[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 http://www.regulations.gov at Docket Number FWS-R8-ES-2010-0078 and at http://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.); http://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 information in our files. The unsilvered fritillary is a
rare butterfly occurring in the Santa Cruz Mountains of San Mateo,
Santa Cruz, and Santa Clara Counties, and in the Santa Lucia Mountains
of Monterey and San Luis Obispo Counties, California, which is an area
encompassing thousands of square miles. The petition cites threats to
other listed Speyeria butterflies and requests we consider those
relative to the unsilvered fritillary. While four other Speyeria
species are listed as either threatened or endangered, the fact that
these species are listed under the Act does not in and of itself mean
that the unsilvered fritillary or either of its extant subspecies is
threatened or endangered.
In considering what factors might constitute threats, we must look
beyond the mere exposure of the species to the factor to determine
whether the species responds to the factor in a way that causes actual
impacts to the species. If there is exposure to a factor, but no
response, or only a positive response, that factor is not a threat. If
there is exposure and the species responds negatively, the factor may
be a threat and we then attempt to determine how significant a threat
it is. If the threat is significant, it may drive or contribute to the
risk of extinction of the species such that the species may warrant
listing as threatened or endangered as those terms are defined by the
Act. This does not necessarily require empirical proof of a threat. The
combination of exposure and some corroborating evidence of how the
species is likely impacted could suffice. The mere identification of
factors that could impact a species negatively may not be sufficient to
compel a finding that listing may be warranted. The information must
contain evidence sufficient to suggest that these factors may be
operative threats that act on the species to the point that the species
may meet the definition of threatened or endangered under the Act. We
found no information to suggest that threats are acting on the
unsilvered fritillary such that the species may become extinct now or
in the foreseeable future.
On the basis of our determination under section 4(b)(3)(A) of the
Act, we conclude that the petition does not present substantial
scientific or commercial information to indicate that listing the
unsilvered fritillary or either of its extant subspecies under the Act
as threatened or endangered may be warranted at this time. Although we
will not review the status of the species at this time, we encourage
interested parties to continue to gather data that will assist with the
conservation of the unsilvered fritillary or either of its extant
subspecies. If you wish to provide information regarding the unsilvered
fritillary or either of its extant subspecies, you may submit your
information or materials to the Field Supervisor, Ventura Fish and
Wildlife Office (see ADDRESSES), at any time.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Ventura Fish and
Wildlife Office (see ADDRESSES).
Author
The primary authors of this notice are the staff members of the
Ventura 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: February 7, 2011.
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2011-4037 Filed 2-23-11; 8:45 am]
BILLING CODE 4310-55-P