Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Unsilvered Fritillary Butterfly as Threatened or Endangered, 10310-10319 [2011-4037]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 37 (Thursday, February 24, 2011)]
[Proposed Rules]
[Pages 10310-10319]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-4037]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2010-0078; MO 92210-0-0008 B2]


Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the Unsilvered Fritillary Butterfly as Threatened or 
Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service, announce a 90-day 
finding on a petition to list the unsilvered fritillary butterfly 
(Speyeria adiaste) as threatened or endangered under the Endangered 
Species Act of 1973 (Act), as amended, and designate critical habitat. 
Based on our review, we find that the petition does not present 
substantial scientific or commercial information indicating that 
listing the unsilvered fritillary may be warranted. Therefore, we are 
not initiating a status review in response to this petition. We ask the 
public to submit to us any new information that becomes available 
concerning the status of, or threats to, the unsilvered fritillary or 
its habitat at any time.

DATES: The finding announced in this document was made on February 24, 
2011.

ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket Number FWS-R8-ES-2010-0078 and at https://www.fws.gov/ventura. Supporting documentation we used in preparing this 
finding is available for public inspection, by appointment, during 
normal business hours at the U.S. Fish and Wildlife Service, Ventura 
Fish and Wildlife Office, 2493 Portola Road, Suite B, Ventura, CA 
93003; telephone 805-644-1766; facsimile 805-644-3958. Please submit 
any new information, materials, comments, or questions concerning this 
finding to the above street address.

FOR FURTHER INFORMATION CONTACT: Michael McCrary, Listing and Recovery 
Coordinator for Wildlife, Ventura Fish and Wildlife Office (see 
ADDRESSES), by telephone 805-644-1766, or by facsimile 805-644-3958. If 
you use a telecommunications device for the deaf (TDD), call the 
Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

[[Page 10311]]

Background

    Section 4(b)(3)(A) of the Act (16 U.S.C. 1531 et seq.) 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 conduct a species status review, which we subsequently 
summarize in our 12-month finding.

Petition History

    On January 12, 2010, we received a petition, dated January 6, 2010, 
from WildEarth Guardians, requesting that the unsilvered fritillary 
butterfly be listed as threatened or endangered and critical habitat be 
designated under the Act. The petition clearly identified itself as 
such and included the requisite identification information for the 
petitioner, as required by 50 CFR 424.14(a). In a February 10, 2010, 
letter to the petitioner, we acknowledged receipt of the petition and 
stated that we had secured the funding to conduct the initial finding 
as to whether the petition contains substantial information indicating 
that the action may be warranted. We also stated that we determined 
that issuing an emergency regulation temporarily listing the species 
under section 4(b)(7) of the Act was not warranted. This finding 
addresses the petition.

Previous Federal Actions

    On January 6, 1992, the Service received a petition from Drs. 
Dennis Murphy and Alan Launer of the Stanford University Center for 
Conservation Biology to list Speyeria adiaste adiaste, one of the three 
subspecies of unsilvered fritillary, as an endangered or threatened 
species. In our November 22, 1994, 90-day petition finding (59 FR 
28741), we determined that, although the S. adiaste adiaste may be 
declining, existing information was not available to estimate the 
extent or rate of changes in habitat or population levels. We stated 
that further surveys were needed to adequately assess its distribution 
and population status, and beyond the information described above, the 
petitioner presented little else on the status of the animal. 
Therefore, the Service determined that the petition did not present 
substantial information that the requested action may be warranted.

Species Information

    The unsilvered fritillary is a medium-sized, brush-footed butterfly 
limited to the central coast region of California (WildEarth Guardians 
2010, p. 1). This butterfly has a 2-2.38-inch (5-6.1-centimeter (cm)) 
wingspan. The upper side of adult males is pale reddish-tan to bright 
red and the undersides are pale yellow to gray; females are larger and 
paler than males. The unsilvered fritillary has small, scattered, dark 
markings and a bold postmedian line. This species also has unsilvered 
hindwing spots that slightly contrast with background coloring, unlike 
the silvered markings of most Speyeria species (Butterflies and Moths 
of North America (BMNA) 2009, p. 1). Adults lay single eggs on fallen 
leaves and twigs near violets (Viola spp.). Caterpillars hibernate 
without feeding, but feed on violet leaves when they emerge in spring 
(NatureServe 2009, not paginated; BMNA 2009, p. 1). Adults have been 
observed feeding on the flowers of native and nonnative thistles 
(family Asteraceae) and California buckeye (Aesculus californica) 
(NatureServe 2009, not paginated). The unsilvered fritillary breeds 
once per year, with its adult butterfly stage occurring in June through 
July (flight period) (BMNA 2009, p. 1).
    The unsilvered fritillary inhabits openings in conifer and redwood 
forests, as well as oak woodlands, chaparral, and grassy slopes (BMNA 
2009, p. 2). Brittnacher et al. (1978, p. 200) considered it a xeric 
(adapted to an extremely dry habitat) Speyeria species that occurred in 
summer-dry locations.
    Violets are the only known host plants for Speyeria, including the 
unsilvered fritillary, and the distribution of these plants limits the 
extent of available habitat the species can occupy (Brittnacher 1978, 
p. 199). Mattoon et al. (1971) (in Brittnacher et al. 1978, p. 199) 
found that all the North American violets they tested can adequately 
support larval growth, although some European ornamentals, such as 
sweet violet (Viola odorata), are toxic to most Speyeria species.
    The petition states that there are 16 species in the Speyeria genus 
(WildEarth Guardians 2010, p. 4). Brittnacher et al. (1978, p. 199) 
state that there are at least 14 closely related Speyeria species, 10 
of which occur in California. In the draft recovery plan for the 
Behren's silverspot (S. zerene behrensii), the Service (2003, p. 3) 
stated that the genus Speyeria is a member of a complex group of 10 
species, having a polytypic (i.e., having many forms) population 
structure, with over 100 geographic subspecies. There are three 
recognized subspecies of the unsilvered fritillary, Speyeria adiaste 
adiaste (adiaste subspecies), S. a. clemencei (clemencei subspecies), 
and S. a. atossa (atossa subspecies) (NatureServe 2009, not paginated); 
however, as discussed below, the atossa subspecies is considered 
extinct.
    The historic range of the unsilvered fritillary covered much of the 
central and southern coastal region of California, extending from San 
Mateo County in the north to Los Angeles and Kern Counties in the south 
(BMNA 2009, p. 2). However, the current range is much smaller because 
the atossa subspecies is considered extinct (BMNA 2009, p. 2). 
Historically, the atossa subspecies was widely distributed in the 
Tehachapi Mountains, Tejon Mountains, and Mount Pinos region of Los 
Angeles and Kern Counties (Bruyea 2003, not paginated), living in open 
grasslands where violets, such as the pine violet (Viola purpurea), 
were abundant (Comstock 1927 in Hammond and McCorkle 1983, p. 220). The 
last known observations of the atossa subspecies occurred in 1959 just 
south of the town of Tehachapi and near Mount Pinos (Emmel and Emmel 
1973 in Bruyea 2003, not paginated).
    The two extant unsilvered fritillary subspecies occur in the 
central coast region of California from Santa Cruz County in the north 
to San Luis Obispo County in the south. The petition states that the 
adiaste subspecies is limited to the higher elevations of the Santa 
Cruz Mountains in San Mateo, Santa Cruz, and Santa Clara Counties 
(WildEarth Guardians 2010, p. 5). The clemencei subspecies has a more 
extensive range (BMNA 2009, p. 2), and the petition states that it 
occurs in the Santa Lucia Mountains in Monterey and San Luis Obispo 
Counties (WildEarth Guardians 2010, p. 5). The petition states that the 
unsilvered fritillary is distributed spottily within this range 
(WildEarth Guardians 2010, p. 6); however, the petition does not 
provide any other data on its abundance or distribution.

[[Page 10312]]

    The California Natural Diversity Database (CNDDB) (2010, not 
paginated) has only two records for the S. a. adiaste. One location is 
in Big Basin Redwoods State Park in Santa Cruz County, which is 
specifically discussed in the petition. The second location is on 
private land on the border between Santa Clara and Santa Cruz Counties. 
There are no records of S. a. clemencei in the CNDDB.
    NatureServe is cited frequently throughout the petition to support 
the assertion that the unsilvered fritillary should be listed under the 
Act. NatureServe is a nonprofit conservation organization that collects 
and manages data about the status and distribution of species and 
ecosystems of conservation concern and makes that information available 
to guide conservation, land-use planning, and natural resource 
management (NatureServe Web site 2009). As part of this service, 
NatureServe assesses and ranks the conservation status of species on a 
scale ranging from a ``conservation status rank'' of critically 
imperiled (1) to demonstrably secure (5). NatureServe ranks the 
unsilvered fritillary as G1G2, rounded to G1, ``critically imperiled,'' 
meaning the species is at high risk of extinction due to extreme rarity 
or to a limited range. However, NatureServe states that more 
information on abundance and number of occurrences and metapopulation 
dynamics of the species would be necessary to further refine its rank. 
NatureServe indicates that the long-term trend for the species has been 
a large-to-substantial decline (50 to 90 percent). However, NatureServe 
does not indicate whether the range of the species has declined or the 
abundance of the species has declined or both, although it does note 
that there is not enough information to determine the abundance of the 
species. The loss of the atossa subspecies represents a large decline 
in the range of the species, but does not necessarily reflect the 
status of the adiaste or clemencei subspecies. Although NatureServe 
states that there is not enough information to determine the number of 
occurrences of the species, it estimates the number of occurrences at 
1-20. NatureServe also ranks the three subspecies individually: S. a. 
adiaste is ranked as T1, critically imperiled in California; S. a. 
clemencei is ranked as T1T2, similar to the full species' rank of G1G2; 
and S. a. atossa is ranked as TX because it is presumed extinct. 
NatureServe (2009) states that populations of the adiaste subspecies 
``seem to have declined,'' but does not provide any information to 
support this observation. It should also be noted that NatureServe 
indicates on its Web site that conservation status ranks are neither a 
recommendation by the organization, nor an indication that a species 
requires legal status to assure its survival (NatureServe 2008, not 
paginated) and, in our view, should not be the sole basis for any 
decisions.
    Furthermore, the CNDDB includes S. a. adiaste on its species-at-
risk list, but the other two subspecies are not included. Similarly, 
the California Wildlife Action Plan includes S. a. adiaste as a species 
at risk in the central coast region based on the CNDDB classification.
    Although the petition did not provide any information on the 
results of any surveys that may have been conducted to determine the 
status of the atossa subspecies, the information available at this time 
indicates that the atossa subspecies is considered extinct. We also 
agree with the petitioner and other organizations, including 
NatureServe, that the range of the remaining extant subspecies of the 
unsilvered fritillary is limited to the central coast of California. 
However, the range of the species as described in both the petition and 
by NatureServe includes at least the mountainous portions of five 
counties. Although only a portion of this area is suitable habitat for 
the species, the petition did not provide information on either the 
distribution of the species or on the extent or distribution of its 
habitat; information on either or both could be used to refine the 
range of the species beyond what is described in the petition. The 
petition also did not present any information that would indicate that 
the ranges of the remaining two subspecies have been reduced. Nor did 
the petition present any information on either the number of 
populations or overall abundance of the two subspecies, or any changes 
in these. The classification of the unsilvered fritillary as being 
critically imperiled by NatureServe is apparently based on the loss of 
the atossa subspecies and the limited range of the two extant 
subspecies, rather than information on their past or present 
distribution and abundance. Therefore, there is no information that 
shows that the range of the two remaining subspecies has been reduced 
or that the number of populations or abundance of either of them has 
declined or is declining.

Evaluation of Information for This Finding

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations at 50 CFR part 424 set forth the procedures for adding a 
species to, or removing a species from, 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 
regarding threats to the unsilvered fritillary, as presented in the 
petition and other information available in our files, is substantial, 
thereby indicating that the petitioned action may be warranted. Our 
evaluation of this information is presented below.
    It is the overall position of the petition that, of the three 
subspecies of the unsilvered fritillary, Speyeria adiaste atossa is 
considered extinct, S. a. adiaste is limited in range and declining, 
and S. a. clemencei has a more extensive range but faces multiple 
threats, and, therefore, the species in its entirety faces extinction 
or endangerment.
    The petition states that the unsilvered fritillary has vanished 
from much of its range and asserts that this is due to human 
activities, including habitat loss and degradation due to burgeoning 
human populations, with resultant urban and suburban sprawl; increasing 
agriculture; extensive livestock grazing; off-road vehicle use; and 
other adverse land uses. The petition also asserts that climate change 
has taken and will take its toll through altered fire regimes, more 
severe and frequent droughts, and shifts in native plant distribution 
(WildEarth Guardians 2010, p. 12). The petition states that the Service 
should consider whether these threats intersect and act 
synergistically, thereby increasing the likelihood of extinction or 
endangerment of the unsilvered fritillary in the foreseeable future 
(WildEarth Guardians 2010, p. 16).
    Additionally, the petition states that the Service should consider 
how the suite of threats identified for four Federally listed Speyeria, 
the Behren's silverspot (Speyeria z. behrensii), the Oregon silverspot 
(S. z. hippolyta), the Myrtle's silverspot (S. z. myrtleae), and the 
Callippe silverspot (S. callippe callippe), might likewise threaten the

[[Page 10313]]

unsilvered fritillary (WildEarth Guardians 2010, p. 11).
    The endangered Behren's silverspot occurs at a single location near 
Point Arena, Mendocino County, California (Service 2003, p. iii). 
Threats identified in the recovery plan for this taxon are: Invasion by 
nonnative species, natural succession, fire suppression, residential 
development, and overcollection (Service 2003, pp. 12-16).
    The threatened Oregon silverspot occurs at disjunct sites near the 
Pacific coast from Del Norte County, California, north to Long Beach 
Peninsula, Washington. Threats identified in the recovery plan for this 
taxon are: Invasion by nonnative species, fire suppression, land 
development, off-road vehicles, livestock grazing, erosion, roadkill, 
insecticides, and overcollection (Service 2001, pp. 18-20).
    When listed, the endangered Myrtle's silverspot occurred in four 
areas in western Marin and southwestern Sonoma Counties, California, 
and the distribution and range have not significantly changed since 
listing in 1992 (Service 2009, p. 5). Threats identified in the 
recovery plan for this taxon are: Invasion by nonnative plants, loss of 
habitat from commercial and residential development, recreation, 
livestock grazing, agriculture, and over-collection (Service 1998, pp. 
59-60).
    The endangered Callippe silverspot occurs at San Bruno Mountain in 
San Mateo County and at Cordelia Hills in Sonoma County, California 
(Service 2009, p. 5). Threats identified in the listing rule for this 
taxon are: Habitat degradation due to human activities, off-road 
vehicles, invasion by nonnative plants, livestock grazing, and over-
collection (December 5, 1997, 62 FR 64306, pp. 64311-64312).
    The five factors discussed below are pertinent only in cases where 
the organism being proposed for listing may be a listable entity as 
defined by section 3(16) of the Act and is extant in the wild. The 
petition and its supporting information and information in our files 
indicate that the atossa subspecies is considered extinct. Because the 
atossa subspecies is considered extinct, the five factors are not 
analyzed for atossa. Therefore, the five factors are analyzed for the 
species of the unsilvered fritillary as a whole and for each of the two 
extant subspecies (adiaste and clemencei).

A. The Present or Threatened Destruction, Modification, or Curtailment 
of its Habitat or Range

    The petition asserts that development, fire suppression, widespread 
fires, agriculture, overgrazing, and exotic vegetation are causing the 
loss or degradation of the unsilvered fritillary's habitat (WildEarth 
Guardians 2010, p. 8). Moreover, the petition claims that the 
extirpations and decline of the unsilvered fritillary indicate severe 
degradation of its habitat, and these activities are pushing this 
species' Central coast grassland and woodland ecosystems toward 
collapse (WildEarth Guardians 2010, pp. 7-8). The petition states that 
NatureServe (2009, not paginated) estimates that the unsilvered 
fritillary has undergone a large-to-substantial decline, on the order 
of 50 to 90 percent (WildEarth Guardians 2010, p. 7).
    The petition also lists off-road vehicles as a threat to the 
unsilvered fritillary (WildEarth Guardians 2010, p. 9); however, it 
does not include any other information on either the operation of off-
road vehicles in relation to unsilvered butterfly populations or the 
habitat of the species.
Development: Information in the Petition
    As described in the petition, the various species of Speyeria 
butterflies are sensitive to human disturbance, and four species of 
Speyeria butterflies are listed as either threatened or endangered 
(WildEarth Guardians 2010, p. 11). Hammond and McCorkle (1983, p. 218) 
analyzed the general problem of declining Speyeria butterfly 
populations due to human-induced environmental disturbances and 
concluded that the fritillary butterflies of the genus Speyeria and 
their larval food plants, violets, are among the most sensitive 
organisms in native ecosystems, and are among the first to be 
exterminated as a result of widespread human disturbance.
    Human disturbance has been particularly destructive to native 
ecological communities along the West Coast, and many forms of Speyeria 
have become extinct or are threatened with extinction in this region 
(Hammond and McCorkle 1983, p. 220). One example of this is the atossa 
subspecies, which, as mentioned earlier, is considered extinct. The 
atossa subspecies was once widely distributed and extremely abundant in 
the Sierra Madre, Tejon, and Tehachapi Mountains of southern 
California, where it occurred in open grasslands where violets, such as 
the pine violet (Viola purpurea), were abundant (Comstock 1927, in 
Hammond and McCorkle 1983, p. 220). According to Emmel and Emmel (1973, 
in Hammond and McCorkle 1983, p. 220), this subspecies is probably 
extinct today, with the last known specimen collected in 1959. Although 
the actual causes of the atossa subspecies' decline are still not clear 
(University of California Berkeley 2009, p. 1), it is thought that 
overgrazing by livestock, combined with drought, so greatly reduced the 
larval food plant that the butterfly could no longer survive (Orsak 
1974, in Hammond and McCorkle 1983, p. 220). Wildfire suppression 
practices may also have contributed to the spread of nonnative 
vegetation in the area, which tends to outcompete native low-growing 
annuals, including potential unsilvered fritillary host plants (John 
Emmel, pers. comm. in Bruyea 2003, not paginated).
    The petition states that population and urban growth and 
development are important stressors to wildlife in the central coast 
region of California, including the unsilvered fritillary, and that 
suburban development has reduced both the various Speyeria species of 
butterflies and violets, their primary food source (WildEarth Guardians 
2010, p. 8). As stated in the petition, the human population in this 
region has increased extensively and is likely continuing to grow 
(WildEarth Guardians 2010, p. 8). According to the California Wildlife 
Action Plan (Bunn et al. 2007, p. 200), population pressures have 
increased in recent years, and growth and development have expanded 
from urban centers to adjacent farmlands and rural areas both on the 
coast and in the interior portions of the central coast. As pointed out 
in the petition, these developed areas and infrastructure corridors not 
only result in direct loss of habitat, but also fragment the natural 
landscape and degrade the quality of adjacent habitat (WildEarth 
Guardians 2010, p. 9). Fragmentation hinders ecological processes that 
require landscape connectivity, such as natural fire regimes, movement 
of wide-ranging species, and genetic exchange, and it makes remaining 
natural lands more vulnerable to pollution and invasion by exotic 
plants and animals (Soul[eacute] and Terborgh 1999, in Bunn et al. 
2007, p. 208).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    As noted in the petition, Speyeria are known to be sensitive to 
development, and development is considered to be a threat to the 
habitat of the four listed Speyeria butterflies. The primary threat to 
the Callippe (62 FR 64306), Behren's (62 FR 64306), Myrtle's (June 22, 
1992, 57 FR 27848), and Oregon silverspot (July 2, 1980, 45 FR 44935) 
butterflies is the loss and degradation of habitat from human 
activities.

[[Page 10314]]

    The petition asserts that urban and rural development is occurring 
within the range of the unsilvered fritillary and is negatively 
affecting it (WildEarth Guardians 2010, p. 8). We agree that the 
unsilvered fritillary is likely sensitive to development that removes 
or degrades its habitat; however, the petition only makes general 
assertions that development associated with population increases in the 
central coast is affecting the habitat of the unsilvered fritillary. 
The petition does not provide any information on the location of 
populations of the unsilvered fritillary or either of the two extant 
subspecies, except for the one occurrence of a protected population in 
Big Basin Redwoods State Park (WildEarth Guardians 2010, p. 11). The 
petition also does not provide any information regarding the amount of 
occupied habitat lost or degraded, nor does the petition identify areas 
within the unsilvered fritillary's range that are currently being 
developed or have plans for future development. As noted above in the 
Species Information section, only two records of the unsilvered 
fritillary are in the CNDDB, one of which is in Big Basin Redwoods 
State Park, where development, agriculture, and off-road vehicles are 
not permitted. The petition references NatureServe in indicating that 
``few to several'' occupied locations are protected, but it does not 
include any further information, nor does the petition include any land 
ownership information, beyond the fact that one of the locations is in 
Big Basin Redwoods State Park (WildEarth Guardians 2010, p. 11). We 
have no information in our files regarding specific locations of 
unsilvered fritillary butterfly populations, suitable habitat, or 
potential development impacts to the habitat for the species or 
subspecies. However, based on maps in our files, there are six State 
parks (Butano, Portola, Castle Rock, Henry Cowell Redwoods, Forest of 
Nisene Marks, and Wilder Ranch State Park), the extensive San Francisco 
State Fish and Game Refuge, and several County parks (e.g., San Pedro, 
Mt. Madonna, Uvas Canyon County Park) in the range of the species 
(Santa Cruz Mountains) that are not mentioned in the petition. Also, 
almost half of the range of the clemencei subspecies as identified in 
the petition (WildEarth Guardians 2010, p. 5) is public land, including 
the Los Padres National Forest, Ventana Wilderness Area, Hastings 
Natural History Reservation, and several State parks (e.g., Pfeiffer 
Big Sur, Julia Pfeiffer Burns). Although we do not have any information 
as to the presence of populations or suitable habitat in these areas, 
they are all within the range of the fritillary and are protected from 
many types of impacts including development, agriculture, and, at least 
in the case of the Ventana Wilderness Area and State parks, off-road 
vehicles (Wilderness Act of 1964 (16 U.S.C. 1131 et seq.); https://www.parks.ca.gov/). Therefore, we have determined that the information 
provided in the petition and in our files concerning the effect of 
development on the unsilvered fritillary or either of its two 
subspecies does not present substantial information indicating that the 
petitioned action may be warranted.
Fire: Information in the Petition
    The petition asserts that the unsilvered fritillary is a poor 
survivor of fires, but that the species also depends on fire to protect 
its habitat from brush and tree encroachment as well as to burn off 
dead thatch that can crowd out violets (WildEarth Guardians 2010, p. 8, 
citing Hammond and McCorkle 1983, p. 222; NatureServe 2009, not 
paginated). Wildfire suppression may also facilitate the spread of 
exotic vegetation (WildEarth Guardians 2010, p. 9, citing Bruyea 2003, 
not paginated). The petition states that the Service should consider 
how an altered fire regime may be a threat to this species' habitat, 
particularly given that the clemencei subspecies occurs in the fire-
prone Santa Lucia range (WildEarth Guardians 2010, p. 8, citing 
NatureServe 2009, not paginated).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    Periodic fires can be an important factor in maintaining the 
grassland and coastal prairie habitat of the Callippe and Behren's 
silverspot butterflies, because, without fire, succession will 
eliminate the food plants of the larvae of the two butterflies (Orsak 
1980 and Hammond and McCorkle 1984 in 62 FR 64306, p. 64315). Hammond 
and McCorkle (1983, p. 222) pointed out that without fire to maintain 
the grasslands against brush and tree invasion along the Oregon and 
Washington coasts, most of the coastal grasslands gradually disappeared 
to salal and salmonberry brushland or Sitka spruce forest, and even 
without brush and tree invasion, the native grasslands experience a 
second ecological problem in the absence of fire. The dead grass from 
the previous year's growth does not decay quickly in the coastal 
environment and gradually accumulates to form a thick layer of thatch 
that smothers and crowds out the violets and other wildflowers that are 
important food sources for butterflies (Hammond and McCorkle 1983, p. 
222). The reduction of historic disturbance regimes has probably 
accelerated expansion of several nonnative species which threaten 
Oregon silverspot populations, in addition to encouraging native shrub 
and tree growth. The spread of nonnative plants has reduced, degraded, 
or eliminated habitat for the Oregon silverspot at many sites (Service 
2001, p. 16). The overgrowth of invasive plants remains one of the most 
serious present-day threats to the Myrtle's silverspot butterfly. It 
has been recognized as a threat to other listed butterflies as well (57 
FR 27848; Service 1998; Adams 2004; Ehrlich and Hanski 2004; Severns 
2007, in Service 2009, p. 15).
    While the overgrowth and succession of the four Speyeria butterfly 
habitats may be ameliorated by periodic disturbance from fires that 
clear areas for Speyeria food plants, the effects on Speyeria larvae 
may be more severe. Although the larvae of these butterflies may 
survive fires that move rapidly through grassland habitats, hotter and 
slow-moving brush and woodland fires may kill them (Orsak 1980 and 
Hammond and McCorkle 1984 in 62 FR 64306, p. 64315). Under windy 
conditions, fast-moving grassland fires burn in patches that leave 
islands of unburned habitat where any butterflies present are not 
harmed.
    The petition asserts that the unsilvered fritillary can be 
negatively or positively affected by both presence of fire and absence 
of fire (WildEarth Guardians 2010, p. 8). However, the petition does 
not provide any information on past or more-recent fire activity within 
the range of the unsilvered fritillary and does not provide any 
information on the location of populations of the unsilvered 
fritillary, including either of its two subspecies that may or could 
potentially be affected by fire. Similarly, the petition does not 
provide any information on past, present, or planned fire suppression 
activities within the range of the species. Moreover, the petition 
(WildEarth Guardians 2010, p. 8) and NatureServe (2009) state that the 
Santa Lucia Mountains are fire prone, but do not provide information 
regarding the past or more-recent fire history in the Santa Lucia 
Mountains that would indicate this area is more fire-prone or whether 
the clemencei subspecies' habitat is more prone to wildfire than other 
areas of California. We have no information for either the specific 
locations of the unsilvered fritillary populations that may be

[[Page 10315]]

affected by fire, or the areas within the range of the species that 
have altered fire regimes or have high fire danger. Therefore, we have 
determined that the information provided concerning wildfire and fire 
suppression for the unsilvered fritillary or either of its extant 
subspecies does not present substantial information indicating that the 
petitioned action may be warranted.
Agriculture and Grazing: Information Provided in the Petition
    The petition lists agriculture and livestock grazing as threats to 
the unsilvered fritillary and asserts that livestock eat and trample 
violet food plants and can cause proliferation of noxious weeds that 
displace violets (WildEarth Guardians 2010, p. 9). The petition asserts 
that approximately 11 percent of the central coast region of California 
is used for agriculture and livestock grazing, which can lead to 
habitat fragmentation, erosion, sedimentation, and degradation from 
herbicides and insecticides (WildEarth Guardians 2010, p. 9). The 
petition states that intensive agriculture is increasing in the region; 
vineyard acreage increased approximately 36 percent between 1998 and 
2001 (WildEarth Guardians 2010, p. 9, citing Bunn et al. 2007, p. 211). 
The petition (WildEarth Guardians 2010, p. 8) notes that overgrazing is 
suspected to have played a role in the extinction of the atossa 
subspecies (NatureServe 2009, not paginated).
    The petition also states that Speyeria butterflies are known to be 
susceptible to insecticides (WildEarth Guardians 2010, p. 16, citing 
NatureServe 2009, not paginated), and given the increase in agriculture 
within the unsilvered fritillary's range, insecticide use is likely to 
be an escalating threat to this species (WildEarth Guardians 2010, p. 
16).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The effect of grazing can be either beneficial or deleterious to 
native plants, depending on the grazing regime and the ecology of the 
plant species (DeVries and Raemakers 2001; Vogel et al. 2007, in 
Service 2009, p. 14). For the Callippe, Behren's, Myrtle's, and Oregon 
silverspots, livestock grazing was determined to be a threat if it 
occurred at levels such that the vegetation was overgrazed and the food 
plants and nectar sources of these butterflies were eliminated or 
reduced in abundance. However, light-to-moderate grazing can result in 
reduction of invasive woody plants and maintain early successional 
grassland habitats that are beneficial for butterfly host plants 
(Service 2001, p. 16; Service 2009, p. 14). In fact, the Myrtle's 
silverspot has coexisted with cattle grazing for over 100 years at 
Point Reyes National Seashore. Adams (2004, in Service 2009, p. 14) 
found that the moderate grazing regime at Point Reyes National Seashore 
did not negatively affect the density or diversity of nectar plants, 
and butterflies were found more frequently in the areas that were 
grazed. Inadvertent trampling of the Myrtle's silverspot host plants by 
grazing cattle may also be considered a relatively minor threat 
(Service 2009, p. 14). Other studies have shown that optimal grazing 
increases the density of native plants, which may support butterfly 
populations (Heitschmidt and Stuth 1991 in Service 2009, p. 14).
    The petition asserts that because 11 percent of the central coast 
region is used for agriculture and grazing, and because intensive 
agriculture (e.g., vineyards) is increasing in the region, the 
unsilvered fritillary is and will become even more negatively affected 
by these land uses (WildEarth Guardians 2010, p. 9). While conversion 
of suitable habitat containing Viola spp. host plants to intensive 
agriculture would most likely eliminate the unsilvered fritillary's 
habitat, the petition does not provide any information, nor do we have 
any information in our files, regarding the extent or intensity of 
existing agriculture and grazing land use or any planned land-use 
conversion to vineyards or other types of agriculture or grazing that 
would occur within the unsilvered fritillary's range. Also, although 
vineyard acreage has increased along the central coast, as pointed out 
in the petition (WildEarth Guardians 2010, p. 9), much of the increase 
has been south of the area where the unsilvered fritillary is currently 
believed to occur, in the Santa Cruz Mountains and the Santa Lucia 
Mountains. Vineyard acreage has increased in the area around Paso 
Robles in San Luis Obispo County and Santa Barbara County (Bunn et al. 
2007, p. 211). The petition does not provide any information, nor do we 
have any information in our files, on the location of populations of 
the unsilvered fritillary that may be or could potentially be affected 
by agriculture or grazing, and, thus, we do not have information 
indicating that agriculture and grazing practices are negatively 
affecting, or are likely to negatively affect, the unsilvered 
fritillary. We have determined that the information presented in the 
petition and available in our files concerning potential habitat 
modification threats of agriculture and grazing to the habitat for the 
unsilvered fritillary or either of its extant subspecies does not 
present substantial information indicating that the petitioned action 
may be warranted.
    Silverspot butterfly larvae are extremely sensitive to 
insecticides, and even the accumulation of runoff in the soil after 
spraying has proven lethal to the larvae of members of the genus 
Speyeria (Mattoon et al. 1971, in 62 FR 64306, p. 64314). In listing 
the Callippe and Behren's silverspot butterflies, the Service stated 
that the use of insecticides could threaten these butterflies if use 
occurred in proximity to occupied habitat (62 FR 64306, p. 64314). This 
petition, however, does not provide information regarding the use of 
insecticides within the unsilvered fritillary's range and simply 
asserts that insecticide use would increase as agriculture within the 
region increases. The petition also does not provide any information on 
the location of populations of the unsilvered fritillary that may or 
could potentially be affected by insecticides. The Service is not aware 
of plans to apply insecticides in or near the habitat occupied by the 
unsilvered fritillary, nor do we have any information in our files 
regarding areas of insecticide application relative to unsilvered 
fritillary habitat. Therefore, we have determined that the information 
presented in the petition and in our files concerning the potential 
threat of insecticides to the unsilvered fritillary or either of its 
extant subspecies does not present substantial information indicating 
that the petitioned action may be warranted.
Exotic (Nonnative) Vegetation: Information in the Petition
    The petition states that exotic vegetation may have played a role 
in the extinction of the atossa subspecies and asserts that exotic 
vegetation could likewise threaten the extant subspecies of the 
unsilvered fritillary and the species as a whole (WildEarth Guardians 
2010, p. 9). Citing Bruyea (2003, not paginated), the petition points 
to wildfire suppression as having facilitated the spread of exotic 
vegetation, which outcompeted native annuals, such as violets, and, in 
combination with other human disturbances, led to the extinction of the 
atossa subspecies (WildEarth Guardians 2010, p. 9).
    The petition points out that in the listing rule for the Behren's 
and Callippe silverspot butterflies (62 FR 64306, pp. 64314-64315), the 
Service noted, ``The invasion of California's native grassland and 
coastal prairie by

[[Page 10316]]

alien plants has adversely affected native flora and fauna. In the 
absence of control and eradication programs, invasive alien plants may 
eliminate the remaining native plants, including the host plants of 
Behren's and Callippe silverspot butterflies. Adequate levels of Viola 
spp. host plants are especially critical for the long-term survival of 
populations of these butterflies (S. Mattoon, in litt., August 4, 1989, 
and November 22, 1992).'' The petition states that this analysis 
likewise applies to the unsilvered fritillary (WildEarth Guardians 
2010, p. 9).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We recognize that nonnative vegetation can reduce and degrade 
habitat for Speyeria butterflies (e.g., Service 2001, p. 16; Service 
2009, p. 15), and that nonnative vegetation has been recognized as an 
indirect threat to other listed butterflies as well (57 FR 27848; 
Service 1998; Adams 2004; Ehrlich and Hanski 2004; Severns 2007 in 
Service 2009, p. 15). In the absence of control and eradication 
programs, invasive alien plants may eliminate the remaining native 
plants, including the host plants of Behren's and Callippe silverspot 
butterflies. The petition generalized that because other Speyeria 
butterflies are negatively impacted by nonnative vegetation, the 
unsilvered fritillary is as well (WildEarth Guardians 2010, p. 9). 
However, the petition does not include any information on where 
nonnative vegetation is degrading the unsilvered fritillary's habitat 
or the location of populations of the unsilvered fritillary that may be 
or could potentially be affected by nonnative plants. In addition, we 
have no information in our files regarding negative impacts to the 
unsilvered fritillary due to nonnative vegetation. Therefore, we have 
determined that the information presented in the petition and in our 
files concerning the potential threat of nonnative plants to the 
habitat of the unsilvered fritillary or either of its extant subspecies 
does not present substantial information indicating that the petitioned 
action may be warranted.
Drought: Information Provided in the Petition
    The petition states that drought is considered a threat to the 
unsilvered fritillary (WildEarth Guardians 2010, p. 14, citing 
NatureServe 2009, not paginated). Drought has been hypothesized, but 
not definitively proven, to be a factor in the extinction of the atossa 
subspecies, as well as being a threat to the clemencei subspecies 
(WildEarth Guardians 2010, p. 14, citing Davenport 2004, p. 16; 
NatureServe 2009, not paginated). The petition also asserts that 
climate change will result in more frequent and longer droughts 
(WildEarth Guardians 2010, p. 14).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The petition does not provide any information, nor do we have 
information in our files, to indicate that drought has or will 
negatively affect the habitat or the number and distribution of 
populations or the population sizes of the unsilvered fritillary. The 
petition cites sources that state generally that drought has been a 
severe problem in recent years (WildEarth Guardians 2010, p. 14, citing 
Davenport 2004, p. 16), but does not provide information specifically 
related to the effects of drought on the unsilvered fritillary. The 
cause of the extinction of the atossa subspecies is unclear, but it has 
been attributed to many different factors, including drought (Howe 
1975, in Bruyea 2003, not paginated; Orzak 1974, in Hammond and 
McCorkle 1983, p. 220), overgrazing (Orzak 1974, in Hammond and 
McCorkle 1983, p. 220), disease (University of California Berkeley 
2009, p. 1), invasion of nonnative species (Howe 1975, in Bruyea 2003, 
not paginated), and wildfire suppression (John Emmel, pers. comm., in 
Bruyea 2003, not paginated). Periodic droughts have been, and likely 
will continue to be, a normal part of the climate of California, and 
wildlife, including the unsilvered fritillary, have adapted to periodic 
droughts. Therefore, we have determined that the information presented 
in the petition and in our files concerning the potential threat of 
drought to the unsilvered fritillary or either of its extant subspecies 
does not present substantial information indicating that the petitioned 
action may be warranted.
Climate Change: Information Provided in the Petition
    The petition asserts that climate change is having, and will 
continue to have, a multitude of effects on the unsilvered fritillary 
and its habitat, including more severe, longer, and more frequent 
droughts; increased catastrophic wildfire and alteration of natural 
fire regimes due to hotter conditions; and potential shifts in ranges 
of this species or the violet species on which it depends (WildEarth 
Guardians 2010, p. 12). The petition notes that recent warming in the 
southwestern United States is among the most rapid in the nation, 
significantly more rapid than the global average (WildEarth Guardians 
2010, p. 12, citing Karl et al. 2009, pp. 129-132). Increasing 
temperature, drought, wildfire, and invasive species will accelerate 
transformation of the landscape; two-thirds of the more than 5,500 
native plant species in California are projected to experience range 
reductions of up to 80 percent before the end of this century under 
projected warming (WildEarth Guardians 2010, p. 13, citing Karl et al. 
2009, p. 132). The petition claims that such a shift in native 
ecosystems could adversely affect the unsilvered fritillary, given its 
narrow distribution (WildEarth Guardians 2010, p. 13).
    The petition cites a recent United States Forest Service report 
regarding the intersection of climate and fire regimes (WildEarth 
Guardians 2010, p. 14, citing Westerling et al. 2006, in Keeley et al. 
2009, p. 20). The report states that recent studies show correlations 
among warming temperatures, earlier springs, and increased numbers of 
large forest fires in some parts of the western United States. 
Anticipated warming trends as a consequence of greenhouse gas 
accumulation may lead to further increases in the numbers of large 
fires and total area burned in some regions (Brown et al. 2004; 
Flannigan et al. 2005; McKenzie et al. 2004, in Keeley et al. 2009, p. 
20). Allen and Breshears (1998, in Keeley et al. 2009, p. 20) also 
predict that global climate change will produce large changes in 
vegetation distributions at unprecedented rates, particularly in 
semiarid, fire-prone ecosystems. These anticipated changes in fuel 
distribution could reduce fire activity in some regions and lead to 
unanticipated impacts on future fire regimes (Keeley et al. 2009, p. 
20).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We recognize that global mean temperatures have increased over the 
last several decades and will almost certainly continue to increase in 
the future as a result of greenhouse gases. Although increasing 
temperature may have an effect on the unsilvered fritillary, the 
information presented in the petition or available in our files does 
not support a meaningful prediction as to whether the overall impact 
will be negative or positive, or some combination of negative and 
positive impacts. Increasing temperature could result in more severe 
and frequent drought, especially in the Southwest (Karl et al. 2009, p. 
42). However, we are

[[Page 10317]]

not aware of any formal studies on the direct effect of rising global 
temperature on drought severity or frequency (Karl et al. 2009, p. 5). 
Also, drought severity and frequency are a function of a complex series 
of factors, such as El Ni[ntilde]o intensity and duration and 
geographic variations in sea surface temperature, which may also be 
affected in some manner by increasing temperatures, thereby compounding 
the uncertainty associated with precipitation projections (Karl et al. 
2009, p. 105). Uncertainty also arises when extrapolating from a larger 
scale (e.g., North America or the Southwest) to the limited range of 
the unsilvered fritillary. A projected increase in mean temperatures in 
the Southwest does not necessarily equate to a similar degree of 
increase in local areas, such as the central coast of California, and 
both the degree and direction of changes in climate and weather will 
vary at the local level. More importantly, the response of plants and 
animals to climate change is uncertain and will likely vary locally and 
regionally. For example, citing Karl et al. (2009, p. 132), the 
petition states that the ranges of many California plants are projected 
to decline up to 80 percent due to climate change. However, this 
projection is only one of many projections. The 80-percent projection 
is a worst-case scenario in which the most severe degree of climate 
change was assumed, and in which plants were assumed to have no ability 
to shift their range in response to climate change. Other scenarios, 
where plants were assumed to be able to shift range, revealed that 
plant ranges in some areas were projected to increase, such as in the 
Central Western region which includes the range of the unsilvered 
fritillary (Loarie et al. 2008, Figure 4, p. 6). In addition, although 
the range of some types of vegetation may decline, grasslands are 
expected to increase (Karl p. 131), which may be beneficial for the 
unsilvered fritillary. Finally, we cannot meaningfully predict the 
impact on the unsilvered fritillary if drought severity and frequency 
were to increase in the central coast. For example, wildfires are 
likely to increase with worsening droughts (Karl et al. 2009, p. 43), 
but as pointed out in the petition, wildfires may have a positive as 
well as a negative effect on the unsilvered fritillary and its habitat. 
Therefore, we have determined that the information presented in the 
petition and in our files concerning the potential threat of climate 
change to the unsilvered fritillary or either of its extant subspecies 
does not present substantial information indicating that the petitioned 
action may be warranted.
Summary of Factor A
    The petition lists development, agriculture, livestock grazing, 
insecticides, invasive plants, drought, and climate change as threats 
to the unsilvered fritillary. However, the petition provided only this 
general list of potential threats to the unsilvered fritillary, but did 
not provide information that these potential threats are acting on the 
habitat of the unsilvered fritillary. We recognize that other listed 
Speyeria butterflies have been reduced, some substantially, due to 
human-caused disturbances, but the petition does not cite any site-
specific proposed development projects or land-use conversion projects 
that would occur within unsilvered fritillary habitat. In addition, the 
petition does not provide specific information on the location(s) of 
unsilvered fritillary populations. Therefore, it is not possible to 
determine if a development project would actually affect the unsilvered 
fritillary, given that we do not have recent data detailing where this 
species occurs. The best information that we have regarding the 
location of known populations is the two records in the CNDDB, one of 
which is in a State park and is protected by California State law 
(NatureServe 2009, not paginated). Also, a large portion of the 
clemencei subspecies' range is public land and therefore protected from 
many sources of habitat destruction and alteration. The petition also 
does not provide any information that any other threats to the 
unsilvered fritillary's habitat--including agriculture, livestock 
grazing, insecticides, or invasive plants--are occurring within the 
current range of the species and its two remaining subspecies, or are 
threatening the habitat of the species. There is ample evidence that 
global mean temperatures will likely increase in the future due to 
greenhouse gases; however, the petition does not present any 
information, nor do we have any information in our files, that 
indicates that the local climate and weather of the central coast is 
likely to change, the projected degree and nature of any change, or 
that drought is likely to increase in severity or frequency. 
Consequently, we find that the information provided in the petition and 
in our files does not present substantial scientific or commercial 
information indicating that listing the unsilvered fritillary or either 
of its extant subspecies may be warranted due to the present or 
threatened destruction, modification, or curtailment of the species' 
habitat or range.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

Information Provided in the Petition
    The petition states that collection is not known to constitute a 
threat to the unsilvered fritillary; however, the rarity of the species 
makes it more attractive to collectors (WildEarth Guardians 2010, p. 
9). The petition also states that butterfly populations that are small 
and easily accessible are especially vulnerable to overcollection 
(WildEarth Guardians 2010, p. 9).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The petition does not provide any information, nor do we have any 
information in our files, that would indicate that the unsilvered 
fritillary is a target of collectors or that it is threatened by 
collection. Although an extensive commercial trade has been documented 
for the Callippe silverspot and the Behren's silverspot butterflies, as 
well as for other imperiled and rare butterflies (U.S. Attorney's 
Office 1994, United States v. Richard J. Skalski, Thomas W. Kral, and 
Marc L. Grinnell, Case No. CR932013, 1993, in 62 FR 64306, p. 64313), 
insects are rarely affected by human overcollecting pressures, due to 
their high reproductive capabilities (Pyle, Bentzien, and Opler 1981, 
in Hammond and McCorkle 1983, p. 218).
    In summary, we find that the information provided in the petition 
and available in our files does not present substantial scientific or 
commercial information indicating that listing the unsilvered 
fritillary or either of its extant subspecies may be warranted due to 
overutilization for commercial, recreational, scientific, or 
educational purposes.

C. Disease or Predation

Information Provided in the Petition
    The petition states that adult and larval butterflies are subject 
to predation by a wide variety of vertebrate and invertebrate wildlife 
(e.g., birds, reptiles, amphibians, and other insects) and that the 
small size of unsilvered fritillary populations increases their 
vulnerability to extirpation from disease or predation (WildEarth 
Guardians 2010, p. 10). The petition also states that scientists have 
suggested that disease could explain the extinction of the atossa 
subspecies; however, drought and overgrazing have also been mentioned 
as reasons for this subspecies' extinction (WildEarth

[[Page 10318]]

Guardians 2010, p. 9, citing Orzak 1974, in Hammond and McCorkle 1983, 
p. 220).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The petition does not provide any information that would indicate 
that disease or predation are threats to the unsilvered fritillary, nor 
do we have any information in our files that would indicate that 
disease or predation are threats to the species. Disease has been 
suggested as a potential cause of the extinction of the atossa 
subspecies (University of California Berkeley 2009, p. 1). However, the 
petition did not present any information that would substantiate that 
claim, and the extinction of the atossa subspecies has also been 
attributed to several other causes. The petition also did not provide 
any information on the types of diseases known to occur in the 
unsilvered fritillary or other Speyeria butterflies or any species of 
butterfly or their vulnerability to disease. Therefore, we find that 
the information provided in the petition and available in our files 
does not present substantial scientific or commercial information 
indicating that listing the unsilvered fritillary or either of its 
extant subspecies may be warranted due to disease or predation.

D. The Inadequacy of Existing Regulatory Mechanisms

Information Provided in the Petition
    The petition asserts that the unsilvered fritillary is not 
adequately protected by Federal or State laws or policies to prevent 
its endangerment or extinction (WildEarth Guardians 2010, p. 10). The 
unsilvered fritillary is not listed under the Act, nor are any of its 
subspecies. The species is also not listed under the California 
Endangered Species Act (CESA), because the CESA does not provide for 
the listing and protection of insects. The petition further states that 
while the various rankings of the unsilvered fritillary and its 
subspecies by NatureServe (e.g., G1G2), CNDDB, and the California 
Wildlife Action Plan (see Species Information section) indicate 
biological imperilment, they do not provide any regulatory or policy 
mechanisms to protect the unsilvered fritillary (WildEarth Guardians 
2010, p. 10). The petition provides no further information on any other 
State, Federal, or local regulations.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    As discussed in the petition and in the Species Information section 
above, several sources express concern over the status of the 
unsilvered fritillary, and the species is included in the State's CNDDB 
list of at-risk species (WildEarth Guardians 2010, p. 11). However, 
contrary to the petition, we believe that the at-risk classification 
extends some level of consideration under the California Environmental 
Quality Act when project impacts are reviewed. Also, one of the two 
occurrences in the CNDDB is within Big Basin Redwoods State Park, and 
its habitat within the park is afforded a high degree of protection by 
State law and regulations. Additionally, information in our files 
indicates that a substantial portion of the putative range of the 
unsilvered fritillary, as identified in the petition (WildEarth 
Guardians 2010, p. 5), is public land (Ventana Wilderness, Los Padres 
National Forest, and State and County parks), where, if present, the 
species would be protected from many types of impacts (e.g., 
development, agriculture, and, at least in the case of Ventana 
Wilderness and State parks, off-road vehicles) by Federal, State, and 
local laws and regulations. Therefore, we find that the information 
provided in the petition and available in our files does not present 
substantial scientific or commercial information indicating that 
listing the unsilvered fritillary or either of its extant subspecies 
may be warranted due to the inadequacy of existing regulatory 
mechanisms. There are no significant threats to the species as 
discussed in factors A, B, C, and E.

E. Other Natural or Manmade Factors Affecting the Species' Continued 
Existence

Biological Vulnerability: Information Provided in the Petition
    The petition states that because the unsilvered fritillary's range 
was historically limited, has been further reduced by anthropogenic 
causes, and is vulnerable to weather events such as drought and 
catastrophic fires, the Service should consider this butterfly's narrow 
range itself as a threat to the taxon (WildEarth Guardians 2010, pp. 
15-16). For example, loss of habitat and populations of another 
Speyeria species, the Regal fritillary (Speyeria idalia), have 
disrupted the gene flow between populations, and the species is 
consequently more prone to extinction due to genetic and demographic 
factors (WildEarth Guardians 2010, p. 16, citing Williams et al. 2003, 
p. 17). The petition further states that the Service has routinely 
recognized that small population size and restricted range increase the 
likelihood of extinction (WildEarth Guardians 2010, p. 15). The 
petition also lists human population growth (see factor A for a 
discussion of population growth and development), insecticide use (see 
factor A for a discussion of insecticide use), and nonnative thistle 
seed weevils (scientific name not provided in petition) as threats to 
the unsilvered fritillary. Finally, the petition asserts that the 
cumulative effects of grazing, development, agriculture, off-road 
vehicles, and climate change threaten the species.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We recognize the risks that stochastic (random chance) events may 
present to small populations, and we agree that the limited range of 
the unsilvered fritillary may exacerbate its vulnerability to these 
events. However, the mere fact that a rare species is potentially 
vulnerable to stochastic processes does not necessarily mean that it is 
reasonably likely to experience, or have its status affected by, a 
given stochastic process. There must be some information to indicate 
that the unsilvered fritillary and its habitat are at least susceptible 
to a threat or stochastic event, such as a severe, widespread disease 
among its host plants, and that the species would be negatively 
affected by the event. Typically, it is the combination of small size, 
the number of populations, and isolation of small populations, in 
conjunction with a threat or stochastic event (e.g., catastrophic 
fire), that may pose a threat to a species. The petition, however, 
includes only very limited information on the number of populations and 
does not provide information on the distribution and size of 
populations or the presence or absence of connectivity between 
populations. Also, the mere fact that a species is rare does not 
necessarily equate to a threat. A species that has always been rare, 
yet continues to survive, could be well equipped to continue to exist 
into the future. Many naturally rare species have persisted for long 
periods within small geographic areas, and many naturally rare species 
exhibit traits that allow them to persist despite their small 
population sizes.
    The petition states that ``nonnative thistle seed weevils may also 
pose a threat to the unsilvered fritillary'' (WildEarth Guardians 2010, 
p. 16, NatureServe 2009, not paginated). However, neither the petition 
nor

[[Page 10319]]

NatureServe provides any other information on thistle seed weevils or 
the impact they may have on the unsilvered fritillary. We assume that 
weevils can destroy thistles, which are one of the plants on which the 
unsilvered fritillary has been observed feeding (NatureServe 2009, not 
paginated). However, beyond that, we have no information in our files, 
and the petition did not provide any information that thistle seed 
weevils occur within the range of the unsilvered fritillary, or that 
they are destroying substantial numbers of thistles.
    The information in the petition and in our files on the potential 
impacts of grazing, development, agriculture, off-road vehicles, and 
climate change are discussed in factor A. These potential impacts in 
combination could have a greater effect on the unsilvered fritillary 
than they would have individually. However, as summarized in factor A, 
the petition provided only this general list of potential threats to 
the unsilvered fritillary, but did not provide information that these 
potential threats are acting on the habitat of the unsilvered 
fritillary. The petition also did not provide any information that 
multiple potential threats are acting together on the habitat of the 
unsilvered fritillary.
    In summary, we find that the information provided in the petition 
and available in our files does not present substantial scientific or 
commercial information indicating that listing the unsilvered 
fritillary or either of its extant subspecies may be warranted due to 
other natural or manmade factors affecting the species' continued 
existence.

Finding

    In summary, the petition does not present substantial scientific or 
commercial information, because it does not provide any information on 
the location and magnitude of threats within the range of the species 
or specific threats to any occurrence or population of the species or 
either of its extant subspecies. The petition provides only very 
limited information on the number of populations within this area and 
no information on the distribution and size of populations, and we do 
not have this info