portions of roads, and other paved areas) and
the land on which they are located existing within the legal boundaries
on June 4, 2020.
(4) Critical habitat map unit. Data layers defining the map were
created using 2015 National Agriculture Imagery Program (NAIP) digital
imagery in ArcGIS, version 10.4 (Environmental Systems Research
Institute, Inc.), a computer geographic information system program. The
map in this entry, as modified by any accompanying regulatory text,
establishes the boundaries of the critical habitat designation. The
coordinates or plot points or both on which the map is based are
available to the public at the Service's internet site at https://www.fws.gov/wafwo/, at https://www.regulations.gov at Docket No. FWS-R1-
ES-2016-0145, and at the field office responsible for this designation.
You may obtain field office location information by contacting one of
the Service regional offices, the addresses of which are listed at 50
CFR 2.2.
(5) Island marble butterfly critical habitat, San Juan County,
Washington.
(i) Island marble butterfly critical habitat consists of 812 acres
(ac) (329 hectares (ha)) on San Juan Island in San Juan County,
Washington, and is composed of lands in Federal (742 ac (301 ha)),
State (37 ac (15 ha)), State/County joint (1 ac (0.4 ha)), County (30
ac (12 ha)), and private (2 ac (0.8 ha)) ownership. The critical
habitat designated on private parcels along Eagle Cove only includes
the area of steep coastal bluff between the marine shoreline and the
upland edge at the top of the bluff; it does not include areas landward
of the top of the bluff, which are typically mowed and maintained as
yard.
(ii) Map of island marble butterfly critical habitat follows:
BILLING CODE 433-15-P
[[Page 26820]]
[GRAPHIC] [TIFF OMITTED] TR05MY20.000
* * * * *
Signed:
Aurelia Skipwith,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2020-07856 Filed 5-4-20; 8:45 am]
BILLING CODE 4333-15-C
