10310 Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 

they are managed as a conservation 

herd, rather than as a commercial herd. 

However, we no longer consider the 

Yellowstone herd to have remained in 

more of a ‘‘wild’’ state than any other 

conservation herd. Specifically, these 

wild plains bison are no longer thought 

to have remained in an unaltered 

condition from prehistoric times, as 

implied in the previous determination. 

In 1902, no more than 30 wild plains 

bison remained in Yellowstone (Halbert 

2003, p. 24). In the same year, 18 female 

plains bison from the captive PabloAllard herd in Montana and 3 bulls 

from the captive Goodnight herd in 

Texas were purchased to supplement 

the Yellowstone herd (Halbert 2003, pp. 

24–25). Additionally, intensive 

management (supplemental feeding, 

roundups, and selective culling) of the 

Yellowstone herd occurred from the 

1920s through the late 1960s (Gogan et 

al. 2005, p. 1719). Wild plains bison 

from Yellowstone also have been used 

to start or augment many later 

conservation herds (Halbert and Derr 

2007, p. 2). Despite geographic 

separation, the Yellowstone herd is 

essentially part of one metapopulation 

and is not markedly separate from other 

herds. 

Summary of the Distinct Population 

Segment Analysis 

On the basis of the preceding 

discussion, we believe that the petition 

has not provided substantial 

information to conclude that each of the 

four population segments may be 

discrete. Therefore, we did not evaluate 

significance or conservation status of 

the four population segments within the 

meaning of the DPS Policy. In 

conclusion, we do not believe that any 

of the population segments may 

constitute a valid DPS. 

However, even if we had concluded 

that the four population segments may 

be discrete and significant, the petition 

does not present substantial information 

that any of the stressors described under 

the above five factor analysis are 

concentrated within any one DPS to 

indicate that any of the DPSs would be 

more likely to be threatened or 

endangered than the species at large. 

Thus, there is no information indicating 

stressors rise to the level of a threat for 

any population segment. 

Finding 

In summary, the petition does not 

present substantial information that 

wild plains bison may require listing 

either as a subspecies or a DPS. The 

conclusion that impacts from the 

various factors discussed above may 

constitute a threat is not supported by 

the available information regarding 

distribution, abundance, and population 

trends of wild plains bison. Wild plains 

bison are distributed in parks, preserves, 

other public lands, and private lands 

throughout and external to their 

historical range. The current population 

of wild plains bison is estimated to be 

20,500 animals in 62 conservation 

herds. Recent population trends appear 

stable to slightly increasing in 

conservation herds (as noted by the 

petitioners). 

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 wild plains bison, or any of 

four proposed DPSs, 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 conservation of the wild 

plains bison. If you wish to provide 

information regarding the wild plains 

bison, you may submit your information 

or materials to the Wyoming Field 

Supervisor (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 Wyoming Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Authors 

The primary authors of this notice are 

staff members of the Mountain-Prairie 

Regional Office and the Wyoming Field 

Office (see ADDRESSES). 

Authority 

The authority for this action is the 

Endangered Species Act of 1973, as 

amended (16 U.S.C. 1531 et seq.). 

Rowan W. Gould, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2011–4121 Filed 2–23–11; 8:45 am] 

BILLING CODE 4310–55–P 

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. 

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: 


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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 mediumsized, 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. 


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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, landuse 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 


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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 overcollection (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, offroad vehicles, invasion by nonnative 

plants, livestock grazing, and overcollection (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-tosubstantial 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 (Soule ́ 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. 


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10314 Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 

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 


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Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 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 


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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 


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Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 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 

Nin ̃ 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 landuse 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 


emcdonald on DSK2BSOYB1PROD with PROPOSALS
10318 Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 

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, offroad 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 


emcdonald on DSK2BSOYB1PROD with PROPOSALS
Federal Register / Vol. 76, No. 37 / Thursday, February 24, 2011 / Proposed Rules 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, offroad 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 


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