Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List Thorne's Hairstreak Butterfly as or Endangered, 17062-17070 [2010-7547]
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Federal Register / Vol. 75, No. 64 / Monday, April 5, 2010 / Rules and Regulations
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either system, the details thereof may be
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[FR Doc. 2010–7567 Filed 4–2–10; 8:45 am]
BILLING CODE 6712–01–P
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2010-0016]
[MO 92210-0-0008-B2]
Endangered and Threatened Wildlife
and Plants; 90-Day Finding on a
Petition To List Thorne’s Hairstreak
Butterfly as or Endangered
AGENCY: Fish and Wildlife Service,
Interior.
ACTION: Notice of petition finding and
initiation of status review.
SUMMARY: We, the U.S. Fish and
Wildlife Service (Service), announce a
90–day finding on a petition to list
Thorne’s hairstreak butterfly
(Callophrys [Mitoura] grynea thornei or
Callophrys [Mitoura] thornei) as
endangered under the Endangered
Species Act of 1973, as amended and to
designate critical habitat. We find the
petition and information currently
available in our records presents
substantial scientific or commercial
information indicating that listing
Thorne’s hairstreak butterfly may be
warranted. Therefore, with the
publication of this notice, we are
initiating a status review to determine if
the petitioned action is warranted. To
ensure that the status review is
comprehensive, we are requesting
scientific and commercial data and
other information regarding this species.
Based on the status review, we will
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issue a 12–month finding on the
petition, which will address whether
the petitioned action is warranted, as
provided in section 4(b)(3)(B) of the Act.
DATES: To allow us adequate time to
conduct this review, we request that we
receive information on or before June 4,
2010. After this date, you must submit
information directly to the Carlsbad
Fish and Wildlife Office (see FOR
FURTHER INFORMATION CONTACT section
below). Please note that we may not be
able to address or incorporate
information that we receive after the
above requested date.
ADDRESSES: You may submit comments
by one of the following methods:
• Federal eRulemaking Portal: https://
www.regulations.gov. Search for Docket
No. FWS-R8-ES-2010-0016 and then
follow the instructions for submitting
comments.
• U.S. mail or hand-delivery: Public
Comments Processing, Attn: FWS-R8ES-2010-0016; Division of Policy and
Directives Management; U.S. Fish and
Wildlife Service; 4401 N. Fairfax Drive,
Suite 222; Arlington, VA 22203.
We will post all information received
on https://www.regulations.gov. This
generally means that we will post any
personal information you provide us
(see the Information Requested section
below for more details).
FOR FURTHER INFORMATION CONTACT: Jim
Bartel, Field Supervisor, Carlsbad Fish
and Wildlife Office, U.S. Fish and
Wildlife Service, 6010 Hidden Valley
Road, Suite 101, Carlsbad, CA 92011; by
telephone at 760–431–9440; or by
facsimile to 760–431–9624. Persons who
use a telecommunications device for the
deaf (TDD) may call the Federal
Information Relay Service (FIRS) at
800–877–8339.
SUPPLEMENTARY INFORMATION:
Information Requested
When we make a finding that a
petition presents substantial
information indicating that listing a
species may be warranted, we are
required to promptly review the status
of the species (status review). For the
status review to be complete and based
on the best available scientific and
commercial information, we request
information on the Thorne’s hairstreak
butterfly from governmental agencies,
Native American Tribes, the scientific
community, industry, and any other
interested parties. We seek information
on:
(1) The species’ biology, range, and
population trends, including:
(a) Habitat requirements for feeding,
breeding, and sheltering;
(b) Genetics and taxonomy;
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(c) Historical and current range
including distribution patterns;
(d) Historical and current population
levels, and current and projected trends;
and
(e) Past and ongoing conservation
measures for the species and/or its
habitat or both.
(2) The factors that are the basis for
making a listing/delisting/downlisting
determination for a species under
section 4(a) of the Endangered Species
Act of 1973, as amended (Act) (16
U.S.C. 1531 et seq.), which are:
(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.
(3) The historical and current status
and distribution of the Thorne’s
hairstreak butterfly, its biology and
ecology, and ongoing conservation
measures for the species and its habitat
in the United States and Mexico.
(4) Information on management
programs for the conservation of the
Thorne’s hairstreak butterfly.
Please include sufficient information
with your submission (such as full
references) to allow us to verify any
scientific or commercial information
you include.
If, after the status review, we
determine that listing the Thorne’s
hairstreak butterfly is warranted, we
intend to propose critical habitat (see
definition in section 3(5)(A) of the Act),
in accordance with section 4 of the Act,
to the maximum extent prudent and
determinable at the time we propose to
list the species. Therefore, within the
geographical range currently occupied
by the Thorne’s hairstreak butterfly, we
request data and information on:
(1) What may constitute ‘‘physical or
biological features essential to the
conservation of the species,’’
(2) Where these features are currently
found, and
(3) Whether any of these features may
require special management
considerations or protection.
In addition, we request data and
information on ‘‘specific areas outside
the geographical area occupied by the
species’’ that are ‘‘essential to the
conservation of the species.’’ Please
provide specific comments and
information as to what, if any, critical
habitat you think we should propose for
designation if the species is proposed
for listing, and why such habitat meets
the requirements of section 4 of the Act.
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Submissions merely stating support
for or opposition to the action under
consideration without providing
supporting information, although noted,
will not be considered in making a
determination. Section 4(b)(1)(A) of the
Act directs that determinations as to
whether any species is an endangered or
threatened species must be made ‘‘solely
on the basis of the best scientific and
commercial data available.’’
You may submit your information
concerning this status review by one of
the methods listed in the ADDRESSES
section. If you submit information via
https://www.regulations.gov, your entire
submission—including any personal
identifying information—will be posted
on the website. If you submit a
hardcopy that includes personal
identifying information, you may
request at the top of your document that
we withhold this personal identifying
information from public review.
However, we cannot guarantee that we
will be able to do so. We will post all
hardcopy submissions on https://
www.regulations.gov.
Information and supporting
documentation that we received and
used in preparing this finding, will be
available for you to review at https://
www.regulations.gov, or you may make
an appointment during normal business
hours at the U.S. Fish and Wildlife
Service, Carlsbad Fish and Wildlife
Office (see FOR FURTHER INFORMATION
CONTACT).
Background
Section 4(b)(3)(A) of the Act requires
that we make a finding on whether a
petition to list, delist, or reclassify a
species presents substantial scientific or
commercial information indicating that
the petitioned action may be warranted.
We are to base this finding on
information provided in the petition,
supporting information submitted with
the petition, and information otherwise
available in our files. To the maximum
extent practicable, we are to make this
finding within 90 days of our receipt of
the petition and publish our notice of
the finding promptly in the Federal
Register.
Our standard for substantial scientific
or commercial information within the
Code of Federal Regulations (CFR) with
regard to a 90–day petition finding is
‘‘that amount of information that would
lead a reasonable person to believe that
the measure proposed in the petition
may be warranted’’ (50 CFR 424.14(b)).
If we find that substantial scientific or
commercial information was presented,
we are required to promptly review the
status of the species, which is
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subsequently summarized in our 12–
month finding.
Previous Federal Actions
On August 8, 2006, we published 90–
day findings for both the Thorne’s
hairstreak and the Hermes copper
butterfly in the Federal Register. The
findings concluded that the petitions
and information in our files did not
present substantial scientific or
commercial information indicating that
listing Thorne’s hairstreak (71 FR
44980) or Hermes copper butterflies (71
FR 44966) was warranted. (For a
detailed history of Federal actions
involving the Thorne’s hairstreak
butterfly prior to the 2006 90–day
finding, please see the August 8, 2006
Federal Register Notice (71 FR 44980)).
On March 17, 2009, CBD and David
Hogan filed a complaint for declaratory
and injunctive relief challenging the
Service’s decision not to list the
Thorne’s hairstreak butterfly and the
Hermes copper butterfly as threatened
or endangered under the Act. In a
settlement agreement dated October 23,
2009 (Case No. 09-0533 S.D. Cal.), the
Service agreed to submit new 90–day
petition findings to the Federal Register
by April 2, 2010, for the Thorne’s
hairstreak butterfly, and by May 13,
2010, for the Hermes copper butterfly.
As a part of the settlement agreement,
we agreed to evaluate the October 25,
2004 petition filed by David Hogan and
CBD, supporting information submitted
with the petition, and information
available in the Service’s files, including
information that has become available
since the publication of the negative 90–
day findings on August 8, 2006. If the
90–day findings determine that listing
may be warranted, we agreed to submit
a 12–month finding to the Federal
Register by March 4, 2011, for the
Thorne’s hairstreak butterfly, and by
April 15, 2011, for the Hermes copper
butterfly.
This notice constitutes our 90–day
finding on the petition to list Thorne’s
hairstreak butterfly under section
4(b)(1)(A) of the Act. We will publish
the 90–day finding on the petition to list
Hermes copper butterfly in a future
Federal Register document.
Species Information
Taxonomy
Thorne’s hairstreak butterfly was first
described by John Brown (1983) based
on a specimen collected by Fred Thorne
in 1972. In this description, Brown
placed the new species in the
Lycaenidae family with the scientific
name Mitoura thornei. The taxonomic
ranking and placement of Mitoura
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thornei was evaluated in 1999 by the
Committee on Scientific Names of North
American Butterflies and subsequently
changed to a subspecies of Callophrys
gryneus (Faulkner and Klein 2005, p.
31). As a result of this change, the
species was renamed as Callophrys
gryneus thornei. To validate this
nomenclature change, the Service
contracted Dr. Richard W. Van Bursick
(2004) to review the Thorne’s hairstreak
butterfly’s taxonomic status. This
review concurred with the Committee
on Scientific Names of North American
Butterflies’ (1999) decision and the
Service currently recognizes Thorne’s
hairstreak butterfly as the subspecies
Callophrys gryneus thornei. There has
been significant discussion and
disagreement by species experts on the
taxonomic placement of this butterfly
species (Faulkner and Klein 2005, p.
31), resulting in our receipt of new
information from a species expert that
disagrees with the previously cited
taxonomic classification of Thorne’s
hairstreak butterfly (Klein 2009, pers.
comm.). Due to the discrepancy over the
taxonomic nomenclature of this species,
we plan to re-evaluate Van Buskirk’s
(2004) review of taxonomic status for
Thorne’s hairstreak butterfly and will
publish the results in the 12–month
finding.
The host plant for Thorne’s hairstreak
butterfly larvae is Hesperocyparis
forbesii (Tecate cypress). This species
had been known for some time in the
literature as Cupressus forbesii.
Cupressus forbesii, and the rest of the
Western Hemisphere taxa of Cupressus
have been segregated as Hesperocyparis
based on phylogenetic comparisons that
support morphological evidence
(Adams et al. 2009, pp. 160–185).
Hesperocyparis forbesii will be the
name recognized for the species in the
upcoming revision of the Jepson Manual
of the Flora of California. This name
will used throughout this and all future
documents referring to this species.
Species Status and Distribution
Thorne’s hairstreak butterfly is
endemic to San Diego County, and more
specifically found exclusively in the
Otay Mountain area (Faulkner and Klein
2005, p. 31). It is dependent on its larval
host plant, Hesperocyparis forbesii, to
complete its lifecycle (Brown 1983), and
is the only plant known on which
Thorne’s hairstreak butterflies lay their
eggs. Adults lay their eggs on H. forbesii
stems where the eggs mature,
subsequently hatch, and larvae feed
until pupation occurs in the duff and
leaf litter at the base of the plant.
Thorne’s hairstreak butterflies have two
hatching or flight periods per year
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(termed bivoltine): the first flight period
occurs in late March to early April and
the second flight period occurs in
September, which is thought to be
dependent on the presence of summer
rains (Faulkner and Klein 2005, p. 32).
Adult Thorne’s hairstreak butterflies are
known to feed throughout the chaparral
ecosystem on the nectar of Eriogonum
fasciculatum (California buckwheat),
Ceanothus tomentosus (Ramona lilac),
and Lotus scoparius (deerweed) in the
vicinity of stands of H. forbesii
(Faulkner and Klein 2005, p. 33). We
received new information as a result of
a recent study indicating that Asclepias
fascicularis (narrowleaf milkweed) is
also used as an adult nectar source by
Thorne’s hairstreak butterfly throughout
the species’ range (Lucas 2009, pers.
comm.). Confirmed observations of
Thorne’s hairstreak butterfly have been
historically reported throughout the
Otay Mountain area and have been
repeatedly reported from O’Neill
Canyon, Little Cedar Canyon, and Cedar
Canyon, all of which are within the
Otay Mountain wilderness (Betzler et al.
2003, pp. 13-14; Martin 2004, pers.
comm.; Faulkner and Klein 2005, p. 32;
Lucas 2009, unpublished data).
Habitat
Hesperocyparis forbesii, a species
generally associated with chaparral, is a
serotinous- (not opening on maturity) or
closed-coned conifer. Typically,its
cones do not open and disperse seed
until after fire, which nearly always
results in the death of the parent tree
(Zedler 1977, p. 456). Cone production
for H. forbesii begins around 10 years of
age (Zedler 1977, p. 456). While Zedler
(1977, p. 456) asserted that maximum
production per tree is not achieved until
individuals reach approximately 50
years of age, Dunn (1986, p. 371)
concluded that a maximum level of
cones per square meter of the cypress
stand is attained at about 35 to 40 years
of age. Hesperocyparis forbesii’s
historical distribution on Otay
Mountain was known to be
approximately 7,500 acres (ac) (3,035
hectares (ha)) (CNDDB 2003).
Hesperocyparis forbesii persistence
may be impacted by wildfires in the
Otay Mountain area. Throughout the
past 35 years, the Otay Mountain area
has been subject to multiple fires of
various levels of severity (Zedler 1977,
p. 456; Keeley and Fotheringham 2003,
pp. 242–243). Service GIS files indicate
that the 2003 Otay/Mine fire footprint
completely covered the known
distribution of H. forbesii in the Otay
Mountain area followed by the 2007
Harris fire that burned a substantial
portion of this area again. Some
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researchers also postulated that an
increase in frequency of fires in the area
may: (1) Result in changing vegetation
structure or type conversion (Zedler
1977, p. 457; Zedler et al. 1983, p. 817;
Keeley and Fotheringham 2003, pp.
243–244), and (2) lead to significant
declines or possible extinction of H.
forbesii in the Otay Mountain area
because adult H. forbesii will not have
the opportunity to reach an age where
reproductive output is high enough to
sustain the population (Zedler 1977, p.
457). While Dunn (1985, p. 5)
concluded that the Otay population was
not in ‘‘immediate danger,’’ he noted that
‘‘an increasing threat of development
and its effects on fire frequency’’
affected this area. Nonetheless, de
Gouvenain and Ansary (2006, pp. 451–
452) reported that the Otay Mountain,
Tecate Peak, and Guatay populations of
H. forbesii ‘‘appeared to be stable or
potentially increasing’’ (i.e., the rate of
population increase or λ > 1).’’ However,
Markovchick-Nicholls (2007, p. 50)
concluded that ‘‘[m]odel results utilizing
available data and incorporating natural
variation suggest that Tecate cypress [in
the United States] will decline under
most fire regime scenarios over the longterm, but that this trend may be difficult
to detect in the short-term.’’ Results from
a recent study on the abundance of H.
forbesii stands (individuals 3.3 ft (1 m)
or higher) indicate there are
approximately 454 ac (184 ha) located
throughout the Otay Mountain area
(Lucas 2009, unpublished data) and
other burned areas contain small (less
than 3.3 ft (1 m)) individuals that have
sprouted since the 2003 and 2007 fires
(Winchell, pers. obs. 2009). These
surveys corroborated historical data
(Betzler et al. 2003) that the oldest
stands occur in Little Cedar Canyon and
the largest stands occur in O’Neal
Canyon (Lucas 2009, unpublished data);
this survey information indicates that
these stands have survived after
repeated fire events. Additionally,
Thorne’s hairstreak butterfly has been
observed perching on H. forbesii and
nectaring on other chaparral plants
during multiple survey periods between
and following the 2003 and 2007 fires
that occurred in the Otay Mountain area
(Betzler et al. 2003, pp. 13-14; Martin
2004, pers. comm.; Faulkner and Klein
2005, p. 32; Lucas 2009, unpublished
data).
For additional species information on
Thorne’s hairstreak butterfly, please
refer to our previous 90–day finding,
which published in the Federal Register
on August 8, 2006 (71 FR 44980).
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Evaluation of Information for this
Finding
Section 4 of the Act (16 U.S.C. 1533),
and its implementing regulations in the
Code of Federal Regulations (CFR) at 50
CFR 424, set forth the procedures for
adding species to the Federal Lists of
Endangered and Threatened Wildlife
and Plants. A species may be
determined to be an endangered or
threatened species due to one or more
of the five factors described in section
4(a)(1) of the Act: (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.
In making this 90–day finding, we
evaluated whether information on
threats to Thorne’s hairstreak butterfly,
as presented in the 2004 petition and
other information available in our files,
is substantial, thereby indicating that
the petitioned action may be warranted.
In the sections that follow, we
summarize information included in the
2004 petition and evaluate any new
information in our files, including
information that has become available
since the publication of the notsubstantial 90–day finding on August 8,
2006. For a detailed evaluation of
threats listed in the petition, please refer
to the previous 90–day finding that
published in the Federal Register on
August 8, 2006 (71 FR 44980).
A. The Present or Threatened
Destruction, Modification, or
Curtailment of the Species’ Habitat or
Range
The petition, its appendices, and
referenced documents discuss the
following threats that are grouped under
Factor A: wildfire, prescribed burns,
grazing, vehicle access and recreation,
and habitat fragmentation.
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Wildfire
Information Provided in the Petition
The petitioners assert that Thorne’s
hairstreak butterfly is vulnerable to
extinction from wildfire, which can
cause direct mortality of individual
butterflies (see discussion under Factor
E) and indirect mortality resulting from
a loss of the species’ larval host plant,
Hesperocyparis forbesii. The petition
further asserts that a single fire may
threaten a significant portion of
Thorne’s hairstreak butterfly’s range
(such as the 2003 fire, as cited in Betzler
et al. 2003, p. 13). Additionally,
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increased fire frequency throughout the
species’ range may result in an increase
in the abundance or an expansion of
highly flammable, invasive, nonnative
plant species, or vegetation type
conversion and the replacement of
chaparral ecosystems with nonnative
plant species, thereby impacting the
habitat on which Thorne’s hairstreak
butterfly depends (Keeley and
Fotheringham 2003, pp. 243-245; Brooks
et al. 2004, pp. 677-688).
Evaluation of Information Provided in
the Petition and Available in Service
Files
Distribution of Thorne’s hairstreak
butterfly is limited to the Otay
Mountain area (part of the San Ysidro
Mountain range in southern San Diego
County, California) and is dependent on
the presence of Hesperocyparis
forebesii, which is the butterfly’s larval
host plant (Brown 1983, pp. 245-254).
The current distribution of H. forbesii in
the Otay Mountain area encompasses
454 ac (183 ha) (Lucas 2009,
unpublished data); however, historical
records indicate that H. forbesii in the
Otay Mountain area once covered
approximately 7,500 ac (3,035 ha)
(CNDDB 2003). Of the current 454 ac
(183 ha) of H. forbesii, approximately
34.7 ac (14 ha) are privately owned, 7.6
ac (3 ha) are owned by California
Department of Fish and Game, and 5.5
ac (2.2 ha) are owned by the City of
Chula Vista. The remaining
approximately 406 ac (164 ha) of H.
forbesii habitat in the Otay Mountain
area occurs within the Bureau of Land
Management (BLM) Otay Mountain
Wilderness (see Factor D for more
information on the Otay Mountain
Wilderness). Confirmed observations of
Thorne’s hairstreak butterfly have been
reported throughout the Otay Mountain
area, but primarily occur from two
canyons: Little Cedar Canyon and Cedar
Canyon both within the Otay Mountain
Wilderness (Betzler et al. 2003, pp. 1314). Thorne’s hairstreak butterfly is a
narrow endemic species with
historically declining habitat throughout
the Otay Mountain area (Brown 1983,
pp. 245-254; BLM 2009(b), p. 3-59);
Congedo and Williams 2009, p. 1).
Information in our files indicates that
wildfires in 2003 and 2007 burned
throughout the Hesperocyparis forbesii
stands in the Otay Mountain area,
which are known to be occupied by
Thorne’s hairstreak butterfly. The rapid
reburning of this area (fire intervals less
than 40 years) may have impacted
mature H. forbesii by keeping them at a
growth stage where reproductive output
is not high enough to sustain the
population of H. forbesii (de Gouvenain
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17065
and Ansary 2006, pp. 447–448;
Markovchick-Nicholls 2007, p. 7);
therefore, the availability of larval
habitat for Thorne’s hairstreak butterfly
may be reduced by wildfires. It is also
possible that replacement of other
chaparral species (i.e., nectar sources)
may have occurred under this fire
regime, thereby removing nectar sources
necessary to support Thorne’s hairstreak
butterfly; however, we have no
information to support the petitioners’
claim, and we will investigate this in
our status review of the species. It is
likely that wildfires will occur within
the range of this species in the future.
Therefore, we find the petition and
information in our files presents
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted due to the threat of shortreturn-interval wildfire.
Prescribed Burns
Information Provided in the Petition
The petitioners state that while
prescribed burns do not appear to be
planned by BLM for the San Ysidro
Mountain range, any that do occur in
the future could compound the threat of
excessive fire to Thorne’s hairstreak
butterflies and Hesperocyparis forbesii.
Evaluation of Information Provided in
the Petition and Available in Service
Files
We did not find substantial
information in the petition or in our
files to indicate prescribed burns by
BLM in the San Ysidro Mountain range
may threaten Thorne’s hairstreak
butterfly. The species and its larval
plant host, Hesperocyparis forbesii,
occur almost exclusively (approximately
90 percent) in the Otay Mountain
Wilderness (see also Factor D). BLM’s
South Coast Resource Management Plan
(South Coast RMP) (BLM 1994)
generally allows prescribed burns;
however, the Otay Mountain Wilderness
has been managed under a policy of
complete fire suppression (Woychok
2006, pers. comm.). In the Cedar Canyon
area, the South Coast RMP states that
BLM will not consider prescribed burns
until 2020 to minimize the risk of
jeopardizing H. forbesii regeneration
after fires (BLM 1994, p. 21).
Additionally, BLM is currently drafting
a revised South Coast RMP that includes
no prescribed burns and follows fire
suppression practices until H. forbesii
returns to its historical fire cycle of 50
years (BLM 2009(b), pp. 4-171-4-172).
After 50 years without fire in a give H.
forbesii stand, BLM would allow
prescribed burns up to 500 ac per year.
However, this new South Coast RMP is
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in an early draft stage and is not
currently being implemented by BLM.
The other locations in the Otay
Mountain area that contain H. forbesii
stands (approximately 10 percent)
receive protection under the City of
Chula Vista Subarea Plan or the County
of San Diego Subarea Plan under the
Multiple Species Conservation Program
(MSCP). These subarea plans require the
conservation of natural vegetation
communities (including H. forbesii
stands), and states that ‘‘a fire
management program would be needed
for prevention of catastrophic fires and
long-term viability’’ of both Thorne’s
hairstreak butterfly and its larval host
plant. Therefore, we find the petition
and information in our files do not
present substantial information
indicating that listing Thorne’s
hairstreak butterfly may be warranted
due to the threat of prescribed burns.
However, we will further investigate the
potential threat of prescribed burns in
our status review for this species.
Grazing
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Information Provided in the Petition
The petition states that grazing may
harm Thorne’s hairstreak butterfly and
its larval host plant, Hesperocyparis
forbesii, if grazing within the currently
vacant Otay Grazing Allotment
(approximately 5,522 ac (2,235 ha)
(BLM 2009(b), p. 3-116) located on BLM
lands on Otay Mountain) occurs in the
future. The threat of grazing as it relates
to direct mortality of individual
butterflies is discussed under Factor E.
The petitioners assert that the allotment
is being considered for renewed grazing
in the future and that cattle grazing will
cause harm to the habitat (by trampling
the larval host and through soil
modification) and increase the
occurrence of nonnative plants, thus
leading to an increase in fire frequency,
and resulting in loss of Thorne’s
hairstreak butterfly habitat.
Evaluation of Information Provided in
the Petition and Available in Service
Files
The petitioners state that the Otay
Grazing Allotment is vacant.
Information in our files indicates the
allotment is leased but has been in a
state of non-use since 2000 (BLM
2009(b), p. 3-120). The Otay Grazing
Allotment is completely contained
within the Otay Mountain Wilderness
and encompasses suitable adult
Thorne’s hairstreak butterfly habitat
(i.e., the host plant and other chaparral
plants, which includes nectar sources
for adults) (Lucas 2009, pers. comm.),
including approximately 16 percent
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Vehicle Access and Recreation
not have information to support the
claim that vehicle access would increase
the fire frequency in the area.
Additionally, we do not have
information in our files and the
petitioners did not present information
to indicate that vehicle access and
recreation are a threat to the species in
the Otay Mountain Wilderness or in
privately-owned areas. Therefore, we
find the petition and information in our
files do not present substantial
information indicating that listing
Thorne’s hairstreak butterfly may be
warranted due to the threat of vehicle
access and recreation. However, we will
further investigate the potential threat of
recreation and vehicle access in our
status review for this species.
Information Provided in the Petition
Habitat Fragmentation
(75.2 ac (30.4 ha)) of the Hesperocyparis
forbesii in the Otay Mountain area. The
available adult and larval habitat for
Thorne’s hairstreak butterfly is currently
not impacted by grazing and a large
majority of the adult and larval habitat
would remain unaffected if grazing
resumed in the Otay Grazing Allotment
in the future. Neither the petition nor
other information in our files presents
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted due to the threat of
grazing. However, we will further
investigate the potential threat of
grazing in our status review for this
species.
The petitioners assert that vehicle
access and recreation in the San Ysidro
Mountain range will likely lead to
increased fire frequency. Additionally,
they state that certain roads were
grandfathered into the Otay Mountain
Wilderness designation and generally
allow unrestricted public access to
Thorne’s hairstreak butterfly habitat.
Evaluation of Information Provided in
the Petition and Available in Service
Files
The Otay Mountain Wilderness Area
allows public access; however,
recreational use is considered light with
no more than 1,000 visitor use days per
year (BLM 2009(b), p. 3-103). Visitors
are encouraged to be responsible and
follow the BLM program called ‘‘Leave
No Trace,’’ which minimizes impacts
from human uses. Motorized vehicle use
is not permitted in the designated
Wilderness Area with the exception of
two pre-existing roads, and off-highway
vehicles are completely excluded (BLM
2009(b), pp. 2-124-2-125). The majority
of traffic through the area is
concentrated on a few small roads used
by border patrol agents. Border patrol
vehicles may increase the risk of fire in
this area, although fires are expected to
be immediately reported (BLM 2009(b),
p. 2-151).
Although light recreational use and
minimal traffic associated with border
patrol agents occurs in the Otay
Mountain Wilderness, the information
available to us does not indicate that
recreation and vehicle use is a threat to
Thorne’s hairstreak butterfly. These two
pre-existing roads within the Otay
Mountain Wilderness extend outside of
BLM property onto private lands;
however, they are small, one-lane,
remote, dirt roads that only pass near
stands of Hesperocyparis forbesii and do
not appear to be heavily used. We do
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Information Provided in the Petition
The petitioners claim that both habitat
fragmentation and habitat degradation
pose a substantial threat to Thorne’s
hairstreak butterfly and its habitat
through both habitat modification and
fragmentation of butterfly populations.
The petitioners assert that the habitat
has been degraded and modified such
that Thorne’s hairstreak butterfly is
unable to locate suitable habitat, which
will likely impact the species
throughout its geographical range. The
impacts associated with Thorne’s
hairstreak butterfly population
fragmentation are assessed under Factor
E (see below).
Evaluation of Information Provided in
the Petition and Available in Service
Files
We agree that habitat for Thorne’s
hairstreak butterfly appears to have been
fragmented or degraded by wildfire. The
current distribution of Hesperocyparis
forbesii in the Otay Mountain area
encompasses 454 ac (183 ha) (Lucas
2009, unpublished data) and is
distributed in patches across the
landscape; however, historical records
indicate that H. forbesii in the Otay
Mountain area once covered
approximately 7,500 ac (3,035 ha).
Information in our files indicates that H.
forbesii and other chaparral species are
currently recovering after recent fires
(Congedo and Williams 2009, p. 1;
Lucas 2009, pers. comm.); however, we
do not have information in our files that
indicates whether the habitat has been
impacted in a manner that would
inhibit recovery to historical levels. We
note that the amount of larval habitat
has increased from 2004 to 2009 (Lucas
2009, unpublished data).
Zedler et al. (1983, pp. 809-818)
describes vegetation type conversion
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(also considered a type of habitat
fragmentation) within the Otay
Mountain area; however, information in
our files describes recovering H. forbesii
habitat and availability of various
suitable nectar sources after the fires in
2003 and 2007, including one source
that was previously unknown (Lucas
2009, pers. comm.).
Additionally, the petition cites roads
as a mechanism of habitat
fragmentation; however, roads are
unlikely to cause habitat fragmentation
to an extent that would impact Thorne’s
hairstreak butterfly population because
the roads are small, one-lane, remote,
dirt roads with little traffic. The Otay
Mountain Wilderness, managed by the
BLM, has only two main roads and a
few other small roads that allow
motorized vehicles (off-highway vehicle
use is excluded throughout the Otay
Mountain Wilderness); therefore, habitat
fragmentation resulting from roads
would be very minimal.
In summary, we evaluated the
petition and information in our files and
find that substantial information exists
to indicate that listing Thorne’s
hairstreak butterfly may be warranted
due to the present or threatened
destruction, modification, or
curtailment of the habitat or range of the
species due to the threat of wildfires
and the possibility that habitat
fragmentation may be occurring as a
result of wildfires. We will further
investigate the potential threat of habitat
fragmentation in our status review for
this species.
B. Overutilization for Commercial,
Recreational, Scientific, or Educational
Purposes
Information Provided in the Petition
The petition does not present any
information with respect to Factor B.
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Evaluation of Information Provided in
the Petition and Available in Service
Files
The information in our files does not
indicate any threat to Thorne’s
hairstreak butterfly due to
overutilization for commercial,
recreational, scientific, or education
purposes. Therefore, we find that the
petition and information in our files do
not provide substantial information
indicating listing Thorne’s hairstreak
butterfly may be warranted due to the
overutilization for commercial,
recreational, scientific, or education
purposes. However, we will further
investigate the potential threat of
overutilization for commercial,
recreational, scientific, or education
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purposes in our status review for this
species.
D. The Inadequacy of Existing
Regulatory Mechanisms
C. Disease or Predation
The petition cites three regulatory
mechanisms that may provide some, but
not adequate, Thorne’s hairstreak
butterfly conservation, including:
(1) The Wilderness Act,
(2) BLM management activities, and
(3) The County of San Diego Subarea
Plan under the Multiple Species
Conservation Program (MSCP).
Disease
Information Provided in the Petition
The petition does not present any
information concerning threats from
disease to Thorne’s hairstreak butterfly.
Evaluation of Information Provided in
the Petition and Available in Service
Files
We have no information in our files
to indicate any threat from disease to
Thorne’s hairstreak butterfly.
Predation
Information Provided in the Petition
The petitioners state that species
experts (Klein (date not provided), pers.
comm.) suspect that birds, predatory
insects, parasitic insects, and spiders
prey upon Thorne’s hairstreak butterfly.
Additionally, the petitioners assert that
the harmful effects of otherwise normal
predation or parasitism might be
exacerbated by population reduction
from excessive fires.
Evaluation of Information Provided in
the Petition and Available in Service
Files
Faulkner and Klein (2005, p. 34) state
that birds may consume Thorne’s
hairstreak larvae; however, we are not
aware of any data to support a theory of
bird predation as a significant threat to
Thorne’s hairstreak butterflies.
Brachonid wasps, which are parasitic
insects, have been observed near the
host plant, but there has been no
documentation of parasitism to Thorne’s
hairstreak butterflies (Faulkner and
Klein 2005, p. 34). The petitioners do
not provide information to support their
claim that predation or parasitism may
exacerbate population reduction
resulting from fires, nor do we have any
information in our files to support this
claim.
Neither the petition nor our files
present substantial information that
disease or predation pose significant
threats to Thorne’s hairstreak butterfly.
Therefore, we find that the petition and
information in our files do not provide
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted due to disease or
predation. However, we will further
investigate the potential threat of
disease and predation in our status
review for this species.
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Information Provided in the Petition
The petitioners make the following
statements concerning Thorne’s
hairstreak butterflies and the Wilderness
Act, BLM management activities, and
the County of San Diego Subarea Plan:
(1) The Wilderness Act does not
provide significant protection for the
species;
(2) BLM does not consider the species
as ‘‘sensitive’’, so the species is not
afforded sensitive species’ protections
within the agency’s management plan
(i.e., the South Coast RMP));
(3) BLM is not actively implementing
conservation measures for the species;
(4) BLM is not pro-actively managing
the private lands they have acquired;
and
(5) Despite Thorne’s hairstreak
butterfly being recognized as a ‘‘covered
species’’ under the County of San Diego
Subarea Plan, that Plan does not provide
sufficient protection for the species.
Evaluation of Information Provided in
the Petition and Available in Service
Files
Thorne’s hairstreak butterfly larval
habitat on Otay Mountain occurs almost
entirely (92 percent) on publicly owned
property (BLM, City of Chula Vista or
California Department of Fish and
Game). The following regulatory
mechanisms and management actions
apply to these public lands and protect
Thorne’s hairstreak butterfly and its
habitat:
(1) The Otay Mountain Wilderness
Act (1999) (Pub. L. 106-145) and BLM
management policies provide protection
for the vast majority of Thorne’s
hairstreak butterfly habitat. The Otay
Mountain Wilderness Act provides that
the Otay Mountain designated
wilderness area (i.e., Otay Mountain
Wilderness; 18,500 ac (7,486 ha)) will be
managed in accordance with the
provisions of the Wilderness Act of
1964 (16 U.S.C. 1131 et seq.). The
Wilderness Act of 1964, in turn, strictly
limits use of wilderness areas, imposing
restrictions on vehicle use, new
developments, chainsaws, mountain
bikes, leasing, and mining in order to
protect the natural habitats of the areas,
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maintain species diversity, and enhance
biological values. Finally, any lands
acquired within the Otay Mountain
Wilderness boundaries become part of
the designated wilderness area and they
are managed in accordance with all
provisions of the Wilderness Act and
applicable laws.
(2) Sensitive species, as defined by
BLM, are those species that are not
already designated as Federal- or Statelisted species and occur on Bureauadministered lands for which BLM has
the capability to significantly affect their
conservation status through
management. This BLM policy is
intended to ensure that actions
authorized, funded, or carried out by the
BLM do not contribute to the need for
these species to become listed as
endangered or threatened under the Act
(BLM 2009(b), p. 3-58). Currently,
Thorne’s hairstreak butterfly is not
considered a sensitive species by BLM;
however, BLM is currently collaborating
with the Service to revise the South
Coast RMP. In this draft revised plan,
Thorne’s hairstreak butterfly and
Hesperocyparis forbesii are identified as
sensitive species (BLM 2009(b), p. 3-59),
and the draft revised plan specifically
states the management of these species
and their habitats are important because
of their close association and the
importance of fire cycles to their
continued existence. Moreover, one of
BLM’s primary objectives in the draft
revised plan is improved fire
management and collaboration with
local communities and agencies to
prevent wildfires. Additionally, BLM
intends to write a more specific plan for
the Otay Mountain Wilderness that
identifies management measures and
actions that would benefit H. forbesii
(Schlachter 2006, pers. comm.; BLM
2009(a), p. 1). BLM’s future management
plans appear to provide a significant
amount of conservation and
management measures, but they are
currently not being implemented
throughout the Otay Mountain
Wilderness Area. As a result of wildfires
on Otay Mountain there have likely
been increases in nonnative species
which increase fuels available for future
fires. Furthermore, although the current
fire suppression policy dictates all fires
should be suppressed once ignited, this
has not prevented recent wildlfires from
burning through large areas of Thorne’s
hairstreak butterfly habitat. Therefore, it
appears current regulations for Thorne’s
hairstreak butterfly and its habitat are
not adequate to control the threat of
increased wildfire frequency.
(3) The Memorandum of
Understanding (MOU) on cooperation in
habitat conservation planning and
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management issued by BLM in 1994 in
conjunction with the development of
the County of San Diego Subarea Plan
(BLM 1994, pp. 1-8) applies to the Otay
Mountain Wilderness because it falls
entirely within the boundary of this
subarea plan. The MOU details BLM’s
commitment to manage its lands in a
manner that compliments the County of
San Diego MSCP Subarea Plan, which in
turn, requires protection of Thorne’s
hairstreak butterfly’s larval host plant
and local chaparral species used as
nectar sources. Additionally, the MOU
states that private lands acquired by
BLM will be evaluated for inclusion
within the designated wilderness area
and if the lands do not meet wilderness
qualifications they would be included
in the region’s habitat conservation
system (BLM 1994, p. 3). Any existing
conservation plans will be considered
when managing these newly acquired
lands (BLM 1994, p. 3; BLM 2009(b), pp.
2-74, N-1-2).
The draft revised South Coast RMP
(see discussion in (2) above) , which
covers the Otay Mountain Wilderness,
does provide conservation measures for
both Thorne’s hairstreak butterfly and
Hesperocyparis forbesii. The plan
specifically includes a goal of restoring
fire frequency to 50 years through fire
prevention or suppression and
prescribed burns; once an area has not
burned for 50 years the plan allows for
annual prescribed burning of up to 500
acres (202.3 ha) in the Otay Mountain
Wilderness (BLM 2009(b), pp. 4-171-4172). BLM’s future management plans
appear to provide conservation and
management measures to assist with
various threats to Thorne’s hairstreak
butterfly and its habitat, but they are
currently not being implemented
throughout the Otay Mountain
Wilderness Area; therefore, it appears
that current regulations for Thorne’s
hairstreak butterfly and its habitat are
not adequate to control potential threats
to this species, including the threat of
increased wildfire frequency.
(4) Approximately 48 ac (19 ha) of
Hesperocyparis forbesii habitat fall
under the MSCP, which strives for fire
management and prevention to restore
the previous 25–year fire cycle and
states that ‘‘a fire management program
would be needed for prevention of
catastrophic fires and long-term
viability of its host plant.’’ This shorter
frequency of fire may have an impact on
adult H. forbesii because they will not
have the opportunity to reach an age (40
or more years) where reproductive
output is high enough to sustain the
population (de Gouvenain and Ansary
2006, pp. 447–448; MarkovchickNicholls 2007, p. 7). Therefore, the fire
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management and prevention policies of
the MSCP which strive to restore a 25
year fire cycle, may be inadequate to
control the threat of wildfire to this
species.
There appear to be a variety of future
management actions that BLM
couldimplement which may provide
protection to Thorne’s hairstreak
butterfly and its habitat; however,
current existing regulatory mechanisms
by BLM and MSCP do not appear to be
adequate to provide protection for
Thorne’s hairstreak butterfly or its
habitat from the threat of increased
wildfire frequency. Therefore, after our
evaluation of the petition and
information in our files, we find that
substantial information exists to
indicate that listing Thorne’s hairstreak
butterfly may be warranted due to the
inadequacy of existing regulatory
mechanisms.
E. Other Natural or Manmade Factors
Affecting the Species’ Continued
Existence
The petition, its appendices, and
referenced documents discuss the
following threats that are grouped under
Factor E: wildfire, grazing, population
fragmentation, vulnerability of small
and isolated populations, and global
climate change.
Wildfire
Information Provided in the Petition
The petitioners state that Thorne’s
hairstreak butterfly cannot escape fire.
They stated that: (1) Pupae and larvae
are likely killed when fire burns
Hesperocyparis forbesii stands and
nearby chaparral; (2) adults are likely
killed by fire due to their habit of
remaining close to their host plant; and
(3) adults are likely outpaced by an
approaching fire. The petition claims
excessive fires over the last several
decades have reduced Thorne’s
hairstreak butterfly population numbers
and disrupted metapopulation
dynamics and stability.
Evaluation of Information Provided in
the Petition and Available in Service
Files
We agree that the majority of Thorne’s
hairstreak butterfly individuals are
likely killed when a fire passes through
an occupied area. Moreover, researchers
questioned the persistence of Thorne’s
hairstreak butterfly after the 2003 Otay/
Mine fire because the fire footprint
appeared to cover all areas known to be
occupied by the species (IBAERT 2003,
pp. 219-220; Betzler et al. 2003, p. 13).
Although, adult Thorne’s hairstreak
butterflies were documented from four
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unburned Hesperocyparis forbesii
stands after the 2003 fire on the
southwest slope of the Otay Mountain
(Martin 2004, pers. comm.), surveyors in
2004 visiting the burned areas occupied
prior to the 2003 fire, found evidence of
new host plant growth but no adult
Thorne’s hairstreak butterflies (Faulkner
and Klein 2005, pp. 32). This is likely
due to the lack of available larval host
plants and nectar sources on which
Thorne’s hairstreak butterfly relies one
year after the fire.
Researchers have postulated that
Thorne’s hairstreak butterflies require
mature host plants for reproduction
(Faulkner and Klein 2005, p. 32);
however, Thorne’s hairstreak butterflies
were observed in 2009 perching and
feeding within re-growth areas burned
in the 2003 and 2007 fires (Lucas 2009,
pers. comm.). These observations in
recently burned (younger) stands of H.
forbesii support the theory that Thorne’s
hairstreak butterflies do not strictly
require mature or adult trees as host
plants.
Even with some post-fire adult
observations, it is likely the majority of
Thorne’s hairstreak butterflies killed
when habitat burns and populations are
further adversely impacted by
frequently recurring fires. Therefore, we
find that the petition and information in
our files do provide substantial
information to indicate that listing
Thorne’s hairstreak butterfly may be
warranted due to direct mortality from
wildfire.
Grazing
Information Provided in the Petition
The petitioners assert that grazing
practices may lead to trampling of eggs
and larvae of Thorne’s hairstreak
butterfly.
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Evaluation of Information Provided in
the Petition and Available in Service
Files
The Otay Grazing Allotment, which is
the only place in the current range of
the species that is grazed, is completely
contained within the Otay Mountain
Wilderness and has not been grazed
since 2000 (Doran 2006, pers. comm.;
BLM 2009(b), p. 3-120). Information in
our files indicate that approximately 84
percent (378 ac (153 ha)) of the
Hesperocyparis forbesii within the Otay
Mountain area are outside of the Otay
Grazing Allotment. The majority of the
available habitat for Thorne’s hairstreak
butterfly is currently not affected by
grazing (i.e., vegetation conditions are
not favorable for grazing), and would
not be affected by grazing within the
Otay Grazing Allotment should grazing
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in the allotment resume in the future.
Therefore, we find that the petition and
information in our files do not provide
substantial information to indicate that
listing Thorne’s hairstreak butterfly may
be warranted due to mortality from
grazing. However, we will further
investigate in our status review for this
species the potential threat of trampling
mortality from grazing and the potential
impact that grazing could have if it
occurs in the future.
Population Fragmentation
Information Provided in the Petition
The petitioners state that
fragmentation of Thorne’s hairstreak
butterfly populations through fire,
habitat type conversion, and roads poses
a significant threat to the species. The
petitioners claim habitat fragmentation
reduces the area of Thorne’s hairstreak
butterfly habitat and thereby threatens
the species by isolating populations
from one another. The petitioners also
claim that because Thorne’s hairstreak
butterflies are habitat specialists, they
have a higher risk of extinction due to
population fragmentation than a habitat
generalist. Additionally, the petitioners
claim that habitat fragmentation
expands edge habitat, resulting in
further stress on fragmented or small
populations, leading to isolation effects
on the population.
Evaluation of Information Provided in
the Petition and Available in Service
Files
The petition describes the Thorne’s
hairstreak butterfly population as
fragmented as a result of habitat
fragmentation. Hesperocyparis forbesii
and associated chaparral habitat has
been disturbed by wildfire; however,
this habitat is recovering and Thorne’s
hairstreak butterflies continue to occur
throughout the burned area (Martin
2004, pers. comm.; Faulkner and Klein
2005, pp. 32-33; Congedo and Williams
2009, p. 1; Lucas 2009, pers. comm.).
Even though movement dynamics have
not been completely determined,
information in our files indicates
Thorne’s hairstreak butterfly is capable
of re-colonizing and utilizing immature
H. forbesii stands in recently burned
areas (Martin 2004, pers. comm.;
Faulkner and Klein 2005, p. 32; Lucas
2009, pers. comm.). New information
indicating that Asclepias fascicularis, a
previously unknown nectar source
(Lucas 2009, pers. comm.), is used by
Thorne’s hairstreak butterfly indicate
that the butterfly’s habitat requirements
may not be as specialized as previously
thought.
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The petition states that individuals
have been observed nectaring 0.25 mile
(0.40 kilometer) away from their host
plant, which suggests that individual
butterflies are capable of moving at least
this far to find suitable habitats or
mates. However, information in our files
indicates that the H. forbesii stands are
patchily distributed and separated by
distances greater than 0.25 mile (0.40
kilometer), which may contribute to
population fragmentation. As a result of
this information, we find that the
petition and information in our files
provides substantial information
indicating listing Thorne’s hairstreak
butterfly may be warranted due to
population fragmentation. We intend to
further investigate and attempt to
distinguish between habitat
fragmentation and population
fragmentation in our status review of the
species.
Vulnerability of Small and Isolated
Populations
Information Provided in the Petition
The petitioners assert that endemic
taxa such as Thorne’s hairstreak
butterfly are considered more prone to
extinction than widespread species due
to their restricted geographical range.
According to the petition, the common
factors that increase the vulnerability of
small and isolated populations to
extinction are demographic fluctuations,
environmental stochasticity (random
events), and reduced genetic diversity.
Evaluation of Information Provided in
the Petition and Available in Service
Files
The fact that a species is characterized
by populations that are few in number,
small in size, or isolated does not
necessarily mean the species is
threatened. Typically, it is the
combination of small size and number
of populations and isolation of small
populations in conjunction with other
threats (such as the present or
threatened destruction, modification, or
curtailment of the species’ habitat or
range) that may pose a threat to a
species. Thorne’s hairstreak butterfly
has always been endemic the Otay
Mountains (Brown 1983; Beztler et al.
2003; Faulkner and Klein 2005). If
occupied habitat is temporarily
fragmented by fire, a fluctuation in
Thorne’s hairstreak butterfly numbers
could make small populations more
vulnerable to stochastic events. Small
populations and the isolation of
populations from one another could also
subject Thorne’s hairstreak butterfly to
genetic drift and restrict gene flow that
may decrease genetic variability over
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Federal Register / Vol. 75, No. 64 / Monday, April 5, 2010 / Rules and Regulations
time and could adversely affect the
species’ viability (Allee 1931, pp. 12-37;
Stephens et al. 1999, pp. 185-190;
Dennis 2002, pp. 389-401). Surveys
conducted in 2009 (Lucas 2009,
unpublished data) conclude that
Thorne’s hairstreak butterflies are still
present in the H. forbesii stands on Otay
Mountain. We have no quantitative
survey information on population
numbers, but historical larval habitat
has been reduced from 7,500 ac (3,035
ha) to approximately 454 ac (see
‘‘Habitat’’ section above for more
information). Since Thorne’s hairstreak
butterfly is dependent on H. forbssi to
complete its lifecycle, available larval
habitat is a proxy for population size.
With this large reduction in available
larval habitat we believe that the
species’ population distribution have
been significantly reduced relative to
historical levels resulting in an
increased risk of extinction due to
stochastic events such as wildfire.
Therefore, we find that the petition and
information in our files do provide
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted due to restricted
geographic range.
Global Climate Change
erowe on DSK5CLS3C1PROD with RULES
Information Provided in the Petition
The petitioners assert that butterflies
(in general) are threatened by global
climate change and are sensitive to
small changes in microclimates, such as
fluctuations in moisture, temperature, or
sunlight. According to the petition,
studies of Edith’s checkerspot butterfly
(Euphydryas editha) have verified
speculation that whole ecosystems may
move northward or shift in elevation as
the Earth’s climate warms (Parmesan
and Galbraith 2004, p. 9).
Evaluation of Information Provided in
the Petition and Available in Service
Files
We recognize recent evaluations by
Parmesan and Galbraith (2004, pp. 1–2,
29–33) that indicate whole ecosystems
may be shifting northward and upward
in elevation, or are otherwise being
altered by differing climate tolerance
among species within a community.
Parmesan’s review (2006, pp. 637, 648–
649, 653) indicates range-restricted
mountaintop species (such as Thorne’s
hairstreak butterfly) typically
experience range retractions.
Additionally, we recognize that climate
change is likely to cause changes in the
arrangement of occupied habitat
patches. Current climate change
predictions for terrestrial areas in the
Northern Hemisphere indicate warmer
VerDate Nov<24>2008
13:31 Apr 02, 2010
Jkt 220001
air temperatures, more intense
precipitation events, and increased
summer continental drying (Field et al.
1999, pp. 1–3; Hayhoe et al. 2004, p.
12422; Cayan et al. 2005, p. 6;
Intergovernmental Panel on Climate
Change 2007, p. 11). However,
predictions of climatic conditions for
smaller subregions such as California
remain uncertain. It is unknown at this
time if climate change in California will
result in a warmer trend with localized
drying, higher precipitation events, or
other effects. Because, the information
currently available on the effects of
global climate change and microhabitat
changes, such as increasing
temperatures or moisture, does not
make sufficiently precise estimates of
the magnitude of the effects, we are
unable to determine what impacts to
Thorne’s hairstreak butterfly may occur.
Given this uncertainty, we find that the
petition and information in our files do
not provide substantial information to
indicate that listing Thorne’s hairstreak
butterfly may be warranted do to global
climate change. We will further
investigate this potential threat to
Thorne’s hairstreak butterfly in our
status review of the species.
In summary, we find that the petition
and information in our files do provide
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted due to other natural or
manmade factors affecting the species’
continued existence. Specifically, we
find that the effects of wildfire on
individuals, population fragmentation,
and restricted geographic range+may
pose significant threats to the species.
commercial data’’ standard that applies
to a status review to determine whether
a petitioned action is warranted. A 90–
day finding does not constitute a status
review under the Act. In a 12–month
finding, we will determine whether a
petitioned action is warranted after we
have completed a thorough status
review of the species, which is
conducted following a substantial 90–
day finding. Because the Act’s standards
for 90–day and 12–month findings are
different, as described above, a
substantial 90–day finding does not
mean that the 12–month finding will
result in a warranted finding.
The petitioners request that we
designate critical habitat for this
species. If we determine in our 12–
month finding that listing Thorne’s
hairstreak butterfly is warranted, we
will address the designation of critical
habitat at the time of the proposed
rulemaking. The proposed rulemaking
may be published concurrently with the
12–month finding or at a later date.
Finding
On the basis of our determination
under section 4(b)(3)(A) of the Act, we
have determined that the petition
presents substantial scientific or
commercial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted. This finding is based on
information provided under Factor A
(present or threatened destruction,
modification, or curtailment of the
species’ habitat or range), Factor D (the
inadequacy of existing regulatory
mechanisms) and Factor E (other natural
or manmade factors affecting the
species’ continued existence). Because
we have found that the petition presents
substantial information indicating that
listing Thorne’s hairstreak butterfly may
be warranted, we are initiating a status
review to determine whether listing
Thorne’s hairstreak butterfly under the
Act is warranted.
The ‘‘substantial information’’
standard for a 90–day finding differs
from the Act’s ‘‘best scientific and
The authority for this action is the
Endangered Species Act of 1973, as
amended (16 U.S.C. 1531 et seq.).
PO 00000
Frm 00044
Fmt 4700
Sfmt 4700
References Cited
A complete list of references cited is
available on the Internet at https://
www.regulations.gov and upon request
from the Carlsbad Fish and Wildlife
Office (see FOR FURTHER INFORMATION
CONTACT).
Author
The primary authors of this notice are
staff members of the Carlsbad Fish and
Wildlife Office (see FOR FURTHER
INFORMATION CONTACT).
Authority
Dated: March 26, 2010.
Jeffrey L. Underwood,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010–7547 Filed 4–2–10; 8:45 am]
BILLING CODE 4310–55–S
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric
Administration
50 CFR Part 665
RIN 0648–XU60
Fisheries in the Western Pacific;
Hawaii Bottomfish and Seamount
Groundfish Fisheries; Fishery Closure
AGENCY: National Marine Fisheries
Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA),
Commerce.
E:\FR\FM\05APR1.SGM
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]]>Agencies
[Federal Register Volume 75, Number 64 (Monday, April 5, 2010)]
[Rules and Regulations]
[Pages 17062-17070]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-7547]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2010-0016]
[MO 92210-0-0008-B2]
Endangered and Threatened Wildlife and Plants; 90-Day Finding on
a Petition To List Thorne's Hairstreak Butterfly as or Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of petition finding and initiation of status review.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
90-day finding on a petition to list Thorne's hairstreak butterfly
(Callophrys [Mitoura] grynea thornei or Callophrys [Mitoura] thornei)
as endangered under the Endangered Species Act of 1973, as amended and
to designate critical habitat. We find the petition and information
currently available in our records presents substantial scientific or
commercial information indicating that listing Thorne's hairstreak
butterfly may be warranted. Therefore, with the publication of this
notice, we are initiating a status review to determine if the
petitioned action is warranted. To ensure that the status review is
comprehensive, we are requesting scientific and commercial data and
other information regarding this species. Based on the status review,
we will issue a 12-month finding on the petition, which will address
whether the petitioned action is warranted, as provided in section
4(b)(3)(B) of the Act.
DATES: To allow us adequate time to conduct this review, we request
that we receive information on or before June 4, 2010. After this date,
you must submit information directly to the Carlsbad Fish and Wildlife
Office (see FOR FURTHER INFORMATION CONTACT section below). Please note
that we may not be able to address or incorporate information that we
receive after the above requested date.
ADDRESSES: You may submit comments by one of the following methods:
Federal eRulemaking Portal: https://www.regulations.gov.
Search for Docket No. FWS-R8-ES-2010-0016 and then follow the
instructions for submitting comments.
U.S. mail or hand-delivery: Public Comments Processing,
Attn: FWS-R8-ES-2010-0016; Division of Policy and Directives
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive,
Suite 222; Arlington, VA 22203.
We will post all information received on https://www.regulations.gov. This generally means that we will post any
personal information you provide us (see the Information Requested
section below for more details).
FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad
Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 Hidden
Valley Road, Suite 101, Carlsbad, CA 92011; by telephone at 760-431-
9440; or by facsimile to 760-431-9624. Persons who use a
telecommunications device for the deaf (TDD) may call the Federal
Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Information Requested
When we make a finding that a petition presents substantial
information indicating that listing a species may be warranted, we are
required to promptly review the status of the species (status review).
For the status review to be complete and based on the best available
scientific and commercial information, we request information on the
Thorne's hairstreak butterfly from governmental agencies, Native
American Tribes, the scientific community, industry, and any other
interested parties. We seek information on:
(1) The species' biology, range, and population trends, including:
(a) Habitat requirements for feeding, breeding, and sheltering;
(b) Genetics and taxonomy;
[[Page 17063]]
(c) Historical and current range including distribution patterns;
(d) Historical and current population levels, and current and
projected trends; and
(e) Past and ongoing conservation measures for the species and/or
its habitat or both.
(2) The factors that are the basis for making a listing/delisting/
downlisting determination for a species under section 4(a) of the
Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et
seq.), which are:
(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.
(3) The historical and current status and distribution of the
Thorne's hairstreak butterfly, its biology and ecology, and ongoing
conservation measures for the species and its habitat in the United
States and Mexico.
(4) Information on management programs for the conservation of the
Thorne's hairstreak butterfly.
Please include sufficient information with your submission (such as
full references) to allow us to verify any scientific or commercial
information you include.
If, after the status review, we determine that listing the Thorne's
hairstreak butterfly is warranted, we intend to propose critical
habitat (see definition in section 3(5)(A) of the Act), in accordance
with section 4 of the Act, to the maximum extent prudent and
determinable at the time we propose to list the species. Therefore,
within the geographical range currently occupied by the Thorne's
hairstreak butterfly, we request data and information on:
(1) What may constitute ``physical or biological features essential
to the conservation of the species,''
(2) Where these features are currently found, and
(3) Whether any of these features may require special management
considerations or protection.
In addition, we request data and information on ``specific areas
outside the geographical area occupied by the species'' that are
``essential to the conservation of the species.'' Please provide
specific comments and information as to what, if any, critical habitat
you think we should propose for designation if the species is proposed
for listing, and why such habitat meets the requirements of section 4
of the Act.
Submissions merely stating support for or opposition to the action
under consideration without providing supporting information, although
noted, will not be considered in making a determination. Section
4(b)(1)(A) of the Act directs that determinations as to whether any
species is an endangered or threatened species must be made ``solely on
the basis of the best scientific and commercial data available.''
You may submit your information concerning this status review by
one of the methods listed in the ADDRESSES section. If you submit
information via https://www.regulations.gov, your entire submission--
including any personal identifying information--will be posted on the
website. If you submit a hardcopy that includes personal identifying
information, you may request at the top of your document that we
withhold this personal identifying information from public review.
However, we cannot guarantee that we will be able to do so. We will
post all hardcopy submissions on https://www.regulations.gov.
Information and supporting documentation that we received and used
in preparing this finding, will be available for you to review at
https://www.regulations.gov, or you may make an appointment during
normal business hours at the U.S. Fish and Wildlife Service, Carlsbad
Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Background
Section 4(b)(3)(A) of the Act requires that we make a finding on
whether a petition to list, delist, or reclassify a species presents
substantial scientific or commercial information indicating that the
petitioned action may be warranted. We are to base this finding on
information provided in the petition, supporting information submitted
with the petition, and information otherwise available in our files. To
the maximum extent practicable, we are to make this finding within 90
days of our receipt of the petition and publish our notice of the
finding promptly in the Federal Register.
Our standard for substantial scientific or commercial information
within the Code of Federal Regulations (CFR) with regard to a 90-day
petition finding is ``that amount of information that would lead a
reasonable person to believe that the measure proposed in the petition
may be warranted'' (50 CFR 424.14(b)). If we find that substantial
scientific or commercial information was presented, we are required to
promptly review the status of the species, which is subsequently
summarized in our 12-month finding.
Previous Federal Actions
On August 8, 2006, we published 90-day findings for both the
Thorne's hairstreak and the Hermes copper butterfly in the Federal
Register. The findings concluded that the petitions and information in
our files did not present substantial scientific or commercial
information indicating that listing Thorne's hairstreak (71 FR 44980)
or Hermes copper butterflies (71 FR 44966) was warranted. (For a
detailed history of Federal actions involving the Thorne's hairstreak
butterfly prior to the 2006 90-day finding, please see the August 8,
2006 Federal Register Notice (71 FR 44980)). On March 17, 2009, CBD and
David Hogan filed a complaint for declaratory and injunctive relief
challenging the Service's decision not to list the Thorne's hairstreak
butterfly and the Hermes copper butterfly as threatened or endangered
under the Act. In a settlement agreement dated October 23, 2009 (Case
No. 09-0533 S.D. Cal.), the Service agreed to submit new 90-day
petition findings to the Federal Register by April 2, 2010, for the
Thorne's hairstreak butterfly, and by May 13, 2010, for the Hermes
copper butterfly. As a part of the settlement agreement, we agreed to
evaluate the October 25, 2004 petition filed by David Hogan and CBD,
supporting information submitted with the petition, and information
available in the Service's files, including information that has become
available since the publication of the negative 90-day findings on
August 8, 2006. If the 90-day findings determine that listing may be
warranted, we agreed to submit a 12-month finding to the Federal
Register by March 4, 2011, for the Thorne's hairstreak butterfly, and
by April 15, 2011, for the Hermes copper butterfly.
This notice constitutes our 90-day finding on the petition to list
Thorne's hairstreak butterfly under section 4(b)(1)(A) of the Act. We
will publish the 90-day finding on the petition to list Hermes copper
butterfly in a future Federal Register document.
Species Information
Taxonomy
Thorne's hairstreak butterfly was first described by John Brown
(1983) based on a specimen collected by Fred Thorne in 1972. In this
description, Brown placed the new species in the Lycaenidae family with
the scientific name Mitoura thornei. The taxonomic ranking and
placement of Mitoura
[[Page 17064]]
thornei was evaluated in 1999 by the Committee on Scientific Names of
North American Butterflies and subsequently changed to a subspecies of
Callophrys gryneus (Faulkner and Klein 2005, p. 31). As a result of
this change, the species was renamed as Callophrys gryneus thornei. To
validate this nomenclature change, the Service contracted Dr. Richard
W. Van Bursick (2004) to review the Thorne's hairstreak butterfly's
taxonomic status. This review concurred with the Committee on
Scientific Names of North American Butterflies' (1999) decision and the
Service currently recognizes Thorne's hairstreak butterfly as the
subspecies Callophrys gryneus thornei. There has been significant
discussion and disagreement by species experts on the taxonomic
placement of this butterfly species (Faulkner and Klein 2005, p. 31),
resulting in our receipt of new information from a species expert that
disagrees with the previously cited taxonomic classification of
Thorne's hairstreak butterfly (Klein 2009, pers. comm.). Due to the
discrepancy over the taxonomic nomenclature of this species, we plan to
re-evaluate Van Buskirk's (2004) review of taxonomic status for
Thorne's hairstreak butterfly and will publish the results in the 12-
month finding.
The host plant for Thorne's hairstreak butterfly larvae is
Hesperocyparis forbesii (Tecate cypress). This species had been known
for some time in the literature as Cupressus forbesii. Cupressus
forbesii, and the rest of the Western Hemisphere taxa of Cupressus have
been segregated as Hesperocyparis based on phylogenetic comparisons
that support morphological evidence (Adams et al. 2009, pp. 160-185).
Hesperocyparis forbesii will be the name recognized for the species in
the upcoming revision of the Jepson Manual of the Flora of California.
This name will used throughout this and all future documents referring
to this species.
Species Status and Distribution
Thorne's hairstreak butterfly is endemic to San Diego County, and
more specifically found exclusively in the Otay Mountain area (Faulkner
and Klein 2005, p. 31). It is dependent on its larval host plant,
Hesperocyparis forbesii, to complete its lifecycle (Brown 1983), and is
the only plant known on which Thorne's hairstreak butterflies lay their
eggs. Adults lay their eggs on H. forbesii stems where the eggs mature,
subsequently hatch, and larvae feed until pupation occurs in the duff
and leaf litter at the base of the plant. Thorne's hairstreak
butterflies have two hatching or flight periods per year (termed
bivoltine): the first flight period occurs in late March to early April
and the second flight period occurs in September, which is thought to
be dependent on the presence of summer rains (Faulkner and Klein 2005,
p. 32). Adult Thorne's hairstreak butterflies are known to feed
throughout the chaparral ecosystem on the nectar of Eriogonum
fasciculatum (California buckwheat), Ceanothus tomentosus (Ramona
lilac), and Lotus scoparius (deerweed) in the vicinity of stands of H.
forbesii (Faulkner and Klein 2005, p. 33). We received new information
as a result of a recent study indicating that Asclepias fascicularis
(narrowleaf milkweed) is also used as an adult nectar source by
Thorne's hairstreak butterfly throughout the species' range (Lucas
2009, pers. comm.). Confirmed observations of Thorne's hairstreak
butterfly have been historically reported throughout the Otay Mountain
area and have been repeatedly reported from O'Neill Canyon, Little
Cedar Canyon, and Cedar Canyon, all of which are within the Otay
Mountain wilderness (Betzler et al. 2003, pp. 13-14; Martin 2004, pers.
comm.; Faulkner and Klein 2005, p. 32; Lucas 2009, unpublished data).
Habitat
Hesperocyparis forbesii, a species generally associated with
chaparral, is a serotinous- (not opening on maturity) or closed-coned
conifer. Typically,its cones do not open and disperse seed until after
fire, which nearly always results in the death of the parent tree
(Zedler 1977, p. 456). Cone production for H. forbesii begins around 10
years of age (Zedler 1977, p. 456). While Zedler (1977, p. 456)
asserted that maximum production per tree is not achieved until
individuals reach approximately 50 years of age, Dunn (1986, p. 371)
concluded that a maximum level of cones per square meter of the cypress
stand is attained at about 35 to 40 years of age. Hesperocyparis
forbesii's historical distribution on Otay Mountain was known to be
approximately 7,500 acres (ac) (3,035 hectares (ha)) (CNDDB 2003).
Hesperocyparis forbesii persistence may be impacted by wildfires in
the Otay Mountain area. Throughout the past 35 years, the Otay Mountain
area has been subject to multiple fires of various levels of severity
(Zedler 1977, p. 456; Keeley and Fotheringham 2003, pp. 242-243).
Service GIS files indicate that the 2003 Otay/Mine fire footprint
completely covered the known distribution of H. forbesii in the Otay
Mountain area followed by the 2007 Harris fire that burned a
substantial portion of this area again. Some researchers also
postulated that an increase in frequency of fires in the area may: (1)
Result in changing vegetation structure or type conversion (Zedler
1977, p. 457; Zedler et al. 1983, p. 817; Keeley and Fotheringham 2003,
pp. 243-244), and (2) lead to significant declines or possible
extinction of H. forbesii in the Otay Mountain area because adult H.
forbesii will not have the opportunity to reach an age where
reproductive output is high enough to sustain the population (Zedler
1977, p. 457). While Dunn (1985, p. 5) concluded that the Otay
population was not in ``immediate danger,'' he noted that ``an
increasing threat of development and its effects on fire frequency''
affected this area. Nonetheless, de Gouvenain and Ansary (2006, pp.
451-452) reported that the Otay Mountain, Tecate Peak, and Guatay
populations of H. forbesii ``appeared to be stable or potentially
increasing'' (i.e., the rate of population increase or [lgr] > 1).''
However, Markovchick-Nicholls (2007, p. 50) concluded that ``[m]odel
results utilizing available data and incorporating natural variation
suggest that Tecate cypress [in the United States] will decline under
most fire regime scenarios over the long-term, but that this trend may
be difficult to detect in the short-term.'' Results from a recent study
on the abundance of H. forbesii stands (individuals 3.3 ft (1 m) or
higher) indicate there are approximately 454 ac (184 ha) located
throughout the Otay Mountain area (Lucas 2009, unpublished data) and
other burned areas contain small (less than 3.3 ft (1 m)) individuals
that have sprouted since the 2003 and 2007 fires (Winchell, pers. obs.
2009). These surveys corroborated historical data (Betzler et al. 2003)
that the oldest stands occur in Little Cedar Canyon and the largest
stands occur in O'Neal Canyon (Lucas 2009, unpublished data); this
survey information indicates that these stands have survived after
repeated fire events. Additionally, Thorne's hairstreak butterfly has
been observed perching on H. forbesii and nectaring on other chaparral
plants during multiple survey periods between and following the 2003
and 2007 fires that occurred in the Otay Mountain area (Betzler et al.
2003, pp. 13-14; Martin 2004, pers. comm.; Faulkner and Klein 2005, p.
32; Lucas 2009, unpublished data).
For additional species information on Thorne's hairstreak
butterfly, please refer to our previous 90-day finding, which published
in the Federal Register on August 8, 2006 (71 FR 44980).
[[Page 17065]]
Evaluation of Information for this Finding
Section 4 of the Act (16 U.S.C. 1533), and its implementing
regulations in the Code of Federal Regulations (CFR) at 50 CFR 424, set
forth the procedures for adding species to the Federal Lists of
Endangered and Threatened Wildlife and Plants. A species may be
determined to be an endangered or threatened species due to one or more
of the five factors described in section 4(a)(1) of the Act: (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.
In making this 90-day finding, we evaluated whether information on
threats to Thorne's hairstreak butterfly, as presented in the 2004
petition and other information available in our files, is substantial,
thereby indicating that the petitioned action may be warranted. In the
sections that follow, we summarize information included in the 2004
petition and evaluate any new information in our files, including
information that has become available since the publication of the not-
substantial 90-day finding on August 8, 2006. For a detailed evaluation
of threats listed in the petition, please refer to the previous 90-day
finding that published in the Federal Register on August 8, 2006 (71 FR
44980).
A. The Present or Threatened Destruction, Modification, or Curtailment
of the Species' Habitat or Range
The petition, its appendices, and referenced documents discuss the
following threats that are grouped under Factor A: wildfire, prescribed
burns, grazing, vehicle access and recreation, and habitat
fragmentation.
Wildfire
Information Provided in the Petition
The petitioners assert that Thorne's hairstreak butterfly is
vulnerable to extinction from wildfire, which can cause direct
mortality of individual butterflies (see discussion under Factor E) and
indirect mortality resulting from a loss of the species' larval host
plant, Hesperocyparis forbesii. The petition further asserts that a
single fire may threaten a significant portion of Thorne's hairstreak
butterfly's range (such as the 2003 fire, as cited in Betzler et al.
2003, p. 13). Additionally, increased fire frequency throughout the
species' range may result in an increase in the abundance or an
expansion of highly flammable, invasive, nonnative plant species, or
vegetation type conversion and the replacement of chaparral ecosystems
with nonnative plant species, thereby impacting the habitat on which
Thorne's hairstreak butterfly depends (Keeley and Fotheringham 2003,
pp. 243-245; Brooks et al. 2004, pp. 677-688).
Evaluation of Information Provided in the Petition and Available in
Service Files
Distribution of Thorne's hairstreak butterfly is limited to the
Otay Mountain area (part of the San Ysidro Mountain range in southern
San Diego County, California) and is dependent on the presence of
Hesperocyparis forebesii, which is the butterfly's larval host plant
(Brown 1983, pp. 245-254). The current distribution of H. forbesii in
the Otay Mountain area encompasses 454 ac (183 ha) (Lucas 2009,
unpublished data); however, historical records indicate that H.
forbesii in the Otay Mountain area once covered approximately 7,500 ac
(3,035 ha) (CNDDB 2003). Of the current 454 ac (183 ha) of H. forbesii,
approximately 34.7 ac (14 ha) are privately owned, 7.6 ac (3 ha) are
owned by California Department of Fish and Game, and 5.5 ac (2.2 ha)
are owned by the City of Chula Vista. The remaining approximately 406
ac (164 ha) of H. forbesii habitat in the Otay Mountain area occurs
within the Bureau of Land Management (BLM) Otay Mountain Wilderness
(see Factor D for more information on the Otay Mountain Wilderness).
Confirmed observations of Thorne's hairstreak butterfly have been
reported throughout the Otay Mountain area, but primarily occur from
two canyons: Little Cedar Canyon and Cedar Canyon both within the Otay
Mountain Wilderness (Betzler et al. 2003, pp. 13-14). Thorne's
hairstreak butterfly is a narrow endemic species with historically
declining habitat throughout the Otay Mountain area (Brown 1983, pp.
245-254; BLM 2009(b), p. 3-59); Congedo and Williams 2009, p. 1).
Information in our files indicates that wildfires in 2003 and 2007
burned throughout the Hesperocyparis forbesii stands in the Otay
Mountain area, which are known to be occupied by Thorne's hairstreak
butterfly. The rapid reburning of this area (fire intervals less than
40 years) may have impacted mature H. forbesii by keeping them at a
growth stage where reproductive output is not high enough to sustain
the population of H. forbesii (de Gouvenain and Ansary 2006, pp. 447-
448; Markovchick-Nicholls 2007, p. 7); therefore, the availability of
larval habitat for Thorne's hairstreak butterfly may be reduced by
wildfires. It is also possible that replacement of other chaparral
species (i.e., nectar sources) may have occurred under this fire
regime, thereby removing nectar sources necessary to support Thorne's
hairstreak butterfly; however, we have no information to support the
petitioners' claim, and we will investigate this in our status review
of the species. It is likely that wildfires will occur within the range
of this species in the future. Therefore, we find the petition and
information in our files presents substantial information indicating
that listing Thorne's hairstreak butterfly may be warranted due to the
threat of short-return-interval wildfire.
Prescribed Burns
Information Provided in the Petition
The petitioners state that while prescribed burns do not appear to
be planned by BLM for the San Ysidro Mountain range, any that do occur
in the future could compound the threat of excessive fire to Thorne's
hairstreak butterflies and Hesperocyparis forbesii.
Evaluation of Information Provided in the Petition and Available in
Service Files
We did not find substantial information in the petition or in our
files to indicate prescribed burns by BLM in the San Ysidro Mountain
range may threaten Thorne's hairstreak butterfly. The species and its
larval plant host, Hesperocyparis forbesii, occur almost exclusively
(approximately 90 percent) in the Otay Mountain Wilderness (see also
Factor D). BLM's South Coast Resource Management Plan (South Coast RMP)
(BLM 1994) generally allows prescribed burns; however, the Otay
Mountain Wilderness has been managed under a policy of complete fire
suppression (Woychok 2006, pers. comm.). In the Cedar Canyon area, the
South Coast RMP states that BLM will not consider prescribed burns
until 2020 to minimize the risk of jeopardizing H. forbesii
regeneration after fires (BLM 1994, p. 21). Additionally, BLM is
currently drafting a revised South Coast RMP that includes no
prescribed burns and follows fire suppression practices until H.
forbesii returns to its historical fire cycle of 50 years (BLM 2009(b),
pp. 4-171-4-172). After 50 years without fire in a give H. forbesii
stand, BLM would allow prescribed burns up to 500 ac per year. However,
this new South Coast RMP is
[[Page 17066]]
in an early draft stage and is not currently being implemented by BLM.
The other locations in the Otay Mountain area that contain H. forbesii
stands (approximately 10 percent) receive protection under the City of
Chula Vista Subarea Plan or the County of San Diego Subarea Plan under
the Multiple Species Conservation Program (MSCP). These subarea plans
require the conservation of natural vegetation communities (including
H. forbesii stands), and states that ``a fire management program would
be needed for prevention of catastrophic fires and long-term
viability'' of both Thorne's hairstreak butterfly and its larval host
plant. Therefore, we find the petition and information in our files do
not present substantial information indicating that listing Thorne's
hairstreak butterfly may be warranted due to the threat of prescribed
burns. However, we will further investigate the potential threat of
prescribed burns in our status review for this species.
Grazing
Information Provided in the Petition
The petition states that grazing may harm Thorne's hairstreak
butterfly and its larval host plant, Hesperocyparis forbesii, if
grazing within the currently vacant Otay Grazing Allotment
(approximately 5,522 ac (2,235 ha) (BLM 2009(b), p. 3-116) located on
BLM lands on Otay Mountain) occurs in the future. The threat of grazing
as it relates to direct mortality of individual butterflies is
discussed under Factor E. The petitioners assert that the allotment is
being considered for renewed grazing in the future and that cattle
grazing will cause harm to the habitat (by trampling the larval host
and through soil modification) and increase the occurrence of nonnative
plants, thus leading to an increase in fire frequency, and resulting in
loss of Thorne's hairstreak butterfly habitat.
Evaluation of Information Provided in the Petition and Available in
Service Files
The petitioners state that the Otay Grazing Allotment is vacant.
Information in our files indicates the allotment is leased but has been
in a state of non-use since 2000 (BLM 2009(b), p. 3-120). The Otay
Grazing Allotment is completely contained within the Otay Mountain
Wilderness and encompasses suitable adult Thorne's hairstreak butterfly
habitat (i.e., the host plant and other chaparral plants, which
includes nectar sources for adults) (Lucas 2009, pers. comm.),
including approximately 16 percent (75.2 ac (30.4 ha)) of the
Hesperocyparis forbesii in the Otay Mountain area. The available adult
and larval habitat for Thorne's hairstreak butterfly is currently not
impacted by grazing and a large majority of the adult and larval
habitat would remain unaffected if grazing resumed in the Otay Grazing
Allotment in the future. Neither the petition nor other information in
our files presents substantial information indicating that listing
Thorne's hairstreak butterfly may be warranted due to the threat of
grazing. However, we will further investigate the potential threat of
grazing in our status review for this species.
Vehicle Access and Recreation
Information Provided in the Petition
The petitioners assert that vehicle access and recreation in the
San Ysidro Mountain range will likely lead to increased fire frequency.
Additionally, they state that certain roads were grandfathered into the
Otay Mountain Wilderness designation and generally allow unrestricted
public access to Thorne's hairstreak butterfly habitat.
Evaluation of Information Provided in the Petition and Available in
Service Files
The Otay Mountain Wilderness Area allows public access; however,
recreational use is considered light with no more than 1,000 visitor
use days per year (BLM 2009(b), p. 3-103). Visitors are encouraged to
be responsible and follow the BLM program called ``Leave No Trace,''
which minimizes impacts from human uses. Motorized vehicle use is not
permitted in the designated Wilderness Area with the exception of two
pre-existing roads, and off-highway vehicles are completely excluded
(BLM 2009(b), pp. 2-124-2-125). The majority of traffic through the
area is concentrated on a few small roads used by border patrol agents.
Border patrol vehicles may increase the risk of fire in this area,
although fires are expected to be immediately reported (BLM 2009(b), p.
2-151).
Although light recreational use and minimal traffic associated with
border patrol agents occurs in the Otay Mountain Wilderness, the
information available to us does not indicate that recreation and
vehicle use is a threat to Thorne's hairstreak butterfly. These two
pre-existing roads within the Otay Mountain Wilderness extend outside
of BLM property onto private lands; however, they are small, one-lane,
remote, dirt roads that only pass near stands of Hesperocyparis
forbesii and do not appear to be heavily used. We do not have
information to support the claim that vehicle access would increase the
fire frequency in the area. Additionally, we do not have information in
our files and the petitioners did not present information to indicate
that vehicle access and recreation are a threat to the species in the
Otay Mountain Wilderness or in privately-owned areas. Therefore, we
find the petition and information in our files do not present
substantial information indicating that listing Thorne's hairstreak
butterfly may be warranted due to the threat of vehicle access and
recreation. However, we will further investigate the potential threat
of recreation and vehicle access in our status review for this species.
Habitat Fragmentation
Information Provided in the Petition
The petitioners claim that both habitat fragmentation and habitat
degradation pose a substantial threat to Thorne's hairstreak butterfly
and its habitat through both habitat modification and fragmentation of
butterfly populations. The petitioners assert that the habitat has been
degraded and modified such that Thorne's hairstreak butterfly is unable
to locate suitable habitat, which will likely impact the species
throughout its geographical range. The impacts associated with Thorne's
hairstreak butterfly population fragmentation are assessed under Factor
E (see below).
Evaluation of Information Provided in the Petition and Available in
Service Files
We agree that habitat for Thorne's hairstreak butterfly appears to
have been fragmented or degraded by wildfire. The current distribution
of Hesperocyparis forbesii in the Otay Mountain area encompasses 454 ac
(183 ha) (Lucas 2009, unpublished data) and is distributed in patches
across the landscape; however, historical records indicate that H.
forbesii in the Otay Mountain area once covered approximately 7,500 ac
(3,035 ha). Information in our files indicates that H. forbesii and
other chaparral species are currently recovering after recent fires
(Congedo and Williams 2009, p. 1; Lucas 2009, pers. comm.); however, we
do not have information in our files that indicates whether the habitat
has been impacted in a manner that would inhibit recovery to historical
levels. We note that the amount of larval habitat has increased from
2004 to 2009 (Lucas 2009, unpublished data).
Zedler et al. (1983, pp. 809-818) describes vegetation type
conversion
[[Page 17067]]
(also considered a type of habitat fragmentation) within the Otay
Mountain area; however, information in our files describes recovering
H. forbesii habitat and availability of various suitable nectar sources
after the fires in 2003 and 2007, including one source that was
previously unknown (Lucas 2009, pers. comm.).
Additionally, the petition cites roads as a mechanism of habitat
fragmentation; however, roads are unlikely to cause habitat
fragmentation to an extent that would impact Thorne's hairstreak
butterfly population because the roads are small, one-lane, remote,
dirt roads with little traffic. The Otay Mountain Wilderness, managed
by the BLM, has only two main roads and a few other small roads that
allow motorized vehicles (off-highway vehicle use is excluded
throughout the Otay Mountain Wilderness); therefore, habitat
fragmentation resulting from roads would be very minimal.
In summary, we evaluated the petition and information in our files
and find that substantial information exists to indicate that listing
Thorne's hairstreak butterfly may be warranted due to the present or
threatened destruction, modification, or curtailment of the habitat or
range of the species due to the threat of wildfires and the possibility
that habitat fragmentation may be occurring as a result of wildfires.
We will further investigate the potential threat of habitat
fragmentation in our status review for this species.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Information Provided in the Petition
The petition does not present any information with respect to
Factor B.
Evaluation of Information Provided in the Petition and Available in
Service Files
The information in our files does not indicate any threat to
Thorne's hairstreak butterfly due to overutilization for commercial,
recreational, scientific, or education purposes. Therefore, we find
that the petition and information in our files do not provide
substantial information indicating listing Thorne's hairstreak
butterfly may be warranted due to the overutilization for commercial,
recreational, scientific, or education purposes. However, we will
further investigate the potential threat of overutilization for
commercial, recreational, scientific, or education purposes in our
status review for this species.
C. Disease or Predation
Disease
Information Provided in the Petition
The petition does not present any information concerning threats
from disease to Thorne's hairstreak butterfly.
Evaluation of Information Provided in the Petition and Available in
Service Files
We have no information in our files to indicate any threat from
disease to Thorne's hairstreak butterfly.
Predation
Information Provided in the Petition
The petitioners state that species experts (Klein (date not
provided), pers. comm.) suspect that birds, predatory insects,
parasitic insects, and spiders prey upon Thorne's hairstreak butterfly.
Additionally, the petitioners assert that the harmful effects of
otherwise normal predation or parasitism might be exacerbated by
population reduction from excessive fires.
Evaluation of Information Provided in the Petition and Available in
Service Files
Faulkner and Klein (2005, p. 34) state that birds may consume
Thorne's hairstreak larvae; however, we are not aware of any data to
support a theory of bird predation as a significant threat to Thorne's
hairstreak butterflies. Brachonid wasps, which are parasitic insects,
have been observed near the host plant, but there has been no
documentation of parasitism to Thorne's hairstreak butterflies
(Faulkner and Klein 2005, p. 34). The petitioners do not provide
information to support their claim that predation or parasitism may
exacerbate population reduction resulting from fires, nor do we have
any information in our files to support this claim.
Neither the petition nor our files present substantial information
that disease or predation pose significant threats to Thorne's
hairstreak butterfly. Therefore, we find that the petition and
information in our files do not provide substantial information
indicating that listing Thorne's hairstreak butterfly may be warranted
due to disease or predation. However, we will further investigate the
potential threat of disease and predation in our status review for this
species.
D. The Inadequacy of Existing Regulatory Mechanisms
The petition cites three regulatory mechanisms that may provide
some, but not adequate, Thorne's hairstreak butterfly conservation,
including:
(1) The Wilderness Act,
(2) BLM management activities, and
(3) The County of San Diego Subarea Plan under the Multiple
Species Conservation Program (MSCP).
Information Provided in the Petition
The petitioners make the following statements concerning Thorne's
hairstreak butterflies and the Wilderness Act, BLM management
activities, and the County of San Diego Subarea Plan:
(1) The Wilderness Act does not provide significant protection for
the species;
(2) BLM does not consider the species as ``sensitive'', so the
species is not afforded sensitive species' protections within the
agency's management plan (i.e., the South Coast RMP));
(3) BLM is not actively implementing conservation measures for the
species;
(4) BLM is not pro-actively managing the private lands they have
acquired; and
(5) Despite Thorne's hairstreak butterfly being recognized as a
``covered species'' under the County of San Diego Subarea Plan, that
Plan does not provide sufficient protection for the species.
Evaluation of Information Provided in the Petition and Available in
Service Files
Thorne's hairstreak butterfly larval habitat on Otay Mountain
occurs almost entirely (92 percent) on publicly owned property (BLM,
City of Chula Vista or California Department of Fish and Game). The
following regulatory mechanisms and management actions apply to these
public lands and protect Thorne's hairstreak butterfly and its habitat:
(1) The Otay Mountain Wilderness Act (1999) (Pub. L. 106-145) and
BLM management policies provide protection for the vast majority of
Thorne's hairstreak butterfly habitat. The Otay Mountain Wilderness Act
provides that the Otay Mountain designated wilderness area (i.e., Otay
Mountain Wilderness; 18,500 ac (7,486 ha)) will be managed in
accordance with the provisions of the Wilderness Act of 1964 (16 U.S.C.
1131 et seq.). The Wilderness Act of 1964, in turn, strictly limits use
of wilderness areas, imposing restrictions on vehicle use, new
developments, chainsaws, mountain bikes, leasing, and mining in order
to protect the natural habitats of the areas,
[[Page 17068]]
maintain species diversity, and enhance biological values. Finally, any
lands acquired within the Otay Mountain Wilderness boundaries become
part of the designated wilderness area and they are managed in
accordance with all provisions of the Wilderness Act and applicable
laws.
(2) Sensitive species, as defined by BLM, are those species that
are not already designated as Federal- or State-listed species and
occur on Bureau-administered lands for which BLM has the capability to
significantly affect their conservation status through management. This
BLM policy is intended to ensure that actions authorized, funded, or
carried out by the BLM do not contribute to the need for these species
to become listed as endangered or threatened under the Act (BLM
2009(b), p. 3-58). Currently, Thorne's hairstreak butterfly is not
considered a sensitive species by BLM; however, BLM is currently
collaborating with the Service to revise the South Coast RMP. In this
draft revised plan, Thorne's hairstreak butterfly and Hesperocyparis
forbesii are identified as sensitive species (BLM 2009(b), p. 3-59),
and the draft revised plan specifically states the management of these
species and their habitats are important because of their close
association and the importance of fire cycles to their continued
existence. Moreover, one of BLM's primary objectives in the draft
revised plan is improved fire management and collaboration with local
communities and agencies to prevent wildfires. Additionally, BLM
intends to write a more specific plan for the Otay Mountain Wilderness
that identifies management measures and actions that would benefit H.
forbesii (Schlachter 2006, pers. comm.; BLM 2009(a), p. 1). BLM's
future management plans appear to provide a significant amount of
conservation and management measures, but they are currently not being
implemented throughout the Otay Mountain Wilderness Area. As a result
of wildfires on Otay Mountain there have likely been increases in
nonnative species which increase fuels available for future fires.
Furthermore, although the current fire suppression policy dictates all
fires should be suppressed once ignited, this has not prevented recent
wildlfires from burning through large areas of Thorne's hairstreak
butterfly habitat. Therefore, it appears current regulations for
Thorne's hairstreak butterfly and its habitat are not adequate to
control the threat of increased wildfire frequency.
(3) The Memorandum of Understanding (MOU) on cooperation in
habitat conservation planning and management issued by BLM in 1994 in
conjunction with the development of the County of San Diego Subarea
Plan (BLM 1994, pp. 1-8) applies to the Otay Mountain Wilderness
because it falls entirely within the boundary of this subarea plan. The
MOU details BLM's commitment to manage its lands in a manner that
compliments the County of San Diego MSCP Subarea Plan, which in turn,
requires protection of Thorne's hairstreak butterfly's larval host
plant and local chaparral species used as nectar sources. Additionally,
the MOU states that private lands acquired by BLM will be evaluated for
inclusion within the designated wilderness area and if the lands do not
meet wilderness qualifications they would be included in the region's
habitat conservation system (BLM 1994, p. 3). Any existing conservation
plans will be considered when managing these newly acquired lands (BLM
1994, p. 3; BLM 2009(b), pp. 2-74, N-1-2).
The draft revised South Coast RMP (see discussion in (2) above) ,
which covers the Otay Mountain Wilderness, does provide conservation
measures for both Thorne's hairstreak butterfly and Hesperocyparis
forbesii. The plan specifically includes a goal of restoring fire
frequency to 50 years through fire prevention or suppression and
prescribed burns; once an area has not burned for 50 years the plan
allows for annual prescribed burning of up to 500 acres (202.3 ha) in
the Otay Mountain Wilderness (BLM 2009(b), pp. 4-171-4-172). BLM's
future management plans appear to provide conservation and management
measures to assist with various threats to Thorne's hairstreak
butterfly and its habitat, but they are currently not being implemented
throughout the Otay Mountain Wilderness Area; therefore, it appears
that current regulations for Thorne's hairstreak butterfly and its
habitat are not adequate to control potential threats to this species,
including the threat of increased wildfire frequency.
(4) Approximately 48 ac (19 ha) of Hesperocyparis forbesii habitat
fall under the MSCP, which strives for fire management and prevention
to restore the previous 25-year fire cycle and states that ``a fire
management program would be needed for prevention of catastrophic fires
and long-term viability of its host plant.'' This shorter frequency of
fire may have an impact on adult H. forbesii because they will not have
the opportunity to reach an age (40 or more years) where reproductive
output is high enough to sustain the population (de Gouvenain and
Ansary 2006, pp. 447-448; Markovchick-Nicholls 2007, p. 7). Therefore,
the fire management and prevention policies of the MSCP which strive to
restore a 25 year fire cycle, may be inadequate to control the threat
of wildfire to this species.
There appear to be a variety of future management actions that BLM
couldimplement which may provide protection to Thorne's hairstreak
butterfly and its habitat; however, current existing regulatory
mechanisms by BLM and MSCP do not appear to be adequate to provide
protection for Thorne's hairstreak butterfly or its habitat from the
threat of increased wildfire frequency. Therefore, after our evaluation
of the petition and information in our files, we find that substantial
information exists to indicate that listing Thorne's hairstreak
butterfly may be warranted due to the inadequacy of existing regulatory
mechanisms.
E. Other Natural or Manmade Factors Affecting the Species' Continued
Existence
The petition, its appendices, and referenced documents discuss the
following threats that are grouped under Factor E: wildfire, grazing,
population fragmentation, vulnerability of small and isolated
populations, and global climate change.
Wildfire
Information Provided in the Petition
The petitioners state that Thorne's hairstreak butterfly cannot
escape fire. They stated that: (1) Pupae and larvae are likely killed
when fire burns Hesperocyparis forbesii stands and nearby chaparral;
(2) adults are likely killed by fire due to their habit of remaining
close to their host plant; and (3) adults are likely outpaced by an
approaching fire. The petition claims excessive fires over the last
several decades have reduced Thorne's hairstreak butterfly population
numbers and disrupted metapopulation dynamics and stability.
Evaluation of Information Provided in the Petition and Available in
Service Files
We agree that the majority of Thorne's hairstreak butterfly
individuals are likely killed when a fire passes through an occupied
area. Moreover, researchers questioned the persistence of Thorne's
hairstreak butterfly after the 2003 Otay/Mine fire because the fire
footprint appeared to cover all areas known to be occupied by the
species (IBAERT 2003, pp. 219-220; Betzler et al. 2003, p. 13).
Although, adult Thorne's hairstreak butterflies were documented from
four
[[Page 17069]]
unburned Hesperocyparis forbesii stands after the 2003 fire on the
southwest slope of the Otay Mountain (Martin 2004, pers. comm.),
surveyors in 2004 visiting the burned areas occupied prior to the 2003
fire, found evidence of new host plant growth but no adult Thorne's
hairstreak butterflies (Faulkner and Klein 2005, pp. 32). This is
likely due to the lack of available larval host plants and nectar
sources on which Thorne's hairstreak butterfly relies one year after
the fire.
Researchers have postulated that Thorne's hairstreak butterflies
require mature host plants for reproduction (Faulkner and Klein 2005,
p. 32); however, Thorne's hairstreak butterflies were observed in 2009
perching and feeding within re-growth areas burned in the 2003 and 2007
fires (Lucas 2009, pers. comm.). These observations in recently burned
(younger) stands of H. forbesii support the theory that Thorne's
hairstreak butterflies do not strictly require mature or adult trees as
host plants.
Even with some post-fire adult observations, it is likely the
majority of Thorne's hairstreak butterflies killed when habitat burns
and populations are further adversely impacted by frequently recurring
fires. Therefore, we find that the petition and information in our
files do provide substantial information to indicate that listing
Thorne's hairstreak butterfly may be warranted due to direct mortality
from wildfire.
Grazing
Information Provided in the Petition
The petitioners assert that grazing practices may lead to trampling
of eggs and larvae of Thorne's hairstreak butterfly.
Evaluation of Information Provided in the Petition and Available in
Service Files
The Otay Grazing Allotment, which is the only place in the current
range of the species that is grazed, is completely contained within the
Otay Mountain Wilderness and has not been grazed since 2000 (Doran
2006, pers. comm.; BLM 2009(b), p. 3-120). Information in our files
indicate that approximately 84 percent (378 ac (153 ha)) of the
Hesperocyparis forbesii within the Otay Mountain area are outside of
the Otay Grazing Allotment. The majority of the available habitat for
Thorne's hairstreak butterfly is currently not affected by grazing
(i.e., vegetation conditions are not favorable for grazing), and would
not be affected by grazing within the Otay Grazing Allotment should
grazing in the allotment resume in the future. Therefore, we find that
the petition and information in our files do not provide substantial
information to indicate that listing Thorne's hairstreak butterfly may
be warranted due to mortality from grazing. However, we will further
investigate in our status review for this species the potential threat
of trampling mortality from grazing and the potential impact that
grazing could have if it occurs in the future.
Population Fragmentation
Information Provided in the Petition
The petitioners state that fragmentation of Thorne's hairstreak
butterfly populations through fire, habitat type conversion, and roads
poses a significant threat to the species. The petitioners claim
habitat fragmentation reduces the area of Thorne's hairstreak butterfly
habitat and thereby threatens the species by isolating populations from
one another. The petitioners also claim that because Thorne's
hairstreak butterflies are habitat specialists, they have a higher risk
of extinction due to population fragmentation than a habitat
generalist. Additionally, the petitioners claim that habitat
fragmentation expands edge habitat, resulting in further stress on
fragmented or small populations, leading to isolation effects on the
population.
Evaluation of Information Provided in the Petition and Available in
Service Files
The petition describes the Thorne's hairstreak butterfly population
as fragmented as a result of habitat fragmentation. Hesperocyparis
forbesii and associated chaparral habitat has been disturbed by
wildfire; however, this habitat is recovering and Thorne's hairstreak
butterflies continue to occur throughout the burned area (Martin 2004,
pers. comm.; Faulkner and Klein 2005, pp. 32-33; Congedo and Williams
2009, p. 1; Lucas 2009, pers. comm.). Even though movement dynamics
have not been completely determined, information in our files indicates
Thorne's hairstreak butterfly is capable of re-colonizing and utilizing
immature H. forbesii stands in recently burned areas (Martin 2004,
pers. comm.; Faulkner and Klein 2005, p. 32; Lucas 2009, pers. comm.).
New information indicating that Asclepias fascicularis, a previously
unknown nectar source (Lucas 2009, pers. comm.), is used by Thorne's
hairstreak butterfly indicate that the butterfly's habitat requirements
may not be as specialized as previously thought.
The petition states that individuals have been observed nectaring
0.25 mile (0.40 kilometer) away from their host plant, which suggests
that individual butterflies are capable of moving at least this far to
find suitable habitats or mates. However, information in our files
indicates that the H. forbesii stands are patchily distributed and
separated by distances greater than 0.25 mile (0.40 kilometer), which
may contribute to population fragmentation. As a result of this
information, we find that the petition and information in our files
provides substantial information indicating listing Thorne's hairstreak
butterfly may be warranted due to population fragmentation. We intend
to further investigate and attempt to distinguish between habitat
fragmentation and population fragmentation in our status review of the
species.
Vulnerability of Small and Isolated Populations
Information Provided in the Petition
The petitioners assert that endemic taxa such as Thorne's
hairstreak butterfly are considered more prone to extinction than
widespread species due to their restricted geographical range.
According to the petition, the common factors that increase the
vulnerability of small and isolated populations to extinction are
demographic fluctuations, environmental stochasticity (random events),
and reduced genetic diversity.
Evaluation of Information Provided in the Petition and Available in
Service Files
The fact that a species is characterized by populations that are
few in number, small in size, or isolated does not necessarily mean the
species is threatened. Typically, it is the combination of small size
and number of populations and isolation of small populations in
conjunction with other threats (such as the present or threatened
destruction, modification, or curtailment of the species' habitat or
range) that may pose a threat to a species. Thorne's hairstreak
butterfly has always been endemic the Otay Mountains (Brown 1983;
Beztler et al. 2003; Faulkner and Klein 2005). If occupied habitat is
temporarily fragmented by fire, a fluctuation in Thorne's hairstreak
butterfly numbers could make small populations more vulnerable to
stochastic events. Small populations and the isolation of populations
from one another could also subject Thorne's hairstreak butterfly to
genetic drift and restrict gene flow that may decrease genetic
variability over
[[Page 17070]]
time and could adversely affect the species' viability (Allee 1931, pp.
12-37; Stephens et al. 1999, pp. 185-190; Dennis 2002, pp. 389-401).
Surveys conducted in 2009 (Lucas 2009, unpublished data) conclude that
Thorne's hairstreak butterflies are still present in the H. forbesii
stands on Otay Mountain. We have no quantitative survey information on
population numbers, but historical larval habitat has been reduced from
7,500 ac (3,035 ha) to approximately 454 ac (see ``Habitat'' section
above for more information). Since Thorne's hairstreak butterfly is
dependent on H. forbssi to complete its lifecycle, available larval
habitat is a proxy for population size. With this large reduction in
available larval habitat we believe that the species' population
distribution have been significantly reduced relative to historical
levels resulting in an increased risk of extinction due to stochastic
events such as wildfire. Therefore, we find that the petition and
information in our files do provide substantial information indicating
that listing Thorne's hairstreak butterfly may be warranted due to
restricted geographic range.
Global Climate Change
Information Provided in the Petition
The petitioners assert that butterflies (in general) are threatened
by global climate change and are sensitive to small changes in
microclimates, such as fluctuations in moisture, temperature, or
sunlight. According to the petition, studies of Edith's checkerspot
butterfly (Euphydryas editha) have verified speculation that whole
ecosystems may move northward or shift in elevation as the Earth's
climate warms (Parmesan and Galbraith 2004, p. 9).
Evaluation of Information Provided in the Petition and Available in
Service Files
We recognize recent evaluations by Parmesan and Galbraith (2004,
pp. 1-2, 29-33) that indicate whole ecosystems may be shifting
northward and upward in elevation, or are otherwise being altered by
differing climate tolerance among species within a community.
Parmesan's review (2006, pp. 637, 648-649, 653) indicates range-
restricted mountaintop species (such as Thorne's hairstreak butterfly)
typically experience range retractions. Additionally, we recognize that
climate change is likely to cause changes in the arrangement of
occupied habitat patches. Current climate change predictions for
terrestrial areas in the Northern Hemisphere indicate warmer air
temperatures, more intense precipitation events, and increased summer
continental drying (Field et al. 1999, pp. 1-3; Hayhoe et al. 2004, p.
12422; Cayan et al. 2005, p. 6; Intergovernmental Panel on Climate
Change 2007, p. 11). However, predictions of climatic conditions for
smaller subregions such as California remain uncertain. It is unknown
at this time if climate change in California will result in a warmer
trend with localized drying, higher precipitation events, or other
effects. Because, the information currently available on the effects of
global climate change and microhabitat changes, such as increasing
temperatures or moisture, does not make sufficiently precise estimates
of the magnitude of the effects, we are unable to determine what
impacts to Thorne's hairstreak butterfly may occur. Given this
uncertainty, we find that the petition and information in our files do
not provide substantial information to indicate that listing Thorne's
hairstreak butterfly may be warranted do to global climate change. We
will further investigate this potential threat to Thorne's hairstreak
butterfly in our status review of the species.
In summary, we find that the petition and information in our files
do provide substantial information indicating that listing Thorne's
hairstreak butterfly may be warranted due to other natural or manmade
factors affecting the species' continued existence. Specifically, we
find that the effects of wildfire on individuals, population
fragmentation, and restricted geographic range+may pose significant
threats to the species.
Finding
On the basis of our determination under section 4(b)(3)(A) of the
Act, we have determined that the petition presents substantial
scientific or commercial information indicating that listing Thorne's
hairstreak butterfly may be warranted. This finding is based on
information provided under Factor A (present or threatened destruction,
modification, or curtailment of the species' habitat or range), Factor
D (the inadequacy of existing regulatory mechanisms) and Factor E
(other natural or manmade factors affecting the species' continued
existence). Because we have found that the petition presents
substantial information indicating that listing Thorne's hairstreak
butterfly may be warranted, we are initiating a status review to
determine whether listing Thorne's hairstreak butterfly under the Act
is warranted.
The ``substantial information'' standard for a 90-day finding
differs from the Act's ``best scientific and commercial data'' standard
that applies to a status review to determine whether a petitioned
action is warranted. A 90-day finding does not constitute a status
review under the Act. In a 12-month finding, we will determine whether
a petitioned action is warranted after we have completed a thorough
status review of the species, which is conducted following a
substantial 90-day finding. Because the Act's standards for 90-day and
12-month findings are different, as described above, a substantial 90-
day finding does not mean that the 12-month finding will result in a
warranted finding.
The petitioners request that we designate critical habitat for this
species. If we determine in our 12-month finding that listing Thorne's
hairstreak butterfly is warranted, we will address the designation of
critical habitat at the time of the proposed rulemaking. The proposed
rulemaking may be published concurrently with the 12-month finding or
at a later date.
References Cited
A complete list of references cited is available on the Internet at
https://www.regulations.gov and upon request from the Carlsbad Fish and
Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Author
The primary authors of this notice are staff members of the
Carlsbad Fish and Wildlife Office (see FOR FURTHER INFORMATION
CONTACT).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
Dated: March 26, 2010.
Jeffrey L. Underwood,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010-7547 Filed 4-2-10; 8:45 am]
BILLING CODE 4310-55-S
