78030 Federal Register / Vol. 75, No. 239 / Tuesday, December 14, 2010 / Proposed Rules 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R6–ES–2008–0029; MO 

92210–0–0008–B2] 

Endangered and Threatened Wildlife 

and Plants; 12-Month Finding on a 

Petition To List the North American 

Wolverine as Endangered or 

Threatened 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Notice of 12-month petition 

finding. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce a 

12-month finding on a petition to list 

the North American wolverine (Gulo 

gulo luscus) as an endangered or 

threatened species under the 

Endangered Species Act of 1973, as 

amended (Act). After review of all 

available scientific and commercial 

information, we find that the North 

American wolverine occurring in the 

contiguous United States is a distinct 

population segment (DPS) and that 

addition of this DPS to the Lists of 

Endangered and Threatened Wildlife 

and Plants is warranted. Currently, 

however, listing the contiguous U.S. 

DPS of the North American wolverine is 

precluded by higher priority actions to 

amend the Lists of Endangered and 

Threatened Wildlife and Plants. Upon 

publication of this 12-month petition 

finding, we will add the contiguous U.S. 

DPS of the wolverine to our candidate 

species list. We consider the current 

range of the species to include portions 

of the States of Washington, Idaho, 

Montana, Wyoming, Colorado, Utah, 

Oregon, and California. However, due to 

the dispersal abilities of individual 

wolverines, we expect that wolverines 

are likely to travel outside the currently 

occupied area. We will develop a 

proposed rule to list this DPS as our 

priorities allow (see section on 

Preclusion and Expeditious Progress). 

We will make any determination on 

critical habitat during development of 

the proposed listing rule. In the interim, 

we will address the status of this DPS 

through our annual Candidate Notice of 

Review. 

DATES: This finding was made on 

December 14, 2010. 

ADDRESSES: This finding is available on 

the Internet at http:// 

www.regulations.gov at Docket Number 

FWS–R6–ES–2008–0029. 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, Montana Field 

Office, U.S. Fish and Wildlife Service, 

585 Shepard Way, Helena, MT 59601; 

telephone (406) 449–5225. Please 

submit any new information, materials, 

comments, or questions concerning this 

finding to the above address. 

FOR FURTHER INFORMATION CONTACT: 

Mark Wilson, Field Supervisor, U.S. 

Fish and Wildlife Service, Montana 

Field Office (see ADDRESSES); by 

telephone at 406–449–5225; or by 

facsimile at 406–449–5339. If you use a 

telecommunications device for the deaf 

(TDD), call the Federal Information 

Relay Service (FIRS) at 800–877–8339. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 4(b)(3)(B) of the Act (16 

U.S.C. 1531 et seq.) requires that, for 

any petition to revise the Federal Lists 

of Endangered and Threatened Wildlife 

and Plants that contains substantial 

scientific and commercial information 

that listing a species may be warranted, 

we make a finding within 12 months of 

the date of receipt of the petition. In this 

finding, we determine whether the 

petitioned action is: (a) Not warranted, 

(b) warranted, or (c) warranted, but the 

immediate proposal of a regulation 

implementing the petitioned action is 

precluded by other pending proposals to 

determine whether species are 

threatened or endangered, and whether 

expeditious progress is being made to 

add or remove qualified species from 

the Federal Lists of Endangered and 

Threatened Wildlife and Plants. Section 

4(b)(3)(C) of the Act requires that we 

treat a petition for which the requested 

action is found to be warranted but 

precluded as though resubmitted on the 

date of such finding, that is, requiring a 

subsequent finding to be made within 

12 months. We must publish these 12- 

month findings in the Federal Register. 

Previous Federal Actions 

On April 19, 1995, we published a 

finding (60 FR 19567) that a previous 

petition, submitted by the Predator 

Project (now named the Predator 

Conservation Alliance) and Biodiversity 

Legal Foundation to list the wolverine 

in the contiguous United States, did not 

provide substantial information 

indicating that listing the wolverine in 

the contiguous United States may be 

warranted. 

On July 14, 2000, we received a 

petition dated July 11, 2000, submitted 

by the Biodiversity Legal Foundation, 

Predator Conservation Alliance, 

Defenders of Wildlife, Northwest 

Ecosystem Alliance, Friends of the 

Clearwater, and Superior Wilderness 

Action Network, to list the wolverine 

within the contiguous United States as 

a threatened or endangered species and 

designate critical habitat for the species. 

On October 21, 2003, we published a 

90-day finding that a petition to list the 

wolverine in the contiguous United 

States failed to present substantial 

scientific and commercial information 

indicating that listing may be warranted 

(68 FR 60112). 

On September 29, 2006, as a result of 

a complaint filed by Defenders of 

Wildlife and others alleging we used the 

wrong standards to assess the wolverine 

petition, the U.S. District Court, 

Montana District, ruled that our 90-day 

petition finding was in error and 

ordered us to make a 12-month finding 

for the wolverine. On April 6, 2007, a 

deadline for this 12-month finding was 

extended to February 28, 2008. 

On March 11, 2008, we published a 

12-month finding of ‘‘not warranted’’ for 

the wolverine in the contiguous United 

States (73 FR 12929). In that finding we 

determined that the wolverine in the 

contiguous United States did not 

constitute a distinct population segment 

or a significant portion of the range of 

wolverines in North America and so 

was not eligible for listing under the 

Act. 

On July 8, 2008 we received a Notice 

of Intent to Sue from Earthjustice 

alleging violations of the Act in our 

March 11, 2008, 12-month finding. On 

September 30, 2008, Earthjustice filed a 

complaint in the U.S. District Court, 

District of Montana, seeking to set aside 

and remand the 12-month finding back 

to the Service for reconsideration. 

On March 6, 2009, the Service agreed 

to settle the case with Earthjustice by 

voluntarily remanding the 12-month 

finding and issuing a new 12-month 

finding by December 1, 2010. Following 

the settlement agreement, the court 

dismissed the case on June 15, 2009, 

and ordered the Service to comply with 

the settlement agreement. 

On April 15, 2010, the Service 

published a Notice of Initiation of a 12- 

month finding for wolverines in the 

contiguous United States (75 FR 19591). 

Species Information 

Taxonomy and Life History 

The wolverine has a holarctic 

distribution including northern portions 

of Europe, Asia, and North America. 

The currently accepted taxonomy 

classifies wolverines worldwide as a 

single species, Gulo gulo. Old and New 

World wolverines are divided into 

separate subspecies. Wolverines in the 


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contiguous United States are a part of 

the New World subspecies, G. g. luscus: 

the North American wolverine (Kurten 

and Rausch 1959 p. 19; PasitschniakArts and Lariviere 1995, p. 1). The 

species is known by several common 

names including mountain devil, 

glutton, caracajou, quickhatch, gulon, 

skunk bear, as well as wolverine. 

The wolverine is the largest terrestrial 

member of the family Mustelidae. Adult 

males weigh 12 to 18 kilograms (kg) (26 

to 40 pounds (lb), and adult females 

weigh 8 to 12 kg (17 to 26 lb) (Banci 

1994, p. 99). The wolverine resembles a 

small bear with a bushy tail. It has a 

broad, rounded head; short, rounded 

ears, and small eyes. Each foot has five 

toes with curved, semi-retractile claws 

used for digging and climbing (Banci 

1994, p. 99). 

A large number of female wolverines 

(40 percent) are capable of giving birth 

at 2 years old, become pregnant most 

years, and produce litter sizes of 

approximately 3.4 kits on average. 

Pregnant females commonly resorb or 

spontaneously abort litters prior to 

giving birth (Magoun 1985, pp. 30–31; 

Copeland 1996, p. 43; Persson et al. 

2006, p. 77; Inman et al. 2007c, p. 70). 

It is likely that, despite the high rate of 

initiation of pregnancy, due to the 

spontaneous abortion of litters resulting 

from resource limitation, actual rates of 

successful reproduction in wolverines 

are among the lowest known for 

mammals (Persson 2005, p. 1456). In 

one study of known-aged females, none 

reproduced at age 2, 3 of 10 first 

reproduced at age 3, and 2 did not 

reproduce until age 4; the average age at 

first reproduction was 3.4 years (Persson 

et al. 2006, pp. 76–77). The average age 

at first reproduction is likely more than 

3 years (Inman et al. 2007c, p. 70). 

It is common for females to forgo 

reproducing every year, possibly saving 

resources to increase reproductive 

success in subsequent years (Persson 

2005, p. 1456). Supplemental feeding of 

females increases reproductive potential 

(Persson 2005, p. 1456). Foodsupplemented females were also more 

successful at raising kits to the time of 

weaning, suggesting that wolverine 

reproduction and ultimately population 

growth rates and viability are foodlimited. By age 3, nearly all female 

wolverines become pregnant every year, 

but energetic constraints due to low 

food availability result in loss of 

pregnancy in about half of them each 

year. It is likely that, in many places in 

the range of wolverines, it takes 2 years 

of foraging for a female to store enough 

energy to successfully reproduce 

(Persson 2005, p. 1456). 

Breeding generally occurs from late 

spring to early fall (Magoun and 

Valkenburg 1983, p. 175; Mead et al. 

1991, pp. 808–811). Females undergo 

delayed implantation until the 

following winter to spring, when active 

gestation lasts from 30 to 40 days 

(Rausch and Pearson 1972, pp. 254– 

257). Litters are born from mid-February 

through March, containing one to five 

kits, with an average in North America 

of between 1 and 2 kits (Magoun 1985, 

pp. 28–31; Copeland 1996, p. 36; Krebs 

and Lewis 1999, p. 698; Copeland and 

Yates 2006, pp. 32–36; Inman et al. 

2007c, p. 68). 

Female wolverines use natal (birthing) 

dens that are excavated in snow. 

Persistent, stable snow greater than 1.5 

meters (m) (5 feet (ft)) deep appears to 

be a requirement for natal denning, 

because it provides security for 

offspring and buffers cold winter 

temperatures (Pulliainen 1968, p. 342; 

Copeland 1996, pp. 92–97; Magoun and 

Copeland 1998, pp. 1317–1318; Banci 

1994, pp. 109–110; Inman et al. 2007c, 

pp. 71–72; Copeland et al. 2010, pp. 

240–242). Female wolverines go to great 

lengths to find secure den sites, 

suggesting that predation is a concern 

(Banci 1994, p. 107). Natal dens consist 

of tunnels that contain well-used 

runways and bed sites and may 

naturally incorporate shrubs, rocks, and 

downed logs as part of their structure 

(Magoun and Copeland 1998, pp. 1315– 

1316; Inman et al. 2007c, pp. 71–72). In 

Idaho, natal den sites occur above 2,500 

m (8,200 ft) on rocky sites, such as 

north-facing boulder talus or subalpine 

cirques in forest openings (Magoun and 

Copeland 1994, pp. 1315–1316). In 

Montana, natal dens occur above 2,400 

m (7,874 ft) and are located on north 

aspects in avalanche debris, typically in 

alpine habitats near timberline (Inman 

et al. 2007c, pp. 71–72). Offspring are 

born from mid-February through March, 

and the dens are typically used through 

late April or early May (Myrberget 1968, 

p. 115; Magoun and Copeland 1998, pp. 

1314–1317; Inman et al. 2007b, pp. 55– 

59). Occupation of natal dens is 

variable, ranging from approximately 9 

to 65 days (Magoun and Copeland 1998, 

pp. 1316–1317). 

Females may move kits to multiple 

secondary (maternal) dens as they grow 

during the month of May (Pulliainen 

1968, p. 343; Myrberget 1968, p. 115), 

although use of maternal dens may be 

minimal (Inman et al. 2007c, p. 69). 

Timing of den abandonment is related 

to accumulation of water in dens (due 

to snow melt), the maturation of 

offspring, disturbance, and geographic 

location (Myrberget 1968, p. 115; 

Magoun 1985, p. 73). After using natal 

and maternal dens, wolverines may also 

use rendezvous sites through early July. 

These sites are characterized by natural 

(unexcavated) cavities formed by large 

boulders, downed logs (avalanche 

debris), and snow (Inman et al. 2007c, 

p. 55–56). 

Habitat, Space, and Food 

In North America, wolverines occur 

within a wide variety of alpine, boreal, 

and arctic habitats, including boreal 

forests, tundra, and western mountains 

throughout Alaska and Canada. The 

southern portion of the species’ range 

extends into the contiguous United 

States, including high-elevation alpine 

portions of Washington, Idaho, 

Montana, Wyoming, California, and 

Colorado (Wilson 1982, p. 644; Hash 

1987, p. 576; Banci 1994, p. 102, 

Pasitschniak-Arts and Lariviere 1995, p. 

499; Aubry et al. 2007, p. 2152; Moriarty 

et al. 2009, entire; Inman et al. 2009, pp. 

22–25). Wolverines do not appear to 

specialize on specific vegetation or 

geological habitat aspects, but instead 

select areas that are cold and receive 

enough winter precipitation to reliably 

maintain deep persistent snow late into 

the warm season (Copeland et al. 2010, 

entire). The requirement of cold, snowy 

conditions means that, in the southern 

portion of the species’ range where 

ambient temperatures are warmest, 

wolverine distribution is restricted to 

high elevations, while at more northerly 

latitudes, wolverines are present at 

lower elevations and even at sea level in 

the far north (Copeland et al. 2010, 

Figure 1). 

In the contiguous United States, 

wolverines likely exist as a 

metapopulation (Aubry et al. 2007, p. 

2147, Figures 1, 3). A metapopulation is 

a network of semi-isolated populations, 

each occupying a suitable patch of 

habitat in a landscape of otherwise 

unsuitable habitat (Pulliam and 

Dunning 1997, pp. 212–214). 

Metapopulations require some level of 

regular or intermittent migration and 

gene flow among subpopulations, in 

which individual populations support 

one-another by providing genetic and 

demographic enrichment through 

mutual exchange of individuals (Meffe 

and Carroll 1997, p. 678). Individual 

subpopulations may go extinct or lose 

genetic viability, but are then ‘‘rescued’’ 

by immigration from other 

subpopulations, thus ensuring the 

persistence of the metapopulation as a 

whole. Metapopulation dynamics (the 

process of extinction and recolonization 

by subpopulations) rely on the ability of 

subpopulations to support one another 

through exchange of individuals for 

genetic and demographic enrichment. If 


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metapopulation dynamics break down, 

either due to changes within 

subpopulations or loss of connectivity, 

then the entire metapopulation may be 

jeopardized due to subpopulations 

becoming unable to persist in the face 

of inbreeding or demographic and 

environmental stochasticity (Pulliam 

and Dunning 1997b, pp. 221–222). We 

believe this outcome is likely for 

wolverine, due to their naturally low 

reproductive rates and low densities. 

Wolverines are opportunistic feeders 

and consume a variety of foods 

depending on availability. They 

primarily scavenge carrion, but also 

prey on small animals and birds, and eat 

fruits, berries, and insects (Hornocker 

and Hash 1981, p. 1290; Hash 1987, p. 

579; Banci 1994, pp. 111–113). 

Wolverines have an excellent sense of 

smell that enables them to find food 

beneath deep snow (Hornocker and 

Hash 1981, p. 1297). 

Wolverines require a lot of space; the 

availability and distribution of food is 

likely the primary factor in determining 

wolverine movements and home range 

size (Hornocker and Hash 1981, p. 1298; 

Banci 1994, pp. 117–118). Female 

wolverines forage close to den sites in 

early summer, progressively ranging 

further from dens as kits become more 

independent (May et al. 2010, p. 941). 

Wolverines travel long distances over 

rough terrain and deep snow, and adult 

males generally cover greater distances 

than females (Hornocker and Hash 1981, 

p. 1298; Banci 1994, pp. 117–118; 

Moriarty et al. 2009, entire; Inman et al. 

2009, pp. 22–28; Brian 2010, p. 3; 

Copeland and Yates 2006, Figure 9). 

Home ranges of wolverines are large, 

and vary greatly in size depending on 

availability of food, gender and age of 

the animal, and differences in habitat 

quality. Home ranges of adult 

wolverines also vary in size depending 

on geographic location. Home ranges in 

Alaska were approximately 100 square 

kilometers (km2) to over 900 km2 (38.5 

square miles (mi2) to 348 mi2) (Banci 

1994, p. 117). Average home ranges of 

resident adult females in central Idaho 

were 384 km2 (148 mi2), and average 

home ranges of resident adult males 

were 1,522 km2 (588 mi2) (Copeland 

1996, p. 50). Wolverines in Glacier 

National Park had average adult male 

home ranges of 496 km2 (193 mi2) and 

adult female home ranges of 141 km2

(55 mi2) (Copeland and Yates 2006, p. 

25). Wolverines in the Greater 

Yellowstone Ecosystem had average 

adult male home ranges of 797 km2 (311 

mi2), and average adult female home 

ranges of 329 km2 (128 mi2) (Inman et 

al. 2007a, p. 4). These home range sizes 

are large relative to the body size of 

wolverines, and may indicate that 

wolverines occupy a relatively 

unproductive niche in which they must 

forage over large areas to consume the 

amount of calories needed to meet their 

life-history requirements (Inman et al. 

2007a, p. 11). 

Wolverine Densities 

Wolverines naturally occur in low 

densities of about 1 wolverine per 150 

km2 (58 mi2) with a reported range from 

1 per 65 to 337 km2 (25 to 130 mi2) 

(Hornocker and Hash 1981, pp. 1292– 

1295; Hash 1987, p. 578; Copeland 

1996, pp. 31–32; Copeland and Yates 

2006, p. 27; Inman et al. 2007a, p. 10; 

Squires et al. 2007, p. 2218). No 

systematic population census exists 

over the entire current range of 

wolverines in the contiguous United 

States, so the current population level 

and trends remain unknown. However, 

based on our current knowledge of 

occupied wolverine habitat and 

wolverine densities in this habitat, it is 

reasonable to estimate that the 

wolverine population in the contiguous 

United States numbers approximately 

250 to 300 individuals (Inman 2010b, 

pers. comm.). The bulk of the current 

population occurs in the northern Rocky 

Mountains with a few individuals in the 

North Cascades and one known 

individual each in the Sierra Nevada 

and southern Rocky Mountains. Within 

the area known to currently have 

wolverine populations relatively few 

wolverines can coexist due to their 

naturally low population densities, even 

if all areas were occupied at or near 

carrying capacity. Given the natural 

limitations on wolverine population 

density, it is likely that historic 

wolverine population numbers were 

also low (Inman et al. 2007a, Table 6). 

Because of these natural limitations, we 

believe that densities and population 

levels in the northern Rocky Mountains 

and North Cascades where populations 

currently exist are likely not 

substantially lower than population 

densities were in these areas prior to 

European settlement. However, 

historically, the contiguous U.S. 

population would have been larger than 

it is today due to the larger area 

occupied by populations when the 

southern Rocky Mountains and Sierra 

Nevada were occupied at full capacity. 

Wolverine Status in Canada and Alaska 

The bulk of the range of North 

American wolverines is found in 

Canada and Alaska. Wolverines inhabit 

alpine tundra, boreal forest, and arctic 

habitats in Canada and Alaska (Slough 

2007, p. 78). Wolverines in Canada have 

been divided into two populations for 

management by the Canadian 

Government: An eastern population in 

Labrador and Quebec, and a western 

population that extends from Ontario to 

the Pacific coast, and north to the Arctic 

Ocean. The eastern population is 

currently listed as endangered under the 

Species At Risk Act in Canada, and the 

western population is designated as a 

species of special concern (COSEWIC 

2003, p. 8). 

The current status of wolverines in 

eastern Canada is uncertain. Wolverines 

have not been confirmed to occur in 

Quebec since 1978 (Fortin et al. 2005, p. 

4). Historical evidence of wolverine 

presence in eastern Canada is also 

suspect because no proof exists to show 

that wolverine pelts attributed to 

Quebec or Labrador actually came from 

that region; animals were possibly 

trapped elsewhere and the pelts shipped 

through the eastern provinces 

(COSEWIC 2003, p. 20). Wolverines in 

eastern Canada may currently exist in 

an extremely low-density population, or 

may be extirpated. Wolverines in 

eastern Canada, both historically and 

currently, could represent migrants from 

western populations that never became 

resident animals (COSEWIC 2003, pp. 

20–21). The Federal Government of 

Canada has completed a recovery plan 

for the eastern population with the goal 

of establishing a self-sustaining 

population through reintroduction and 

protection (Fortin et al. 2005, p. 16). 

Wolverines in western Canada and 

Alaska inhabit a variety of habitats from 

sea level to high in mountains (Slough 

2007, pp. 77–78). They occur in Ontario, 

Manitoba, Saskatchewan, Alberta, 

British Columbia, Yukon, Northwest 

Territories, and Nunavut (Slough 2007, 

pp. 77–78). Since European 

colonization, a generally recognized 

range contraction has taken place in 

boreal Ontario and the aspen parklands 

of Manitoba, Saskatchewan, and Alberta 

(COSEWIC 2003, pp. 20–21; Slough 

2007, p. 77). This range contraction 

occurred concurrently with a reduction 

in wolverine records for the Great Lakes 

region in the contiguous United States 

(Aubry et al. 2007, pp. 2155–2156). 

Causes of these changes are uncertain, 

but may be related to increased harvest, 

habitat modification, or climate change 

(COSEWIC 2003, pp. 20–21; Aubry et al. 

2007, pp. 2155–2156; Slough 2007, pp. 

77–78). Analysis supports climate 

change as a contributing factor to 

declines in southern Ontario, because 

snow conditions necessary to support 

wolverines do not currently exist in the 

Great Lakes region of the contiguous 

United States, and are marginal in 

southern Ontario (Aubry et al. 2007, p. 

2154). It is not known if these snow 


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conditions existed historically in the 

Great Lakes of the contiguous United 

States, however, the small number of 

wolverine records from this area 

suggests that they did not. It is possible 

that suitable snow conditions did reach 

further south in eastern Canada in 1850 

than they do today, making wolverine 

dispersal attempts from Canada to the 

Great Lakes region of the contiguous 

United States more likely than they are 

now. Wolverines occurred historically 

on Vancouver Island and have been 

given status as a separate subspecies by 

some (Hall 1981, p. 109). The 

Vancouver Island population is now 

regarded as possibly extirpated; no 

sightings have occurred since 1992 

(COSEWIC 2003, p. 18). 

Wolverines in western Canada and 

Alaska appear to persist everywhere that 

habitat and climate conditions are 

suitable (COSEWIC 2003, pp. 13–21; 

Aubry et al. 2007, pp. 2152–2155; 

Slough 2007, p. 79; Copeland et al. 

2010, Figure 2). Throughout this area, 

wolverines are managed by regulated 

harvest at the Provincial and State level. 

Population estimates for Canada and 

Alaska are rough because no wolverine 

surveys have taken place at the State or 

Provincial scale. However, the 

population in western Canada is 

estimated to include approximately 

15,089 to 18,967 individuals (COSEWIC 

2003, p. 22). The number of wolverines 

in Alaska is unknown, but they appear 

to exist at naturally low densities in 

suitable habitats throughout Alaska 

(Alaska Department of Fish and Game 

2004, pp. 1–359). We have no 

information to indicate that wolverine 

populations have been reduced in 

numbers or geographic range in Alaska. 

The Complexity of Geographic Range 

Delineation 

Delineating wolverine historical and 

present range is inherently difficult for 

several reasons. Wolverines tend to live 

in remote and inhospitable places away 

from human populations where they are 

seldom encountered, documented, or 

studied. Wolverines naturally occur at 

low population densities and are rarely 

and unpredictably encountered where 

they do occur. Wolverines often move 

long distances in short periods of time, 

when dispersing from natal ranges, into 

habitats that are unsuitable for longterm survival (Aubry et al. 2007, p. 

2147; Moriarty et al. 2009, entire; Inman 

et al. 2009, pp. 22–28; Brian 2010, p. 3). 

Such movements make it difficult to 

distinguish with certainty between 

occurrence records that represent 

established populations and those that 

represent short-term occupancy or 

exploratory movements without the 

potential for establishment of home 

ranges, reproduction, and eventually 

populations. These natural attributes of 

wolverines make it difficult to precisely 

determine their present range, or trends 

in range expansion or contraction that 

may have occurred in the past. 

Therefore, we must be cautious and use 

multiple lines of evidence when trying 

to determine where past wolverine 

populations occurred. 

Throughout the remainder of this 

finding, we focus on the use of 

verifiable and documented wolverine 

occurrence records to define historic 

and present range because we have 

determined that these records constitute 

the best scientific information available 

on the past and present distribution of 

wolverines (See Aubry et al. 2007, p. 

2148). Verifiable records are records 

supported by physical evidence such as 

museum specimens, harvested pelts, 

DNA samples, and diagnostic 

photographs. Documented records are 

those based on accounts of wolverines 

being killed or captured. Use of only 

verifiable and documented records 

avoids mistakes of misidentification 

often made in eyewitness accounts of 

visual encounters. Visual-encounter 

records often represent the majority of 

occurrence records for elusive forest 

carnivores, and their inherently high 

rate of misidentification of the species 

involved can result in wildly inaccurate 

conclusions about species occurrence 

(McKelvey et al. 2008, entire). The 

paper by Aubry et al. (2007, entire) 

utilized only verifiable and documented 

records to investigate wolverine 

distribution through time. This paper is 

the only available comprehensive 

treatment of these distribution patterns 

that attempts to distinguish between 

records that represent resident animals 

versus animals that have dispersed 

outside of suitable habitat. For these 

reasons we believe that Aubry et al. 

(2007, entire) represents the best 

available summary of wolverine 

occurrence records in the contiguous 

United States at this time. Since the 

publication of Aubry et al. (2007, 

entire), verified records of wolverine 

have also been documented in Colorado 

and California, which we will describe 

in greater detail below. 

Aubry et al. (2007, entire) used 

verifiable and documented records from 

museum collections, literature sources, 

and State and Federal institutions to 

trace changes in geographic distribution 

of wolverines in the historic record. 

They then used an overlay of suitable 

wolverine habitats to further refine 

which records represent wolverines in 

habitats that may support residency, 

and by extension, populations, and 

which records likely represent 

wolverines outside the range of suitable 

habitats, so called ‘‘extralimital’’ records. 

Aubry et al.’s (2007, entire) focus on 

verifiable and documented records 

corrected past overly broad approaches 

to wolverine range mapping (Nowak 

1973, p. 22; Hall 1981, p. 1009; Wilson 

1982, p. 644; Hash 1987, p. 576) that 

used a more inclusive but potentially 

misleading approach when dealing with 

occurrence records. Many of the 

extralimital records used in these 

publications represent individuals 

dispersing from natal ranges that ended 

up in habitats that cannot support 

wolverines, and the use of this data to 

determine the historic geographic range 

of wolverines results in gross 

overestimation of the area that can 

actually be used successfully by 

wolverines for the establishment of 

populations. Subsequent to publication 

of Aubry et al. (2007, entire), Copeland 

et al. (2010, entire) further refined our 

understanding of wolverine habitat 

needs and corroborated the approach of 

Aubry et al. (2007, entire). 

We agree with Aubry et al. (2007, p. 

2149) that the most appropriate method 

to determine the current and historic 

range of wolverines is to use a 

combination of occurrence records and 

habitat suitability, along with other 

information, such as documented 

successful reproduction events, that 

indicate where reproductive and 

potentially self-sustaining populations 

may occur. We also generally agree with 

their conclusions about the historic and 

current range of the species. We believe 

that the species’ range is the area that 

may support viable populations, and 

does not include extralimital 

occurrences outside of habitat that is 

likely to support wolverine life-history 

needs. Areas that can support wolverine 

populations may be referred to as 

potential ‘‘source’’ populations because 

they provide surplus individuals 

through reproduction beyond what is 

needed for replacement. Areas that do 

not have the habitat to support viable 

populations may be referred to as 

population ‘‘sinks’’ because wolverines 

may disperse to these areas and remain 

for some time, but will either die there 

without reproducing, leave the area in 

search of better habitat conditions, or 

may actually reproduce, but at a rate 

lower than that needed for replacement 

of individuals lost to mortality or 

emigration, leading to eventual 

population extinction. For a widely 

dispersing species like wolverines, we 

expect many locality records to 

represent dispersers into sink habitats. 

The value to the population (and thus 


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the DPS) of these dispersers in sink 

habitat is unclear; however, it is likely 

that most dispersers into sink habitats 

will be lost to the population unless 

they are able to move back into source 

habitats. Therefore, it is our belief that 

population sink areas, here defined as 

places where wolverines may be found 

but where habitat is not suitable for 

long-term occupancy and reproduction, 

do not represent part of the species 

historic range and have little 

conservation value for the DPS, other 

than possibly serving as way-stations for 

attempted dispersers as they search for 

suitable habitats. This approach to 

defining historic range results in 

reducing the bias of extralimital 

dispersers and concentrates 

conservation attention on areas capable 

of maintaining populations, and is more 

in keeping with the intentions of the 

Act, than broader depictions of 

geographic range. 

Aubry et al. (2007, pp. 2147–2148) 

divided records into ‘‘historical’’ 

(recorded prior to 1961), ‘‘recent’’ 

(recorded between 1961 and 1994), and 

‘‘current’’ (recorded after 1994). 

Historical records occurred before 

systematic surveys. Historical records 

encompass the time during which 

wolverine numbers and distribution 

were hypothesized to be at their highest 

(prior to European settlement) and also 

at their lowest (early 20th Century) 

(Wright and Thompson 1935; Grinnell 

et al. 1937; Allen 1942; Newby and 

Wright 1955, all as cited in Aubry et al. 

2007, p. 2148). The recent time interval 

covers a hypothesized population 

expansion and rebound from the early 

20th Century low. Current records offer 

the most recent evidence available for 

wolverine occurrences and potential 

populations. We believe all occurrence 

records must be individually analyzed 

in light of their context in terms of 

habitat conditions conducive to 

wolverine population establishment and 

whether or not they occur clustered 

with other records, which might 

indicate that populations have 

historically occurred in the area. The 

authors of Aubry et al. (2007) did such 

an analysis as they compiled their 

records. 

Wolverine Distribution 

Of 729 mappable records (those 

records with precise location 

information) compiled by Aubry et al. 

(2007, p. 2150), 188 were from the 

historical time interval (see Figure 1). 

We assessed the historical, recent, and 

current distribution data for each of the 

regions below to determine the 

likelihood of the presence of historical 

populations (rather than extralimital 

dispersers). The discussion below draws 

heavily from both Aubry et al. (2007, 

entire) and Copeland et al. (2010, 

entire). 

TABLE 1—WOLVERINE RECORDS FROM THREE TIME PERIODS FROM AUBRY ET AL. 2007. 

[Numbers Represent Total Documented and Verifiable Records With the Subset of Those Records That Were Verifiable in Parentheses] 

Historical 

(< 1964) 

Recent 

(1961–1994) 

Current 

(> 1994) 

Northeast ..................................................................................................................................... 13 (1) 0 0 

Upper Midwest ............................................................................................................................. 4 (2) 0 0 

Great Lakes ................................................................................................................................. 36 (4) 1 0 

Central Great Plains .................................................................................................................... 71 * (2) 1 0 

Rocky Mountains ......................................................................................................................... 147 (45) 332 (283) 215 (210) 

Pacific Coast ................................................................................................................................ 89 (14) 23 (15) 7 

Totals .................................................................................................................................... 362 (68) 357 (298) 222 (210) 

* 35 records from a single source (the journals of Alexander Henry). 

Northeast and Upper Midwest—The 

low number of records and scattered 

nature of their distribution combined 

with a lack of suitable habitat indicate 

that wolverines were likely only 

occasional transients to the area and not 

present as a reproducing population 

after 1800. 

Great Lakes—The lack of large 

numbers of verifiable records in this 

area of relatively high human 

population density and the lack of 

suitable habitat suggests that wolverines 

did not exist in this area as a viable 

population after 1900. Widely scattered 

records generally before 1900, with an 

occasional record after that year, suggest 

that if a reproducing population existed 

in the Great Lakes, it predated 1900, and 

that post-1900 records represent 

dispersal from a receding Canadian 

population. Wolverine distribution in 

Ontario, Canada, appears to have 

receded north from the Great Lakes 

region since the 1800s, and currently 

wolverines occupy only the northern 

portion of the province, a distance of 

over 400 miles from the U.S. border 

(COSEWIC 2003, p. 9). The pattern of 

record distribution illustrated in Aubry 

et al. (2007, p. 2152) is consistent with 

what would be expected if those records 

were of dispersing individuals from a 

Canadian population that receded 

progressively further north into Canada 

after 1900, possibly due to natural 

climate changes. 

Central Great Plains—The lack of 

precise locality records and suitable 

habitat from the Great Plains States 

leads us to conclude that reproducing 

populations of wolverines did not 

historically inhabit this area. Thirty-five 

of thirty-six records from North Dakota 

are from the journals of a single fur 

trader (see Table 1), and it is not clear 

that the records represent actual 

collection localities or are localities 

where trades or shipments occurred 

(Aubry 2007, pers. comm.). Given the 

habitat relationships of wolverines (e.g., 

Copeland et al. 2010, Figure 1), it is 

unlikely that these records represent 

established wolverines or that this area 

was in any way wolverine habitat. 

Rocky Mountains—Five Rocky 

Mountains States (Idaho, Montana, 

Wyoming, Colorado, and Utah) 

contained numerous wolverine records. 

Records with precise locality 

information appear to coalesce around 

several areas that may have been 

population centers, such as central 

Colorado, the greater Yellowstone 

region, and northern Idahonorthwestern Montana. The large 

number of verifiable and documented 

records for this region, along with the 

suggestion of population centers or 

strongholds, suggests that wolverines 

existed in reproducing populations 

throughout much of the Rocky 

Mountains during the historical time 

interval. The lack of records for 

Colorado and Utah after 1921 suggests 

that the southern Rocky Mountain 

population of wolverines was extirpated 

in the early 1900s, concurrent with 


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widespread systematic predator control 

by government agencies and livestock 

interests. The northern Rocky Mountain 

population (north of Wyoming) was 

reduced to historic lows or possibly 

even extirpated during the early 1900s, 

and then increased dramatically in the 

second half of the 1900s (see Table 1) 

as predator control efforts subsided and 

trapping regulations became more 

restrictive (Aubry et al. 2007, p. 2151). 

This increase likely indicates a 

population rebound from historic lows 

in this period. 

Wolverine records from 1995 to 2005 

indicate that wolverine populations 

currently exist in the northern Rocky 

Mountains (see Table 1). Legal trapping 

in Montana in the recent past removed 

an average of 10.5 individuals from this 

population each year (Montana 

Department of Fish, Wildlife, and Parks 

2007, p. 2), and harvest mortality has 

been reduced due to regulatory changes 

in 2008 (Montana Department of Fish, 

Wildlife and Parks 2008, p. 8). 

Populations in British Columbia and 

Alberta, Canada, are extant (COSEWIC 

2003, pp. 18–19), and may have been a 

source of surplus wolverines to the 

contiguous U.S. population during 

population lows. Recently, a male 

wolverine moved on its own from the 

southern Greater Yellowstone Area of 

Wyoming into the southern Rocky 

Mountains of Colorado where it still 

persisted as of August 2010 (Inman et al. 

2009, pp. 22–26; Inman 2010, pers. 

comm.). This attempted dispersal event 

is the first verified wolverine occurrence 

in Colorado since 1919 and may 

represent a continuation of the 

wolverine expansion in the Rocky 

Mountains detailed above. It is possible 

that other wolverines have travelled to 

the southern Rocky Mountains and have 

remained undetected. There is no 

evidence that Colorado currently hosts a 

wolverine population or that female 

wolverines have made, or are likely to 

make, similar movements. 

Pacific Coast—Historically, 

wolverines occurred in two population 

centers in the North Cascades Range and 

the Sierra Nevada. These areas are 

separated by an area with no historic 

records (southern Oregon and northern 

California), indicating that the historical 

distribution of wolverines in this area is 

best represented by two disjunct 

populations rather than a continuous 

peninsular extension from Canada. This 

conclusion is supported by genetic data 

indicating that the Sierra Nevada and 

Cascades wolverines were separated for 

at least 2,000 years prior to extirpation 

of the Sierra Nevada population 

(Schwartz et al. 2007, p. 2174). 

Only one Sierra Nevada record exists 

after 1930, indicating that this 

population was likely extirpated in the 

first half of the 1900s concurrent with 

widespread systematic predator control 

programs. In 2008, a male wolverine 

was discovered in the Sierra Nevada 

Range of California, the first verified 

record from California since 1922 

(Moriarty et al. 2009, entire). Genetic 

testing revealed that this wolverine was 

not a descendant of the endemic Sierra 

Nevada wolverine population, but was 

likely derived from wolverines in the 

Rocky Mountains (Moriarty et al. 2009, 

p. 159). This attempted dispersal event 

may represent a continuation of the 

wolverine expansion in the contiguous 

United States as detailed above. Other 

wolverines may have traveled to the 

Sierra Nevada and remain undetected. 

There is no evidence that California 

currently hosts a wolverine population 

or that female wolverines have made or 

are likely to make similar dispersal 

movements. 

Wolverines were likely extirpated 

from the North Cascades in the early 

20th century and then recently 

recolonized from Canada. Currently, a 

small population persists in this area 

(Aubrey et al. 2009, entire). The 

Northern Cascades population may be 

connected with, and is possibly 

dependent on, the larger Canadian 

population for future expansion and 

long-term persistence. 

Summary of Wolverine Distribution 

Historical wolverine records were 

found across the northern tier of the 

contiguous United States with 

convincing evidence of wolverine 

populations in the northern and 

southern Rocky Mountains, Sierra 

Nevada Mountains, and North Cascades 

Mountains (Aubry et al. 2007, p. 2152). 

Currently, wolverines appear to be 

distributed as functioning populations 

in two regions in the contiguous United 

States: The North Cascades in 

Washington, and the northern Rocky 

Mountains in Idaho, Montana, and 

Wyoming. Wolverines were likely 

extirpated, or nearly so, from the entire 

contiguous United States in the first half 

of the 20th Century (Aubry et al. 2007, 

Table 1). The available evidence 

suggests that, in the second half of the 

20th Century and continuing into the 

present time, wolverine populations 

have expanded in the North Cascades 

and the northern Rocky Mountains, but 

that populations have not been 

reestablished in the Sierra Nevada 

Range or the southern Rocky Mountains. 

We conclude that the current range of 

the species in the contiguous United 

States includes the North Cascades 

Mountains, the northern Rocky 

Mountains, the southern Rocky 

Mountains, and the Sierra Nevada 

Mountains, but that reestablishment of 

populations in the southern Rocky 

Mountains and Sierra Nevada has not 

yet occurred. 

We also conclude that wolverines 

either did not exist as established 

populations, or were extirpated prior to 

settlement and the compilation of 

historical records, in the Great Lakes 

region, possibly due to climate changes 

that occurred through the 1800s and 

1900s. The Great Lakes region lacks 

suitable wolverine habitat, and suitable 

habitat does not appear to exist in 

adjacent Canada (Copeland et al. 2010, 

Figure 1). The widely scattered records 

from this region are consistent with 

dispersing individuals from a Canadian 

population that receded north early in 

the 1800s. We cannot rule out the 

possibility that wolverines existed as 

established populations prior to the 

onset of trapping in this area, but we 

have no reliable evidence that they did. 

No reliable evidence in the historical 

records indicates that wolverines were 

ever present as established populations 

in the Great Plains, Midwest, or 

Northeast. 

Habitat Relationships and Wolverine 

Distribution 

Deep, persistent, and reliable spring 

snow cover (April 15 to May 14) is the 

best overall predictor of wolverine 

occurrence in the contiguous United 

States (Aubry et al. 2007, pp. 2152– 

2156; Copeland et al. 2010, entire). Deep 

persistent snow correlates well with 

wolverine year-round habitat use across 

wolverine distribution in North America 

and Eurasia at both regional and local 

scales (Copeland et al. 2010, entire). It 

is uncertain why spring snow cover so 

accurately predicts wolverine habitat 

use; however, it is likely related to 

wolverines’ need for deep snow during 

the denning period, and also 

wolverines’ physiological requirement 

for year-round cold temperatures 

(Copeland et al. 2010, pp. 242–243). 

Snow cover during the denning period 

is essential for successful wolverine 

reproduction range-wide (Hatler 1989, 

p. iv; Magoun and Copeland 1998, p. 

1317; Inman et al. 2007c, pp. 71–72; 

Persson 2007; Copeland et al. 2010, p. 

244). Wolverine dens tend to be in areas 

of high structural diversity such as logs 

and boulders with deep snow (Magoun 

and Copeland 1998, p. 1317; Inman et 

al. 2007c, pp. 71–72; Persson 2007, 

entire). Reproductive females dig deep 

snow tunnels to reach the protective 

structure provided by logs and boulders. 

This behavior presumably protects the 


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vulnerable kits from predation by large 

carnivores, including other wolverines 

(Pulliainen 1968, p. 342; Zyryanov 

1989, pp. 3–12), but may also have 

physiological benefits for kits by 

buffering them from extreme cold, wind, 

and desiccation (Pullianen 1968, p. 342, 

Bja ̈rvall et al. 1978, p. 23). Wolverines 

live in low-temperature conditions and 

appear to select habitats in part to avoid 

high summer temperatures (Copeland et 

al. 2010, p. 242). Wolverine distribution 

is likely affected by climatic conditions 

at two different scales. Wolverines 

require deep persistent snow for 

denning, and this likely determines 

where wolverine populations can be 

found at the grossest range-wide scale 

(Copeland et al. 2010, p. 244). At 

smaller scales, wolverines likely select 

habitats to avoid high summer 

temperatures. These cool habitats also 

tend to retain snow late into spring, 

leading to wolverines’ year-round 

association with areas of persistent 

spring snow (Copeland et al. 2010, p. 

244). 

All of the areas in the contiguous 

United States for which good evidence 

of persistent wolverine populations 

(either present or historic) exists (i.e., 

North Cascades, Sierra Nevada, northern 

and southern Rocky Mountains) contain 

large and well-distributed areas of deep 

snow cover that persists through the 

wolverine denning period (Brock et al. 

2007, pp. 36–53; Aubry et al. 2007, p. 

2154; Copeland et al. 2010, Figure 1). 

The Great Plains, Great Lakes, Midwest, 

and Northeast lack the spring snow 

conditions and low summer 

temperatures thought to be required by 

wolverines for successful reproduction 

and year-round occupancy (Aubry et al. 

2007, p. 2154; Copeland et al. 2010, 

Figure 1). The lack of persistent spring 

snow conditions in the Great Plains, 

Great Lakes, Midwest, and Northeast 

supports the exclusion of these areas 

from the current range of wolverines. 

Whether wolverines once existed as 

established populations in any of these 

regions is uncertain, but the current 

climate appears to preclude their 

presence as reproducing populations 

now, and the sparse historical record of 

wolverine presence in this area makes 

historic occupation of these areas by 

wolverine populations doubtful. It is 

our conclusion that the ecosystem that 

supports wolverines does not exist in 

these areas currently, and may never 

have existed in the past. 

Large areas of habitat with 

characteristics suitable for wolverines 

still occur in the southern Rocky 

Mountains and Sierra Nevada, despite 

the extirpation of wolverines from those 

areas (Aubry et al. 2007, p. 2154, Brock 

et al. 2007, p. 26; Copeland et al. 2010, 

Figure 1). Wolverine extirpations in 

these areas were coincident with 

systematic predator eradication efforts 

in the early 1900s, which have been 

discontinued for many years. Each of 

these areas has received at least one and 

possibly more migrants from adjacent 

populations in the northern Rocky 

Mountains; however, there is no 

evidence that females have migrated to 

these areas or that populations of 

wolverines exist in them (Aubry et al. 

2007, Table 1; Moriarty et al. 2009, 

entire; Inman et al. 2009, entire). 

We conclude that areas of wolverine 

historical occurrence can be placed in 

one of three categories: (1) Areas where 

wolverines are extant as reproducing 

and potentially self-sustaining 

populations (North Cascades, northern 

Rocky Mountains); (2) areas where 

wolverines historically existed as 

reproducing and potentially selfsustaining populations prior to humaninduced extirpation, and where 

reestablishment of those populations is 

possible given current habitat condition 

and management (the Sierra Nevada 

Mountains in California and southern 

Rocky Mountains in Colorado, New 

Mexico, Wyoming, and Utah); and (3) 

areas where historical presence of 

wolverines in reproducing and 

potentially self-sustaining populations 

is doubtful, and where the current 

habitat conditions preclude the 

establishment of populations (Great 

Plains, Midwest, Great Lakes, and 

Northeast). We, therefore, consider the 

current range of wolverines to include 

suitable habitat in the North Cascades of 

Washington and possibly Oregon, the 

northern Rocky Mountains of Idaho, 

Wyoming, and Montana, the southern 

Rocky Mountains of Colorado, Utah, 

and Wyoming, and the Sierra Nevada of 

California. We here include the Sierra 

Nevada and southern Rocky Mountains 

in the current range of wolverines 

despite the probability that functional 

populations do not exist in these areas. 

They are included due to the known 

existence of one individual in each area 

and the possibility that more, as yet 

undetected, individuals inhabit these 

areas. 

Distinct Population Segment 

Pursuant to the Act, we must consider 

for listing any species, subspecies, or, 

for vertebrates, any Distinct Population 

Segment (DPS) of these taxa, if there is 

sufficient information to indicate that 

such action may be warranted. To 

interpret and implement the DPS 

provision of the Act and Congressional 

guidance, the Service and the National 

Marine Fisheries Service published, on 

February 7, 1996, an interagency Policy 

Regarding the Recognition of Distinct 

Vertebrate Population Segments under 

the Act (61 FR 4722). This policy 

addresses the recognition of DPSs for 

potential listing actions. The policy 

allows for more refined application of 

the Act that better reflects the biological 

needs of the taxon being considered, 

and avoids the inclusion of entities that 

do not require its protective measures. 

Under our DPS policy, three elements 

are considered in a decision regarding 

the status of a possible DPS as 

endangered or threatened under the Act. 

These are applied similarly for 

additions to the list of endangered and 

threatened species, reclassification, and 

removal from the list. They are: (1) 

Discreteness of the population segment 

in relation to the remainder of the taxon; 

(2) the biological or ecological 

significance of the population segment 

to the taxon to which it belongs; and (3) 

the population segment’s conservation 

status in relation to the Act’s standards 

for listing (i.e., whether the population 

segment is, when treated as if it were a 

species or subspecies, endangered or 

threatened). Discreteness refers to the 

degree of isolation of a population from 

other members of the species, and we 

evaluate this based on specific criteria. 

If a population segment is considered 

discrete, we must consider whether the 

discrete segment is ‘‘significant’’ to the 

taxon to which it belongs by using the 

best available scientific and commercial 

information. If we determine that a 

population segment is both discrete and 

significant, we then evaluate it for 

endangered or threatened status based 

on the Act’s standards. The DPS 

evaluation in this finding concerns the 

segment of the wolverine species 

occurring within the 48 States, 

including the northern and southern 

Rocky Mountain physiographic 

provinces, Sierra Nevada Range, and 

North Cascades Range. 

Distinct Population Segment Analysis 

for Wolverine in the Contiguous United 

States 

Analysis of Discreteness 

Under our DPS Policy, a population 

segment of a vertebrate species may be 

considered discrete if it satisfies either 

one of the following conditions: (1) It is 

markedly separated from other 

populations of the same taxon as a 

consequence of physical, physiological, 

ecological, or behavioral factors 

(quantitative measures of genetic or 

morphological discontinuity may 

provide evidence of this separation); or 

(2) it is delimited by international 

governmental boundaries within which 


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differences in control of exploitation, 

management of habitat, conservation 

status, or regulatory mechanisms exist 

that are significant in light of section 

4(a)(1)(D) of the Act (inadequacy of 

existing regulatory mechanisms). The 

wolverine within the contiguous United 

States meets the second DPS 

discreteness condition because of 

differences in conservation status as 

delimited by the Canadian-U.S. 

international governmental boundary. 

Discreteness Based on the International 

Border—Differences in Conservation 

Status 

We find that differences in 

conservation status of the wolverine 

between the United States and Canada 

are substantial and significant in light of 

section 4(a)(1)(D) of the Act. In the 

remaining current range in CanadaAlaska, wolverines exist in welldistributed, interconnected, large 

populations. Conversely, wolverine 

populations in the remaining U.S. range 

appear to be at numbers so low that 

their continued existence could be at 

risk, especially as considered in light of 

the five threat factors discussed below. 

These risks come from three main 

factors: (1) Small total population size; 

(2) effective population size below that 

needed to maintain genetic diversity 

and demographic stability; and (3) the 

fragmented nature of wolverine habitat 

in the contiguous United States that 

results in smaller, isolated ‘‘sky island’’ 

patches separated by unsuitable 

habitats. It is apparent that maintaining 

wolverines within their native range in 

the contiguous United States into the 

future is likely to require regulatory 

mechanisms that are not currently in 

place. These three factors are explained 

in more detail below. 

The total population sizes for CanadaAlaska and the contiguous United States 

differ by more than an order of 

magnitude. The contiguous U.S. 

population likely numbers 

approximately 250 to 300 individuals 

(Inman 2010b, pers. comm.). This 

contrasts with western Canada, where 

wolverine populations are estimated at 

15,089 to 18,967 individuals (COSEWIC 

2003, p. 22). Wolverine population size 

in Alaska is unknown; however, the 

average annual harvest exceeds 500 

individuals and the population does not 

appear to be in decline (Alaska 

Department of Fish and Game 2004, 

entire), indicating that the population is 

likely to number over ten thousand 

individuals (calculated using 

demographic data in Lofroth and Ott 

2007, pp. 2196–2198; assumes 

sustainable harvest). The difference in 

total population size coincides with the 

international boundary between the 

contiguous United States and Canada. 

Wolverine populations number 2,089– 

3,567 in British Columbia and 1,500– 

2,000 in Alberta (COSEWIC 2003, p. 22), 

the two provinces immediately adjacent 

to the contiguous U.S. wolverine 

population. The difference in total 

population sizes is significant because 

critically small populations such as 

those in the contiguous United States 

face higher extinction risk than large 

ones such as the Canada-Alaska 

population. Therefore, the contiguous 

U.S. population is more vulnerable to 

extinction, and thus of poor 

conservation status, relative to the more 

secure Canada-Alaska population. 

Wolverines in Canada’s eastern 

provinces are listed under the Species at 

Risk Act of Canada. Wolverines in the 

eastern provinces appear to have been 

extirpated by the early 20th century 

(COSEWIC 2003, p. 20). There is a 

general lack of reliable historic 

information on wolverines in this area, 

and significant doubt exists about 

whether a population ever occurred 

there historically (COSEWIC 2003, p. 

20). For the purposes of this finding, we 

considered the Canadian wolverine 

population to include only wolverines 

from Ontario west to the Pacific coast 

and Alaska, and assumed that 

wolverines in eastern Canada were 

either extirpated or are at such low 

numbers as not to be part of a 

functioning population. It is our 

determination that the conservation 

status of the eastern population, if it 

does indeed exist, is not relevant to the 

discreteness analysis for this DPS for the 

following reasons: (1) If wolverines 

currently reside in the eastern Canadian 

Provinces, they are likely disjunct from 

wolverines in western Canada 

(COSEWIC 2003, Figure 3); and (2) there 

is significant doubt that wolverine 

populations existed in this part of 

Canada historically, so the current lack 

of evidence of a population may not 

represent a degradation of species status 

in this area (COSEWIC 2003, pp. 20–21). 

The second substantial difference in 

wolverine status between the 

contiguous United States and Canada is 

reflected in the size of the effective 

populations. Population ecologists use 

the concept of a population’s ‘‘effective’’ 

size as a measure of the proportion of 

the actual population that contributes to 

future generations (for a review of 

effective population size, see Schwartz 

et al. 1998, entire). In a population 

where all of the individuals contribute 

offspring equally, effective population 

size would equal true population size. 

For populations where contribution to 

the next generations is often unequal, 

effective population size will be smaller 

than the true or ‘‘census’’ population 

size. The smaller the effective 

population size, the more reproduction 

is dominated by a few individuals. 

Effective population size is important 

because it determines rates of loss of 

genetic variation, fixation of deleterious 

alleles and the rate of inbreeding. 

Populations with small effective 

population sizes show reductions in 

population growth rates and increases 

in extinction probabilities (Leberg 1990, 

p. 194; Jimenez et al. 1994, pp. 272–273; 

Newman and Pilson 1997, p. 360; 

Saccheri et al. 1998, p. 492; Reed and 

Bryant 2000, p. 11; Schwartz and Mills 

2005, p. 419; Hogg et al. 2006, p. 1495, 

1498; Allendorf and Luikart 2007, pp. 

338–342). Franklin (1980, as cited in 

Allendorf and Luikart 2007, p. 359) 

proposed an empirically based rule 

suggesting that for short-term (a few 

generations) maintenance of genetic 

diversity, effective population size 

should not be less than 50. For longterm (hundreds of generations) 

maintenance of genetic diversity, 

effective population size should not be 

less than 500 (for appropriate use of this 

rule and its limitations see Allendorf 

and Luikart 2007, pp. 359–360). Others 

suggest that even higher numbers are 

required to ensure that populations 

remain viable, suggesting that long-term 

connectivity to the reservoir of genetic 

resources in the Canadian population of 

wolverines will be required (Traill et al. 

2010, p. 32). 

Wolverine effective population size in 

the largest extant population in the 

contiguous United States is 

exceptionally low (Schwartz personal 

communication 2007, entire) and is 

below what is thought necessary for 

short-term maintenance of genetic 

diversity. Effective population size for 

wolverines in the Rocky Mountains 

averaged 39 (Schwartz personal 

communication 2007, entire) (this study 

excluded the small population from the 

Crazy and Belt Mountains (hereafter 

‘‘CrazyBelts’’) as they may be an isolated 

population, which could bias the 

estimate using the methods of Tallmon 

et al. (2007, entire)). Measures of the 

effective population sizes of the other 

populations in the contiguous United 

States have not been completed, but 

given their small census sizes, their 

effective sizes are expected to be smaller 

than for the northern Rocky Mountain 

population. Thus, wolverine effective 

population sizes are very low. For 

comparison, estimates of wolverine 

effective population size are bracketed 

by critically endangered species like the 

black-footed ferret (4.10) (Wisely et al. 


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2007, p. 3) and ocelots (2.9 to 13.9) 

(Janecka et al. 2007, p. 1), but 

substantially smaller than estimates for 

the Yellowstone Grizzly bear (greater 

than 100), which has reached the level 

of recovery under the Act (Miller and 

Waits 2003, p. 4338). Therefore, we 

conclude that effective population size 

estimates for wolverines do not suggest 

that populations are currently critically 

endangered, but they do suggest that 

populations are low enough that they 

could be vulnerable to loss of genetic 

diversity, and may require intervention 

in the future to remain viable. 

The concern with the low effective 

population size is highlighted in recent 

research that determined that, absent 

immigration, at least 400 breeding pairs 

would be necessary to sustain long-term 

genetic viability of the contiguous U.S. 

wolverine population (Cegelski et al. 

2006, p. 197). However, the entire 

population is likely 250–300 (Inman 

2010b, pers. comm.), with a substantial 

number of these being nonbreeding 

subadults. Furthermore, the U.S. 

population appears to be split into at 

least five smaller subpopulations 

(Northern Cascades, CrazyBelts, Idaho, 

Greater Yellowstone Ecosystem, and 

Northern Montana) that are semiisolated from each other, meaning that 

genetic exchange does not occur 

frequently enough to prevent genetic 

drift (changes in genetic composition 

due to random sampling in small 

populations) and loss of genetic 

diversity (Cegelski et al. 2006, p. 206) 

further reducing the effective 

population size. Based on available 

scientific and commercial information, 

it does not appear that any of the 

wolverine populations that historically 

existed in the contiguous United States 

would have had effective population 

sizes approaching 400 animals. 

Therefore, it is likely that connectivity 

to Canadian populations to the north 

would have been necessary to maintain 

genetic diversity in these populations 

prior to European settlement. 

The concern that low effective 

population size may result in negative 

effects is already being realized for the 

contiguous U.S. population of 

wolverine. Genetic drift has occurred in 

the remaining populations in the 

contiguous United States: wolverines 

here contain 3 of 13 haplotypes (sets of 

closely linked genetic markers that are 

inherited together) found in Canadian 

populations (Kyle and Strobeck 2001, p. 

343; Cegelski et al. 2003, pp. 2914– 

2915; Cegelski et al. 2006, p. 208; 

Schwartz et al. 2007, p. 2176; Schwartz 

et al. 2009, p. 3229). The haplotypes 

found in these populations are a subset 

of those in the larger Canadian 

population, indicating that genetic drift 

had caused a loss of genetic diversity. A 

single haplotype dominates the northern 

Rocky Mountain wolverine population, 

with 71 of 73 wolverine sampled 

expressing that haplotype (Schwartz et 

al. 2007, p. 2176). The reduced number 

of haplotypes indicates not only that 

genetic drift is occurring, but also that 

there is some level of genetic separation; 

if these populations were freely 

interbreeding, they would share more 

haplotypes. The reduction of haplotypes 

is likely a result of small population size 

and the fragmented nature of wolverine 

habitat in the United States and is 

consistent with an emerging pattern of 

reduced genetic variation at the 

southern edge of the range documented 

in a suite of boreal forest carnivores 

(Schwartz et al. 2007, p. 2177). Whether 

or not the wolverine population in the 

contiguous United States has suffered 

any deleterious effects due to this 

reduction in genetic diversity is 

unknown. However, based on principles 

of conservation genetics, we do expect 

that reduced genetic diversity would 

make this population more vulnerable 

to other threats due to reduced genetic 

resiliency and reduced ability to adapt 

to change (Allendorf and Luikart 2007, 

pp. 338–342). 

No effective population size estimate 

exists for populations in Canada or 

Alaska; however, because of the large 

and contiguous nature of the population 

and the relatively high genetic diversity 

in Canada and Alaska, there is a 

reasonable scientific basis to conclude 

that the effective population size is large 

enough that it is not a cause for 

conservation concern. None of the 

Canadian or Alaskan populations tested 

show signs of genetic drift or 

inbreeding. This information indicates 

that the population does not have a low 

effective population size. 

Reduced genetic diversity and low 

effective population sizes result in high 

extinction risk in animal populations 

(Frankham 1995, p. 795). The fragile 

nature of wolverine populations in the 

contiguous United States contrasts with 

Canada and Alaska where wolverines 

are relatively abundant and exist in 

habitats with a high level of 

connectivity (COSEWIC 2003, p.8; 

Slough 2007, p. 78). 

The third substantial difference in 

wolverine status between the 

contiguous United States and Canada is 

reflected by the amount and distribution 

of available habitat for the species. 

Habitat in the contiguous United States 

consists of small isolated ‘‘islands’’ of 

high-elevation alpine habitats separated 

from each other by low valleys of 

unsuitable habitats. Habitat islands are 

represented by areas containing spring 

snow (Copeland et al. 2010, Figure 2). 

Wolverine range in the contiguous 

United States is characterized by 

isolated mountain habitats dissected by 

lower-elevation valleys, while habitat in 

adjoining Canada comprises mostly 

large blocks of contiguous habitat 

(Copeland et al. 2010, Figure 2; 

Copeland 2010, pers. comm.). 

Wolverines occupy habitat at high 

elevations, generally above 2,100 m 

(6,888 ft), in the mountains of the 

contiguous United States. The 

intervening valleys in this area range 

from 975 m to 1,500 m (3,198 ft to 4,920 

ft), and are dominated by ecosystems 

that are unsuitable for long-term 

wolverine presence, but do serve as 

routes for wolverine movement between 

suitable habitat patches. Intermountain 

valleys are increasingly becoming the 

sites of human residential and 

commercial developments and 

transportation corridors. The large 

distances between suitable wolverine 

habitats results in wolverines existing 

on an archipelago of suitable habitats in 

a sea of unsuitable habitat. The low 

population density and genetic diversity 

of wolverines in this area requires that 

exchange of individual wolverines 

between islands of habitat occurs to 

avoid inbreeding or local extinction due 

to demographic stochasticity. 

Wolverine populations in the 

Canadian Rocky Mountains also exist on 

habitat islands, but the islands are much 

larger, so that exchange of individuals is 

less critical for demographic and genetic 

stability. Further north in Canada, 

where cold snowy conditions occur at 

lower elevations, wolverines inhabit 

lower elevations and valley bottom 

habitats (COSEWIC 2003, pp. 7–8). In 

the far north of Canada, wolverine 

habitat extends into low-elevation 

valleys and the vast expanses of lowelevation boreal forest and tundra. For 

these reasons, exchange of wolverines 

between habitat islands in the Canadian 

Rocky Mountains is both more likely to 

occur and less critical for the long-term 

maintenance of those populations. 

In the contiguous United States, 

wolverines must cross unsuitable 

habitats to achieve connectivity among 

subpopulations, which is required to 

avert further genetic drift and loss of 

genetic diversity (Kyle and Strobeck 

2002, p. 1148; Cegelski et al. 2006, pp. 

208–209; Schwartz et al. 2009, p. 3230). 

The highly fragmented nature of the 

habitat in the contiguous United States 

contributes to the low effective 

population size for wolverines in this 

area, making the continued persistence 

of the population precarious relative to 

the Canadian-Alaskan population. 


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Habitats in Canada and Alaska exist in 

larger contiguous blocks that have few 

or no impediments to demographic or 

genetic connectivity with peripheral 

smaller blocks (Copeland et al. 2010, 

Figure 2). The fragmented nature and 

distribution of wolverine habitat in the 

contiguous United States results in a 

population that is highly vulnerable to 

extirpation because of lack of 

connectivity between subpopulations, it 

also makes them more vulnerable to 

external threats such as those analyzed 

under the five threat factors below. 

Conservation status of wolverines in 

the contiguous United States differs 

significantly with that of the CanadaAlaska population. The Canada-Alaska 

population is large, well-connected, and 

exists in large blocks of contiguous 

habitat. In contrast, the population in 

the contiguous United States is small in 

total size and is fragmented on small 

patches of suitable habitat that are 

separated by large areas of unsuitable 

habitat. These differences result in a 

Canada-Alaska population that is robust 

and better able to respond to habitat 

changes, while the contiguous United 

States population is vulnerable to 

changes in habitat or management. We 

believe that the differences in 

conservation status between the 

contiguous United States and Canada 

are significant in light of section 

4(a)(1)(D) of the Act (inadequacy of 

existing regulatory mechanisms) 

because they reveal that the existing 

mechanisms in Canada are sufficient to 

maintain wolverine, while in the United 

States, the existing regulatory 

mechanisms are not sufficient to 

address the biological conservation 

concerns. 

Legal Status Conveyed by National, 

State, and Provincial Governments 

The United States currently confers 

no Federal status on the wolverine. Each 

State regulates the species relative to its 

existing populations. In Washington, the 

wolverine is listed as State Endangered 

(Washington Department of Fish and 

Wildlife 2010, entire). Idaho and 

Wyoming designate it as a protected 

nongame species (Idaho Fish and Game 

2010, p. 4; Wyoming Game and Fish 

2005, p. 4), and Montana regulates it as 

a furbearer (Montana Department of 

Fish, Wildlife, and Parks 2010, entire). 

Oregon, while currently not considered 

to have any individuals other than 

possible unsuccessful dispersers, has a 

closed season on trapping of wolverines. 

California and Colorado currently each 

have only one confirmed wolverine, and 

the States do not allow harvest. 

The Canadian Government has listed 

its Eastern population of wolverine as 

Endangered under the Species at Risk 

Act (SARA) in Quebec and Labrador, 

where it may be extirpated due to 

trapping and hunting and declining 

caribou herds (Government of Canada 

2010, entire). Because wolverines 

appear to have been extirpated from this 

area since the early part of the century 

and their historical status as a viable 

population is uncertain, we do not 

consider it to be in the current range, 

and thus consider the species’ status 

there not relevant to the question of 

whether significant differences in status 

exist between the two countries. The 

Western population of wolverines 

occurs in eight Provinces, two of which 

(British Columbia and Alberta) are 

contiguous to the wolverine range in the 

United States. This population in 

Canada has no status under SARA, but 

has a designation of Special Concern 

(Vulnerable) under the Committee on 

the Status of Endangered Wildlife in 

Canada (COSEWIC) (Government of 

Canada 2010, entire), a status that does 

not provide legal protections. British 

Columbia and Alberta have Provincial 

species conservation lists, which are 

priority-setting tools for establishing 

baseline ranks and conservation 

activities (Province of British Columbia 

2002, p. 1). Both Provinces include the 

wolverine on their provincial ‘‘blue list,’’ 

indicating that it may be at risk 

(Peterson 1997, p. 1), except on 

Vancouver Island where the wolverine 

is possibly extirpated and is ‘‘red listed’’ 

(threatened, endangered, or candidate; 

not harvested) (Lofroth and Ott 2007, p. 

2193; Province of British Columbia 

2002, p. 2). 

In our 2008 12-month finding, we 

determined that differences in 

management status conveyed by the 

States and Provinces that regulate 

wolverine management were not 

significantly different from each other, 

as States and Provinces both allowed 

regulated harvest and there were a 

variety of regulatory mechanisms in 

each. Regulatory status in the Canadian 

Provinces and U.S. States regulatory 

status remains unchanged, and we 

continue to find no significant 

difference between the legal status of 

wolverines between Canada and the 

United States. 

While similarities exist in the legal 

conservation statuses bestowed on the 

wolverine in the four U.S. States where 

it currently persists, and the two 

adjacent Canadian Provinces, the 

differences in biological conservation 

status are significant and affect the 

future of the species. In western Canada, 

the wolverine has no protection under 

SARA; in the United States the 

wolverine currently has no status under 

the Act. This allows piecemeal 

management by States and Provinces 

with little regard for regional 

management directed at the continued 

existence of the species in the 

contiguous United States. 

Because British Columbia and Alberta 

are contiguous to a larger, and more 

robust, portion of the wolverine’s range 

in northwestern Canada, documented 

declines in wolverine populations 

(likely due to harvest levels) in the 

southern portions of both Provinces 

have not raised the status of the species 

to a level of concern that would result 

in its consideration for status under 

SARA (Lofroth and Krebs 2007, pp. 

2164–2165; Lofroth and Ott 2007, p. 

2193; Peterson 1997, pp. 4–5). 

Differences in Control of Exploitation 

Significant differences exist in control 

of exploitation between the United 

States and Canadian wolverine 

populations. U.S. populations are 

largely not harvested, with the 

exception of a carefully controlled and 

very limited harvest in Montana; while 

in Canada, harvest is widespread 

throughout the provinces within the 

current range. British Columbia has a 3- 

to 4-month trapping season with no 

provincial quota, while adjacent 

Washington considers the species State 

Endangered and allows no trapping. 

Alberta allows a 3-month trapping 

season with quotas in 6 of its 8 fur 

management zones for an annual 

average harvest of 37 (zones 7 and 8 in 

Alberta are closed to trapping but are 

outside the species’ normal range and so 

the closure is of little conservation 

consequence (Province of Alberta 2007, 

entire)), while adjacent Montana allows 

up to a 2.5-month hunting and trapping 

season with a total quota of 5 

wolverines (maximum of 3 females). 

Although we do not have 

comprehensive numbers of the annual 

wolverine harvest in Canada, we have 

estimated a total annual harvest of 719 

animals (see Table 2) based upon the 

best information available to us. Based 

on available information, we presume 

this to be an underestimate, because it 

is based upon reported harvests, which, 

for Canadian territories, likely accounts 

for only one-fifth to one-third of the 

total harvest because of heavy 

unreported harvest and use by local 

communities (Melchoir et al. 1987 as 

cited in Banci 1994, p. 101). 


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TABLE 2—ESTIMATED ANNUAL WOLVERINE HARVEST IN CANADA

Province or territory Estimated annual 

harvest Source 

British Columbia ........................ 175 Lofroth and Ott, 2007, pp. 2196–2197. 

Alberta ....................................... 37 Province of Alberta 2006, p. 14. 

Saskatchewan ........................... 10 COSEWIC 2007, Table 1 

Manitoba ................................... 48 COSEWIC 2007, Table 1 

Ontario ...................................... 8 COSEWIC 2007, Table 1 

Yukon ........................................ 150 COSEWIC 2007, Table 1 

Northwest Territories ................ 209 COSEWIC 2007, Table 1 *

Nunavut ..................................... 82 COSEWIC 2007, Table 1 ∧ 

Total ................................... 719 

* Corrected to adjust for majority being unreported in pelt production statistics. 

∧ Corrected using Dumond and Krizan 2002 as cited in COSEWIC 2007 p. 17. 

Based upon these numbers, we 

conservatively estimate that harvest in 

Canada is a minimum of 4.7 percent of 

the population annually. This estimate 

is nearly three times the amount of 

harvest in the United States, which is 

approximately 5 animals of 300, or 1.6 

percent. We find that this nearly 300 

percent difference is significant, because 

the wolverine is sensitive to even small 

increases in mortality rates (Squires et 

al. 2007, p. 2218). Human-caused 

mortality of wolverines is likely 

additive to natural mortality due to the 

low reproductive rate and relatively 

long life expectancy of wolverines 

(Krebs et al. 2004, p. 499; Lofroth and 

Ott 2007, pp. 2197–2198; Squires et al. 

2007, pp. 2218–2219). 

These differences may be significant 

in light of section 4(a)(1)(D) of the Act, 

because they show that regulatory 

mechanisms are necessary in the United 

States and Canada to ensure that the 

contiguous U.S. population continues to 

receive migrants from the genetically 

richer Canadian population. However, 

the differences in control of exploitation 

favor the U.S. population, which is the 

population that is potentially at risk. In 

Canada, no such mechanisms are 

currently needed to protect the species. 

About 15,000 to 19,000 wolverines 

occur in western Canada where suitable 

habitat is plentiful (COSEWIC 2003, pp. 

14–21). Because of this abundance of 

habitat, conservative management and 

careful geographic control of harvest are 

not necessary to conserve wolverines in 

western Canada. This situation contrasts 

with the situation in the United States, 

where habitat is fragmented and 

wolverine populations are limited to 

high elevations over portions of four 

States (Washington, Idaho, Montana, 

and Wyoming). Because differences in 

control of exploitation exist, but control 

favors the at-risk population, we do not 

rely on control of exploitation to 

establish discreteness. 

Summary for Discreteness 

The international boundary between 

Canada and the United States currently 

leads to division of the control of 

exploitation and conservation status of 

the wolverine. This division is 

significant because it allows for 

potential extirpation of the species 

within the contiguous United States 

through loss of small populations and 

lack of demographic and genetic 

connectivity of the two populations. 

This difference in conservation status is 

likely to become more significant in 

light of threats discussed in the five 

factors analyzed below. Therefore, we 

find that the difference in the 

conservation statuses in Canada and the 

United States result in vulnerability to 

the significant threats (discussed below) 

in the U.S. wolverine population but not 

for the Canadian population. Existing 

regulatory mechanisms are inadequate 

to ensure the continued existence of 

wolverines in the contiguous United 

States in the face of these threats. 

Therefore, it is our determination that 

the difference in conservation status 

between the two populations is 

significant in light of section 4(a)(1)(D) 

of the Act, because existing regulatory 

mechanisms appear sufficient to 

maintain the robust conservation status 

of the Canada-Alaska population, while 

existing regulatory mechanisms in the 

contiguous United States are 

insufficient to protect the wolverine 

from threats due to its depleted 

conservation status. As a result, the 

contiguous United States population of 

the wolverine meets the discreteness 

criterion in our DPS Policy (61 FR 

4725). Consequently, we use the 

international border between the United 

States and Canada to define the 

northern boundary of the North 

American wolverine DPS. 

Analysis for Significance 

If we determine a population segment 

is discrete, its biological and ecological 

significance will then be considered in 

light of Congressional guidance that the 

authority to list DPS’s be used sparingly 

while encouraging the conservation of 

genetic diversity. In carrying out this 

examination, we consider available 

scientific evidence of the population’s 

importance to the taxon to which it 

belongs (i.e., the North American 

wolverine (Gulo gulo luscus). Our DPS 

policy states that this consideration may 

include, but is not limited to: (1) 

Persistence of the discrete population 

segment in an ecological setting unusual 

or unique for the taxon; (2) evidence 

that loss of the discrete population 

segment would result in a significant 

gap in the range of the taxon; (3) 

evidence that the discrete population 

segment represents the only surviving 

natural occurrence of a taxon that may 

be more abundant elsewhere as an 

introduced population outside its 

historic range; or (4) evidence that the 

discrete population segment differs 

markedly from other populations of the 

species in its genetic characteristics. 

Below we address Factors 1, 2, and 4. 

Factor 3 does not apply to the 

continental U.S. wolverine population 

because North American wolverines are 

distributed widely across Alaska and 

Canada. 

Significant Gap in the Range of the 

Taxon 

Loss of wolverines in the contiguous 

United States would represent a 

significant gap in the range of the taxon. 

Wolverines once lived throughout the 

North American Rocky Mountains from 

Alaska and Canada, south through 

Colorado and into New Mexico, and in 

the North Cascades of Washington and 

the Sierra Nevada Range of California— 

an extent covering approximately 38° of 

latitude. Wolverines were extirpated 


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from most of the southern portions of 

their historic range, including all of the 

Sierra Nevada in California and all of 

Colorado, and possibly even the North 

Cascades and northern Rocky 

Mountains in the early 20th century 

(Aubry et al. 2007, Table 1), a loss of 

approximately 15° of latitude. The 

wolverines that have moved to 

California and Colorado in the past 2 

years (Moriarty et al. 2009, Figure 1; 

Inman et al 2009, pp. 22–25) may 

represent the initial attempts to 

recolonize the southernmost extent of 

the species’ historic range and a 

continuation of a recolonization of the 

contiguous United States that began in 

the 1930s (Aubry et al. 2007, Table 1). 

Based on the current scientific 

information, we conclude that there is at 

least one wolverine each in the Sierra 

Nevada and southern Rocky Mountains. 

Both of these animals are males that 

dispersed from known populations 

rather than being from undiscovered 

remnant populations native to the 

regions in question, and there is no 

reason to believe that functional 

populations exist in these areas. Today, 

the contiguous United States represents 

the southernmost reach of the 

wolverine’s range. The loss of this 

population would be significant because 

it would substantially curtail the range 

of the wolverine by moving the southern 

range terminus approximately 15° of 

latitude to the north (or approximately 

40 percent of the latitudinal extent of 

wolverine range) and eliminate 

wolverines from the fauna of the 

contiguous United States. Therefore, the 

loss of this population would result in 

a significant gap in the range of the 

taxon. The estimated area that would be 

lost from wolverine range in North 

America if the contiguous U.S. 

population was extirpated is 205,942 

km2 (79,515 mi2) based on the habitat 

model developed by Copeland et al. 

(2010, entire; Copeland 2010, pers. 

comm.). 

Given the wolverine’s historic 

occupancy of the contiguous United 

States and the portion of the historic 

range they represent, maintenance and 

recovery of wolverines in their current 

range would provide some security for 

the rest of the taxon if conditions in 

Canada and Alaska deteriorated to the 

point that wolverines become 

endangered there. Populations on the 

periphery of species’ ranges tend to be 

given lower conservation priority 

because they are thought to exist in lowquality habitats, and are also thought to 

be the populations that are least likely 

to survive a reduction in range (Wolf et 

al. 1996, p. 1147). However, this 

tendency presumes that the ultimate 

cause of the species’ extinction will be 

one that operates by eroding away the 

species’ range beginning at the 

periphery and progressing to the center. 

This presumption is based on 

biogeographical information that habitat 

and population densities of species are 

highest near the center of the species’ 

range, and decline near the edge (Brown 

and Lomolino 1998, Figure 4.16). Data 

from real range collapses of species from 

around the world illustrate that species’ 

ranges tend to collapse to peripheral 

areas rather than to the center of their 

historic ranges (Lomolino and Channell 

1995, p. 342; Channell and Lomomolino 

2000, pp. 84–86). Of 96 species whose 

last remnant populations were found 

either in the core or periphery of their 

historic range (rather than some in both 

core and periphery), 91 (95 percent) of 

the species were found to exist only in 

the periphery, and 5 (5 percent) existed 

solely in the center (Channell and 

Lomolino 2000, p. 85). Available 

scientific data support the importance of 

peripheral populations for conservation 

(Fraser 1999, entire; Lesica and 

Allendorf 1995, entire). 

Based upon the 15 degree latitude gap 

that would result in the range of the 

wolverine if the U.S. population was 

lost, we determine that the loss of the 

contiguous U.S. wolverine population 

would result in a significant gap in the 

range of the taxon. Thus, the DPS meets 

the definition of significant in our DPS 

policy. 

Unusual or Unique Ecological Setting 

Wolverines in the contiguous United 

States exist in an ecosystem that 

requires extensive movements between 

habitats to maintain demographic 

viability and genetic diversity. Within 

the range of North American 

wolverines, the northern Rocky 

Mountains and North Cascades have the 

highest diversity of large predators and 

native ungulate prey species, which 

results in complex ecological interaction 

among ungulate prey, predators, 

scavenger groups, and vegetation (Smith 

et al. 2003, pp. 330–339). In the 

proposed DPS area, wolverines share 

habitats with gray wolves (Canis lupus), 

black bears (Ursus americanus), grizzly 

bears (Ursus arctos horribilis), puma 

(Felis concolor), lynx (Lynx canadensis), 

coyotes (Canis latrans), badgers 

(Taxidea taxus), bobcats (Felis rufus), 

fishers (Martes pennanti), and martens 

(Martes americana). The unique and 

diverse assemblage of native prey, and 

sources of carrion, for these carnivores 

include elk (Cervus elaphus), mule deer 

(Odocoileus hemionus), white-tailed 

deer (Odocoileus virginianus), moose 

(Alces alces), woodland caribou 

(Rangifer caribou), bighorn sheep (Ovis 

canadensis), mountain goats (Oreamnos 

americanus), pronghorn (Antilocapra 

americana), bison (Bison bison) (only in 

the Greater Yellowstone Area), and 

beaver (Castor canadensis). 

Despite the fragmented nature of the 

habitat and the high diversity of prey, 

wolverines in the contiguous United 

States appear to use habitat attributes 

that are similar to wolverine 

populations range-wide (Copeland et al. 

2010, entire), and do not appear to exist 

in an unusual or unique ecological 

setting. Thus, we did not rely on this 

factor when determining that the 

wolverine in the United States is 

significant to the taxon as a whole. 

Marked Genetic Differences 

Several genetics studies have 

confirmed genetic differentiation 

between wolverines in the contiguous 

United States and those in Canada and 

Alaska (Cegelski et al. 2006, pp. 203– 

205; Kyle and Strobeck 2002, p. 342; 

Schwartz et al. 2007, p. 2175). The U.S. 

Rocky Mountain populations group 

together in mitochondrial DNA 

(mtDNA) analyses (Schwartz et al. 2007, 

p. 2176). The primary genetic difference 

is a reduction of diversity in the United 

States as compared with Canada so that 

the contiguous U.S. populations contain 

a subset of the genetics of the CanadaAlaska population (Cegelski et al. 2006, 

p. 200; Schwartz et al. 2007, p. 2172). 

The contiguous U.S. populations 

contain 3 mtDNA haplotypes and 

Canada-Alaska samples also contain 

those three haplotypes plus ten more. 

Idaho has substantially lower 

heterozygosity (a measure of the genetic 

variation in a population) (42 percent) 

than the nearest Canadian population 

(61 percent) sampled only 700 km (435 

mi) away (Kyle and Strobeck, 2001, p. 

341, 345). Genetic structure in the 

contiguous United States indicates that 

population fragmentation caused by 

either natural or anthropogenic factors, 

has reduced gene flow between 

populations, and that genetic drift has 

occurred and may still be occurring 

(Kyle and Strobeck 2001, p. 343; 

Cegelski et al. 2003, pp. 2914–2915; 

Cegelski et al. 2006, p. 208). This 

reduced genetic diversity and gene flow 

coincides with the international border 

and indicates that individuals are not 

passing freely between Canadian and 

U.S. populations (Schwartz et al. 2009, 

pp. 3229–3230). Four wolverine 

subpopulations have been identified 

within Montana based on genetic data 

(Cegelski et al. 2003, p. 2913; Guillot et 

al. 2005, p. 1274). Subsequent work 

suggests that Montana may contain a 


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single population that is genetically 

structured by both distance and 

ecological factors meaning that 

wolverines across their range in 

Montana occasionally exchange 

individuals but do not freely interbreed 

because of the great distances and 

frequent unsuitable habitat that 

separates populations (Schwartz et al. 

2009, p. 3227). 

The levels of gene flow in the 

contiguous United States are low 

compared to wolverines in Alaska and 

Northern Canada (Kyle and Strobeck 

2001; 2002, pp. 343–345), indicating 

that habitat in the contiguous United 

States is much more fragmented than 

habitats further north in Canada and 

Alaska (Schwartz et al. 2009, p. 3227). 

A distinct break was identified between 

the U.S. population and the Canadian 

populations (Cegelski et al. 2006, p. 203; 

Schwartz et al. 2009, pp. 3229–3230). 

Similarly, Schwartz et al. (2007, p. 

2176) found that wolverines in Idaho, 

Montana, and Wyoming have few 

haplotypes (2 in the main Rocky 

Mountain group, plus 1 identified by 

Cegelski et al. 2006 in north-central 

Montana) compared to 13 distinct 

haplotypes in Canada, despite greater 

numbers of samples collected in the 

contiguous United States. Of these two 

haplotypes found by Schwartz, one is 

predominant, with 71 of 73 samples 

containing this haplotype (Schwartz et 

al. 2007, p. 2176). 

The genetic differences between the 

U.S. and Canadian wolverine 

populations identified above are the 

result of loss of genetic diversity, either 

through genetic drift or founder effects. 

The differences consist of lower genetic 

diversity in the United States, a 

difference that is of conservation 

concern because it reflects loss of 

genetic diversity through inbreeding. 

This is not the kind of genetic difference 

that would lead us to conclude that a 

population is significant under our DPS 

policy. That policy is designed to ensure 

the protection of rare or unique 

biological diversity rather than mere 

differences in gene frequencies. 

Therefore, we do not rely on marked 

genetic differences in our determination 

of significance for this DPS. 

Summary for Significance 

We conclude that the wolverine 

population in the contiguous United 

States is significant because its loss 

would result in a significant gap in the 

range of the taxon. 

Summary of the Distinct Population 

Segment Analysis 

We conclude that the wolverine 

population in the contiguous United 

States is both discrete and significant 

under our DPS policy. Conservation 

status of wolverines in the contiguous 

United States is less secure than 

wolverines in adjacent Canada due to 

fragmented habitat, small population 

size, reduced genetic diversity, and their 

vulnerability to threats analyzed in this 

finding. Loss of the contiguous U.S. 

wolverines would result in a significant 

gap in the range of the taxon. Therefore, 

we determine that the wolverine in the 

48 States, as currently described, meets 

both the discreteness and significance 

criteria of our DPS policy, and is a 

listable entity under the Act. We now 

consider the conservation status of this 

DPS. 

Summary of Information Pertaining to 

the Five Factors 

Section 4 of the Act (16 U.S.C. 1533) 

and implementing regulations (50 CFR 

part 424) set forth procedures for adding 

species to the Federal Lists of 

Endangered and Threatened Wildlife 

and Plants. Under section 4(a)(1) of the 

Act, a species may be determined to be 

endangered or threatened based on any 

of the following five factors: (A) The 

present or threatened destruction, 

modification, or curtailment of its 

habitat or range; (B) overutilization for 

commercial, recreational, scientific, or 

educational purposes; (C) disease or 

predation; (D) the inadequacy of 

existing regulatory mechanisms; or (E) 

other natural or manmade factors 

affecting its continued existence. In 

making this finding, information 

pertaining to the U.S. DPS of the 

wolverine in relation to the five factors 

provided in section 4(a)(1) of the Act is 

discussed below. 

We are required by the Act to assess 

threats information that may occur 

within the foreseeable future. We define 

foreseeable future as a timeframe in 

which impacts can be reasonably 

expected to occur. As discussed below, 

we have identified one primary threat to 

the wolverine DPS: climate change. 

Other threats are secondary and only 

rise to the level of threats to the DPS as 

they may work in concert with climate 

changes to affect the conservation status 

of the species. For this reason we use a 

foreseeable future identified for climate 

change (out to 2099) for all of the threat 

factors. For most threat factors, future 

projections are not available and it is 

assumed that current trends will 

continue unless information exists to 

the contrary. 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Under Factor A we will discuss a 

variety of impacts to wolverine habitat 

including: (1) Climate change, (2) 

human use and disturbance, (3) 

dispersed recreational activities, (4) 

infrastructure development, (5) 

transportation corridors, and (6) land 

management. Many of these impact 

categories overlap or act in concert with 

each other to affect wolverine habitat. 

Climate change is discussed under 

Factor A because although climate 

change may affect wolverines directly 

by creating physiological stress, the 

primary impact of climate change on 

wolverines is expected to be through 

changes to the availability and 

distribution of wolverine habitat. 

Two efforts to map wolverine habitat 

in the contiguous United States have 

been completed, although only one has 

been peer-reviewed (Brock et al. 2007, 

entire; Copeland et al. 2010, entire). As 

the single peer reviewed source, we rely 

on Copeland et al. (2010, entire) and 

supplemental information about that 

publication supplied in Copeland (pers. 

comm. 2010, p. 1) unless specified 

otherwise. We also report some statistics 

from the Brock et al. (2007) analysis 

because the authors report habitat 

broken down by land ownership 

whereas Copeland et al. (2010) do not. 

Both the Copeland et al. (2010) and 

Brock et al. (2007) analyses largely agree 

on the location of wolverine habitat 

within their geographic area of overlap; 

however, Brock et al. (2007) tends to be 

more inclusive and hence habitat area 

estimates for their model tend to be 

somewhat larger than for Copeland et al. 

(2010). Within the three States that 

currently harbor wolverines in the 

northern Rocky Mountains (Montana, 

Idaho, and Wyoming), an estimated 

104,363 km2 (40,295 mi2) of wolverine 

habitat exists (Copeland 2010, pers. 

comm.). Based on the habitat model 

developed by Brock et al. (2007), 95 

percent (120,000 km2; 46,332 mi2) is in 

Federal ownership with the largest 

portion of that (108,969 km2; 42,073 

mi2) managed by the U.S. Forest Service 

(Forest Service) (Inman 2007b, pers. 

comm.). 

Reduction in Habitat Due to Climate 

Change 

Department of the Interior Secretarial 

Order Number 3289, issued September 

14, 2009 (Department of the Interior 

(DOI) 2009), provides guidance that DOI 

bureaus and offices shall ‘‘* * * 

[c]onsider and analyze potential climate 

change impacts when undertaking longVerDate Mar<15>2010 18:37 Dec 13, 2010 Jkt 223001 PO 00000 Frm 00014 Fmt 4701 Sfmt 4702 E:\FR\FM\14DEP2.SGM 14DEP2

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range planning exercises, setting 

priorities for scientific research and 

investigations, developing multi-year 

management plans, and making major 

decisions regarding potential use of 

resources under the Department’s 

purview.’’ 

The Intergovernmental Panel on 

Climate Change (IPCC) was established 

in 1988 by the World Meteorological 

Organization and the United Nations 

Environment Program in response to 

growing concerns about climate change 

and, in particular, the effects of global 

warming. Although the extent of 

warming likely to occur is not known 

with certainty at this time, the IPCC has 

concluded that warming of the climate 

is unequivocal, and that continued 

greenhouse gas emissions at or above 

current rates will cause further warming 

(IPCC 2007, p. 30). Climate-change 

scenarios estimate that the mean air 

temperature could increase by more 

than 3 degrees Celsius (5.4 degrees 

Fahrenheit) by 2100 (IPCC 2007, p. 46). 

The IPCC also projects that there will 

very likely be regional increases in the 

frequency of hot extremes, heat waves, 

and heavy precipitation (IPCC 2007, p. 

46), as well as increases in atmospheric 

carbon dioxide (IPCC 2007, p. 36). 

We recognize that there are scientific 

uncertainties on many aspects of 

climate change, including the role of 

natural variability in climate. In our 

analysis, we rely both on synthesis 

documents (e.g., IPCC 2007; Karl et al. 

2009) that present the consensus view of 

a very large number of experts on 

climate change from around the world, 

and on three analyses that relate the 

effects of climate changes directly to 

wolverines (Gonzalez et al. 2008, entire; 

Brodie and Post 2009, entire; McKelvey 

et al. 2010b, entire). McKelvey et al. 

(2010b) is the most sophisticated 

analysis so far available of climate 

change effects to wolverines. This report 

is based on data from global climate 

models including both temperature and 

precipitation downscaled to reflect the 

regional climate patterns and 

topography found within the range of 

wolverines in the contiguous United 

States. For this reason we believe the 

McKelvey et al. (2010) report represents 

the best scientific information available 

regarding the impacts of climate change 

to wolverine habitat for this 12-month 

finding. 

Brodie and Post (2009) uses 

correlation to infer historical impacts of 

climate changes on Canadian wolverine 

populations based on harvest returns, 

but does not provide predictions of the 

future effects of climate changes on 

wolverines or wolverine habitat. Their 

report is suggestive of likely negative 

impacts to wolverine populations from 

continued warming; however, they do 

not provide estimates of the scale or 

spatial extent of future impacts. The 

Brodie and Post (2009) paper has also 

received several published criticisms of 

its methods (McKelvey et al. 2010a, 

entire; Devink et al. 2010, entire). The 

authors responded to these criticisms, 

although the controversy remains 

(Brodie and Post 2010b, entire). The 

report by Gonzalez et al. (2008) was the 

first available wolverine climate change 

analysis; however, the methods used in 

the report took into account only 

changes in temperature and not 

precipitation. 

Snowpack changes (and concomitant 

changes to wolverine habitat suitability) 

result from both changes in temperature 

(negative relationship) and changes in 

snowfall (positive relationship). Because 

many climate models predict higher 

precipitation levels associated with 

climate warming, the interaction 

between these two variables can be 

quite complex. Consequently, 

predictions about snow coverage that 

rely only on temperature projections are 

less reliable than those that rely on both 

temperature and precipitation. 

McKelvey et al. (2010b, entire) report 

projections for wolverine habitat and 

dispersal routes through the time 

interval from 2070 to 2099. Therefore, 

we use 2099 as the outer limit of the 

foreseeable future for climate change in 

this finding. 

Climate Effects to Wolverines 

Across their worldwide distribution, 

wolverines are dependent on persistent 

spring snow cover for successful 

reproduction (Pulliainen 1968, pp. 338– 

341; Myrberget 1968, p. 115; Copeland 

1996, pp. 93–94; Magoun and Copeland 

1998, pp. 1315–1319; Aubry et al. 2007, 

p. 2153; Inman et al. 2007c, pp. 71–72; 

Copeland et al. 2010, entire). No records 

exist of wolverines denning anywhere 

but in snow, despite the wide 

availability of snow-free denning 

opportunities within the species’ 

geographic range. The snow tunnel and 

complex structure associated with dens 

is likely required to protect young from 

interspecific and intraspecific predation 

(Persson et al. 2003, pp. 25–26; Magoun 

and Copeland 1998, p. 1318). A layer of 

deep snow may also add crucial 

insulation from cold temperatures and 

wind prevalent in denning habitat 

(Pulliainen 1968, p. 342; Bja ̈rvall et al. 

1978, p. 24–25; Copeland 1996, p. 100; 

Magoun and Copeland 1998, p. 1318). 

Female wolverines have been 

observed to abandon reproductive dens 

when temperatures warm and snow 

conditions become wet (Magoun and 

Copeland 1998, p. 1316), indicating that 

the condition of the snow is also 

important to successful reproduction, 

and that the onset of spring snowmelt 

forces female wolverines to move kits 

into alternate denning sites with better 

snow conditions, if they are available. 

Female wolverines establish 

reproductive dens at elevations higher 

than those used by non-reproductive 

wolverines (Copeland 1996, p. 94; 

Magoun and Copeland 1998, pp. 1315– 

1316; Inman et al. 2007c, p. 71), 

suggesting that females find the 

conditions necessary for successful 

denning in the upper portion of their 

home range where snow is most 

persistent and occurs in the heaviest 

accumulations. 

In the contiguous United States, 

wolverine year-round habitat is found at 

high elevations in conifer forests near 

treeline and in rocky alpine habitats 

such as cirque basins and avalanche 

chutes that have food sources such as 

marmots, voles, and carrion (Hornocker 

and Hash 1981, p. 1296; Copeland 1996, 

p. 124; Magoun and Copeland 1998, p. 

1318; Copeland et al. 2007, p. 2211; 

Inman et al. 2007a, p. 11). In fact, the 

areas defined by persistent spring snow 

cover that wolverines use for denning 

also correspond closely to wolverine 

habitat use in the nonreproductive 

season; essentially, wolverines use the 

coldest available landscapes within 

their geographic range in the contiguous 

United States (Copeland et al. 2010, 

Figure 6), likely due to a physiological 

need for cooler temperatures during the 

warm season. 

Mean seasonal elevations used by 

wolverines in the northern Rocky 

Mountains and North Cascades vary 

between 1,400 and 2,600 m (4,592 and 

8,528 ft) depending on location, but are 

always relatively high on mountain 

slopes (Hornocker and Hash 1981, p. 

1291; Copeland et al. 2007, p. 2207, 

Aubry et al. 2007, p. 2153). Elevation 

ranges used by historical wolverine 

populations in the Sierra Nevada and 

southern Rocky Mountains are 

unknown, but presumably wolverines 

used higher elevations, on average, than 

more northerly populations to 

compensate for the higher temperatures 

found at lower latitudes. In the 

contiguous United States, valley bottom 

habitat appears to be used only for 

dispersal movements and not for 

foraging or reproduction (Inman et al. 

2009, pp. 22–28). Wolverine 

reproductive dens have been located in 

alpine, subalpine, taiga, or tundra 

habitat (Myrberget 1968, p. 115; 

Pulliainen 1968, pp. 338–341; Bja ̈rvall 

1982, p. 318; Lee and Niptanatiak 1996, 

p. 349; Landa et al. 1998, pp. 451–452; 


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Magoun and Copeland 1998, pp. 1317– 

1318). Wolverines rarely, or never, den 

in lower elevation forested habitats, 

although they may occupy these 

habitats seasonally (Magoun and 

Copeland 1998, p. 1317). 

Due to dependence of wolverines on 

deep snow that persists into late spring 

both for successful reproduction and for 

year-round habitat, and their restricted 

distribution in areas that maintain 

significant snow late into the spring 

season, we conclude that deep snow 

maintained through the denning period 

is an essential feature of wolverine 

habitat. Reduction of this habitat feature 

would reduce wolverine habitat 

proportionally. 

Based on the information described 

above, we analyzed the effects of 

climate change on wolverines through 

three primary mechanisms: (1) Reduced 

snowpack and earlier spring runoff, 

which would reduce suitable habitat for 

wolverine denning; (2) increase in 

summer temperatures beyond the 

physiological tolerance of wolverines; 

and (3) ecosystem changes due to 

increased temperatures, which would 

move lower elevation ecosystems to 

higher elevations, eliminating highelevation ecosystems on which 

wolverines depend and increasing 

competitive interactions with species 

that currently inhabit lower elevations. 

These mechanisms would tend to push 

the narrow elevational band that 

wolverines use up in elevation and, due 

to the conical structure of mountains, 

upward shifts would result in reduced 

overall suitable habitat for wolverines. 

Reduced Snow Pack 

Warmer winter temperatures are 

reducing snow pack in western North 

American mountains through a higher 

proportion of precipitation falling as 

rain and higher rates of snowmelt 

during winter (Hamlet and Lettenmaier 

1999, p. 1609; Brown 2000, p. 2347; 

Mote 2003, p. 3–1; Christensen et al. 

2004, p. 347; Knowles et al. 2006, pp. 

4548–4549). This trend is expected to 

continue with future warming (Hamlet 

and Lettenmaier 1999, p. 1611; 

Christensen et al. 2004, p. 347; Mote et 

al. 2005, p. 48). Shifts in the initiation 

of spring runoff toward earlier dates are 

also well documented (Hamlet and 

Lettenmaier 1999, p. 1609; Brown 2000, 

p. 2347; Cayan et al. 2001, pp. 409–410; 

Christensen et al. 2004, p. 347; Mote et 

al. 2005, p. 41; Knowles et al. 2006, p. 

4554). Earlier spring runoff leads to lack 

of snow or degraded snow conditions 

during April and May, the critical time 

period for wolverine reproductive 

denning. In addition, a feedback effect 

hastens the loss of snow cover due to 

the reflective nature of snow and the 

relative heat-absorbing properties of 

non-snow-covered ground. This effect 

leads to the highest magnitude of 

warming occurring at the interface of 

snow-covered and exposed areas, 

increasing the rate at which melting 

occurs in spring (Groisman et al. 1994a, 

pp. 1637–1648; Groisman et al. 1994b, 

pp. 198–200). Due to the importance of 

deep snow cover in spring for wolverine 

reproduction, currently suitable habitat 

that lost this feature would be rendered 

unsuitable for wolverines. 

Ecosystem Changes Associated With 

Climate Change 

Changes in temperature and rainfall 

patterns are expected to shift the 

distribution of ecosystems northward 

(IPCC 2007c, p. 230) and up mountain 

slopes (McDonald and Brown 1992, pp. 

411–412; Danby and Hik 2007, pp. 358– 

359, IPCC 2007c, p. 232). As climate 

changes over a landscape, the 

ecosystems that support wolverines are 

likely to move, tracking the change of 

temperature, but with a time lag 

depending on the ability of individual 

plant species to migrate (McDonald and 

Brown 1992, pp. 413–414; Hall and 

Fagre 2003, p. 138; Peterson 2003, p. 

652). Wolverines in the contiguous 

United States, due to their reliance on 

mountainous habitat, will most likely 

adjust to climate changes by using 

higher elevations on mountain slopes, 

not by shifting their latitudinal 

distribution. Along a latitudinal 

gradient through the historic 

distribution of wolverines, records 

tended to be found at higher elevations 

in southern latitudes (Aubry et al. 2007, 

p. 2153), which suggests that wolverines 

were compensating for increased 

temperature at low latitudes by selecting 

higher elevations. Therefore, the 

regional availability of suitable habitat 

is not likely to change significantly (i.e., 

at least some wolverine habitat will 

continue to be available in all regions 

where wolverines currently occur), but 

within regional landscapes, smaller 

areas will be suitable for wolverines. 

Mountain ranges with maximum 

elevations within the elevation band 

that wolverines currently use, such as 

much of the wolverine habitat in central 

Idaho, may become entirely unsuitable 

for wolverines with the projected level 

of warming reported in McKelvey et al. 

(2010b, Figure 3). 

Timing of Climate Effects 

Unlike snow conditions, which 

respond directly to temperature change 

without a time lag, ecosystem responses 

to temperature change lag depending on 

constituent species’ individual 

migratory abilities. Wolverines are 

described as a ‘‘treeline’’ species because 

they are most often found in an 

elevation band that is approximately 

centered on the alpine treeline at any 

given locality within their range. Alpine 

treelines are maintained by a complex 

set of climactic and biotic factors, of 

which temperature is significantly 

important (Cogbill and White 1991, p. 

169; Ha ̈ttenschwiler and Ko ̈rner 1995, p. 

367; Jobba ́gy and Jackson 2000, p. 259; 

Pellat et al. 2000, pp. 80–81). However, 

the conditions that favor tree 

establishment and lead to elevational 

advance in the treeline may exist only 

sporadically, increasing time lags 

associated with treeline response to 

warming (Hessl and Baker 1997, p. 181; 

Klasner and Fagre 2002, p. 54). Within 

wolverine habitats, treelines have 

advanced up mountain slopes since 

1850, due to climate warming, and this 

trend is expected to continue into the 

future (Hessl and Baker 1997, p. 176; 

Hall and Fagre 2003, p. 138). We expect 

that species reliant on resources 

associated with this biome will need to 

shift accordingly. Given the irregular 

nature of treeline response to warming, 

treeline migration is likely to lag 

significantly behind the climate 

warming that causes it. 

Magnitude of Climate Effects on 

Wolverine 

Several studies relating the effects of 

climate changes on wolverines in the 

past, present, and future are now 

available (Brock and Inman 2007, entire; 

Gonzales et al. 2008, pp. 1–5; Brodie 

and Post 2010, entire; McKelvey et al. 

2010b, entire). The Gonzalez et al. 

report and the report by Brock and 

Inman (2007) were both preliminary 

attempts to analyze climate change 

impacts to wolverines, but are not 

currently considered the best available 

science because they did not consider 

the effects of both changes in 

temperature and precipitation that may 

affect the distribution of persistent 

spring snow cover (McKelvey 2010, 

entire). Both Brock and Inman (2007) 

and Gonzalez et al. (2008) have been 

superseded by a more sophisticated 

analysis provided by McKelvey et al. 

(2010b). This analysis includes climate 

projections at a local scale for wolverine 

habitats and analyzes the effects of both 

temperature changes and changes to 

precipitation patterns. Lack of 

accounting for changes in precipitation 

was a weakness cited by the authors of 

both Brock and Inman (2007) and 

Gonzalez et al. (2008). 

Brodie and Post (2010, entire) 

correlate the decline in wolverine 

populations in Canada over the past 


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century with declining snowpack due to 

climate change over the same period. 

However, correlation does not infer 

causation; other factors could have 

caused the decline. The analysis used 

harvest data to infer population trends 

as well as its reliance on correlation to 

infer causation (McKelvey et al. 2010a, 

entire); in this case, historic climate 

changes are inferred to have caused the 

declines in harvest returns, which are 

thought by the authors to reflect actual 

population declines. Due to the abovestated concerns, we view the analysis of 

Brodie and Post (2010, entire) with 

caution, although we do agree that the 

posited mechanism, of loss of snowpack 

affecting wolverine populations and 

distribution, likely has merit. 

McKelvey et al. (2010, entire) used 

downscaled global climate models to 

project the impacts of changes in 

temperature and precipitation to 

wolverine habitat as modeled by 

Copeland et al. (2010, entire). The 

authors also present an alternative 

method for evaluating climate impacts 

on wolverine habitat, by merely 

projecting onset of spring snowmelt to 

occur 2 weeks earlier than it currently 

does, essentially asking the question: 

What would happen if spring snowmelt 

occurred 2 weeks earlier than it occurs 

now? Based on this information, 

wolverine habitat in the contiguous 

United States, which supports 

approximately 250 to 300 wolverines, is 

shrinking and is likely to continue to 

shrink with increased climate warming 

(McKelvey et al. 2010b, Figures 1, 3). 

Habitat losses are likely to occur 

throughout the range of the DPS and are 

projected to be most severe in central 

Idaho (McKelvey et al. 2010b, Figures 1, 

3). However, large areas of snow cover 

are likely to remain in British Columbia, 

North Cascades, Greater Yellowstone 

Area (GYA), and the Glacier Park-Bob 

Marshall Wilderness of Montana 

(McKelvey et al. 2010b, p. 14, Figure 2). 

The southern Rocky Mountains of 

Colorado retained significant highelevation snow in some models but not 

others, and so may be another area that 

could support wolverine populations in 

the face of climate changes (McKelvey et 

al. 2010b, p. 19). The mountainous areas 

of Idaho that currently support 

wolverines are likely to lose 

proportionally more snow-covered area 

than other areas within the contiguous 

United States, making this area of 

wolverine habitat relatively more 

sensitive to climate warming (McKelvey 

et al. 2010b, p. 14). 

Overall, wolverine habitat in the 

contiguous United States is expected to 

get smaller and more highly fragmented 

as individual habitat islands become 

smaller and the intervening areas 

between wolverine habitat become 

larger (McKelvey et al. 2010b, Figures 1, 

3). Composite projections for the time 

interval centered on 2045 predict that 

23 percent of current wolverine habitat 

in the contiguous United States will be 

lost due to climate warming (McKelvey 

et al. 2010b, p. 14). That loss expands 

to 63 percent of wolverine habitat by the 

time interval between 2070 and 2099. 

Given the spatial needs of animals with 

the home range size of wolverines and 

the limited availability of suitable 

wolverine habitat in the contiguous 

United States, this projected gross loss 

of habitat area should result in a loss of 

wolverine numbers that is greater than 

the overall loss of habitat area. As 

habitat patches become smaller and 

more isolated, they are likely to lose the 

ability to support wolverines as some 

home ranges become so reduced that 

they cannot support individual animals, 

and others become so fragmented or 

isolated that they no longer continue to 

function. 

In addition to the effects of gross 

habitat loss, we expect wolverine 

populations to be negatively affected by 

changes in the spatial distribution of 

habitat patches as remaining habitat 

islands become progressively more 

isolated from each other as a result of 

climate changes (McKelvey et al. 2010b, 

Figure 8). Currently, wolverine habitat 

in the contiguous United States can be 

described as a series of habitat islands. 

Some of these islands are large and 

clumped closely together, such as in the 

North Cascades, Glacier Park-Bob 

Marshall Wilderness complex in 

Montana, and the GYA. Other islands 

are smaller and more isolated such as 

the island mountain ranges of central 

and southwestern Montana. Inbreeding 

and consequent loss of genetic diversity 

has occurred in the past within these 

smaller islands of habitat (Cegelski et al. 

2006, p. 208), and genetic exchange 

between subpopulations is most 

difficult to achieve (Schwartz et al. 

2009, Figure 4). Climate change 

projections indicate that, as warming 

continues, large contiguous blocks will 

become reduced in size and isolated to 

the extent that their ability to support 

robust populations is reduced and their 

connectivity to other source populations 

resembles the current situation for our 

most isolated wolverine populations 

(McKelvey et al. 2010b, Figure 8). This 

habitat alteration would result in a high 

likelihood of loss of genetic diversity 

due to inbreeding within a few 

generations (Cegelski et al. 2006, p. 

209). Further isolation of wolverines on 

small habitat islands with reduced 

connectivity to other populations would 

also increase the likelihood of 

subpopulations loss due to demographic 

stochasticity, impairing the 

functionality of the wolverine 

metapopulation in the contiguous 

United States. 

We believe that McKelvey et al. 

(2010b, entire) represents the best 

available science for predicting the 

future impacts of climate change on 

wolverine habitat for four primary 

reasons. First, their habitat projections 

are based on Global Climate Models 

which are thought to be the most 

reliable predictors of future climate 

available (IPCC 2007a, p. 12). Second, 

they conducted downscaling analyses to 

infer geographic climate variation at a 

scale relevant to wolverine habitat. 

Third, they used a hydrologic model to 

predict snow coverage during the spring 

denning period (the strongest correlate 

with wolverine reproductive success). 

Fourth, they used the habitat model 

developed by Copeland et al. (2010, 

entire), to relate projected climate 

changes to wolverine habitat. This 

report has not been peer-reviewed or 

published at the time of this finding; 

however, based on our analysis of the 

methods and analysis used by the 

authors, we conclude it constitutes the 

best available information on the likely 

impact of climate change on wolverine 

distribution in the contiguous United 

States. Based on the analysis presented, 

we conclude that climate changes are 

likely to result in permanent loss of a 

significant portion of essential 

wolverine habitat within the foreseeable 

future. Additional impacts of climate 

change will be increased habitat 

fragmentation as habitat islands become 

smaller and intervening habitat 

disappears. Eventually, these processes 

are likely to lead to a breakdown of 

metapopulation dynamics as 

subpopulations are no longer able to 

rescue each other after local extinctions 

due to a lack of connectivity. It is also 

likely that loss of genetic diversity 

leading to lower fitness will occur as 

population isolation increases. 

Summary of Impacts of Climate 

Changes 

Wolverine habitat is projected to 

decrease in area and become more 

fragmented within the foreseeable future 

as a result of climate changes. These 

impacts are expected to have direct and 

indirect effects to wolverine populations 

in the contiguous United States 

including reducing the number of 

wolverines that can be supported by 

available habitat and reducing the 

ability of wolverines to travel between 

patches of suitable habitat. This 


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reduction in connectivity is likely to 

affect metapopulation dynamics making 

it more difficult for subpopulations to 

recolonize areas where wolverines have 

been extirpated and to bolster the 

genetics or demographics of adjacent 

subpopulations. Due to the extent and 

magnitude of climate change impacts to 

wolverines and their habitat, we 

conclude that climate change 

constitutes a threat to the contiguous 

U.S. DPS of wolverines in the 

foreseeable future. 

Habitat Impacts Due to Human Use and 

Disturbance 

Because wolverine habitat is generally 

inhospitable to human use and 

occupation and most of it is also 

Federally managed, wolverines are 

somewhat insulated from impacts of 

human disturbances from industry, 

agriculture, infrastructure development, 

or recreation. Human disturbance in the 

contiguous United States has likely 

resulted in the loss of some wolverine 

habitat, although this loss has not yet 

been quantified. Sources of human 

disturbance to wolverines include 

winter and summer recreation, housing 

and industrial development, road 

corridors, and extractive industry such 

as logging or mining. In the contiguous 

United States, these human activities 

and developments often occur within or 

immediately adjacent to wolverine 

home ranges, such as in alpine or boreal 

forest environments at high elevations 

on mountain slopes. They can also 

occur in a broader range of habitats that 

are occasionally used by wolverines 

during dispersal or exploratory 

movements—habitats that are not 

suitable for the establishment of home 

ranges and reproduction. 

Little is known about the behavioral 

responses of individual wolverines to 

human presence, or about the species’ 

ability to tolerate and adapt to repeated 

disturbance. Some postulate that 

disturbance may reduce the wolverine’s 

ability to complete essential life-history 

activities, such as foraging, breeding, 

maternal care, routine travel, and 

dispersal. It may decrease habitat value, 

cause animals to avoid disturbed areas, 

or act as a barrier to movement (Packila 

et al. 2007, pp. 105–110). How effects of 

disturbance extend from individuals to 

characteristics of populations, such as 

vital rates (e.g., reproduction, survival, 

emigration, and immigration) and gene 

flow, and ultimately to wolverine 

population or meta-population 

persistence, is unknown. 

Wolverine habitat is generally 

characterized by the absence of human 

presence and development (Hornocker 

and Hash 1981, p. 1299; Banci 1994, p. 

114; Landa et al. 1998, p. 448; Rowland 

et al. 2003, p. 101; Copeland 1996, pp. 

124–127; Krebs et al. 2007, pp. 2187– 

2190). This negative association is 

sometimes interpreted as active 

avoidance of human activity, but it may 

simply reflect the wolverine’s 

preference for cold, snowy, and highelevation habitat. In the contiguous 

United States, wolverine habitat is 

typically associated with high-elevation 

(e.g., 2,100 m to 2,600 m (6,888 ft to 

8,528 ft)) subalpine forests that 

comprise the Hudsonian Life Zone 

(weather similar to that found in 

northern Canada), environments not 

typically used by people for housing, 

industry, agriculture, or transportation. 

However, occupied wolverine habitat 

supports a variety of activities 

associated with extractive industry, 

such as logging and mining, as well as 

recreational activities in both summer 

and winter. 

At broad spatial scales, it is difficult 

to separate human disturbance from 

negative, although interdependent, 

effects of habitat loss and fragmentation, 

and historic overexploitation; factors 

that could contribute to current 

differences in distributions of 

wolverines and humans. 

Maternal females and their young 

often vacate dens if they feel threatened 

(Myrberget 1968, p. 115), which is a 

common predator avoidance strategy 

among carnivores. The security of the 

den and the surrounding foraging areas 

(i.e., protection from disturbance by 

humans and predation by other 

carnivores) is an important aspect of 

den site selection. Abandonment of 

natal and maternal dens may also be a 

preemptive strategy that females use in 

the absence of disturbance by humans 

or predators. Preemptive den 

abandonment might confer an advantage 

to females if prolonged use of the same 

den makes that den more evident to 

predators. 

The reasons for den abandonment are 

uncertain. Managing human activity in 

wolverine habitat to limit premature 

den abandonment and associated stress 

and energy expenditure of maternal 

females may be important for successful 

reproduction. Premature den 

abandonment may also increase 

incidental mortality of offspring. 

Ultimately, low reproductive success 

and high mortality may reduce 

population viability in areas with high 

incidence of disturbance (Banci 1994, 

pp. 110–111). The potentially negative 

effects of disturbance may be more 

important at the southern margin of the 

species’ North American range where 

wolverine productivity is particularly 

low (Inman et al. 2007c, p. 70). 

Wolverines typically occupy severe, 

unproductive environments that 

support low numbers of adult females 

with characteristically low birth rates 

(Persson et al. 2006, p. 77; Inman et al. 

2007a, p. 68). The life-history strategy of 

wolverines makes it unlikely that they 

could compensate for increased 

mortality due to disturbance (Krebs et 

al. 2007, p. 2190; Persson et al. 2006, 

pp. 77–78), and they may be more 

vulnerable to extirpation than species 

with high reproductive rates (Ruggiero 

et al. 2007, p. 2146). 

For the purposes of this finding, we 

divide human disturbance into four 

categories: (1) Dispersed recreational 

activities with primary impacts to 

wolverines through direct disturbance 

(e.g., snowmobiling and heli-skiing); (2) 

disturbance associated with permanent 

infrastructure such as residential and 

commercial developments, mines, and 

campgrounds; (3) disturbance and 

mortality associated with transportation 

corridors; and (4) disturbance associated 

with land management activities such as 

forestry, or fire/fuels reduction 

activities. Overlap between these 

categories is extensive, and it is often 

difficult to distinguish effects of 

infrastructure from the dispersed 

activities associated with that 

infrastructure. However, we believe that 

these categories account for most of the 

potential effects related to disturbance 

of wolverines. 

Dispersed Recreational Activities 

Dispersed recreational activities 

occurring in wolverine habitat include 

snowmobiling, heli-skiing, hiking, 

biking, off- and on-road motorized use, 

hunting, fishing, and other uses. Among 

the most often cited as potential threats 

to wolverines are snowmobiling and 

heli-skiing; however, other dispersed 

recreation activities may have similar 

effects. 

One study documented (in two 

reports) the extent that winter 

recreational activity spatially and 

temporally overlapped wolverine 

denning habitat in the contiguous 

United States (Heinemeyer and 

Copeland 1999, pp. 1–17; Heinemeyer et 

al. 2001, pp. 1–35). This study took 

place in the GYA in an area of high 

dispersed recreational use. The overlap 

of modeled wolverine denning habitat 

and dispersed recreational activities was 

extensive. Strong temporal overlap 

existed between snowmobile activity 

(February–April) and the wolverine 

denning period (February–May). During 

2000, six of nine survey units, ranging 

from 3,500 to 13,600 hectares (ha) (8,645 

to 33,592 acres (ac)) in size, showed 

evidence of recent snowmobile use. 


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Among the six survey units with 

activity, the highest use covered 20 

percent of the predicted denning 

habitat, and use ranged from 3 to 7 

percent over the other survey units. 

Snowmobile activity was typically 

intensive where detected. 

Three of nine survey units in this 

study showed evidence of skier activity 

(Heinemeyer and Copeland 1999, p. 10; 

Heinemeyer et al. 2001, p. 16). Among 

the three units with activity, skier use 

covered 3 to 19 percent of the survey 

unit. Skiers also intensively used the 

sites they visited. Combined skier and 

snowmobile use covered as much as 27 

percent of potential denning habitat in 

one unit, where no evidence of 

wolverine presence was detected. 

Although we do not have any 

information on the overlap of wolverine 

and winter recreation in the remaining 

part of the U.S. range, these areas likely 

do not get the high levels of recreational 

use seen in the portion of the GYA 

examined in this study. 

Although we can demonstrate that 

recreational use of wolverine habitat is 

heavy in some areas, we do not have 

any information on the effects of these 

activities on the species. No rigorous 

assessments of anthropogenic 

disturbance on wolverine den fidelity, 

food provisioning, or offspring survival 

have been conducted. Disturbance from 

foot and snowmobile traffic associated 

with historic wolverine control 

activities (Pulliainen 1968, p. 343), and 

field research activities, may cause 

maternal females to abandon natal dens 

and relocate kits to maternal dens 

(Myrberget 1968, p. 115; Magoun and 

Copeland 1998, p. 1316; Inman et al. 

2007c, p. 71). 

At both a site-specific and landscape 

scale, wolverine natal dens were located 

particularly distant from public (greater 

than 7.5 km (4.6 mi)) and private 

(greater than 3 km (1.9 mi)) roads (May 

2007, p. 14–31). Placement of dens away 

from public roads (and away from 

associated human-caused mortality) was 

also a positive influence on successful 

reproduction. It is not known if the 

detected effect is due to the influence of 

the roads themselves or if there are 

other habitat variables that cause the 

effect that are also correlated with a lack 

of roads. 

Disturbance at maternal dens may be 

more likely to cause displacement than 

disturbance at natal dens (Magoun and 

Copeland 1998, p. 1316), and maternal 

dens may be less secure from predators 

than natal dens (Myrberget 1968, p. 

115), presumably because maternal dens 

are shallower and smaller. After pursuit 

by Scandinavian hunters, females near 

parturition used birthing sites that were 

less secure than natal dens (Pulliainen 

1968, p. 343). Maternal females 

apparently carry or pull their offspring 

to new den sites, and may be 

constrained by the distance and 

difficulty of simultaneously moving 

several reluctant offspring (Myrberget 

1968, p. 115). 

Stress from human activities has not 

been shown to affect reproductive rates, 

or to render home range or larger areas 

of habitat unsuitable. However, the 

absence of human disturbance that is 

afforded by refugia may be important for 

wolverine reproduction (Banci 1994, p. 

122; Copeland 1996, p. 126). The extent 

that dispersed winter recreational 

activities affect selection of natal den 

sites by female wolverines is little 

studied. Rugged terrain and dense 

forests may naturally separate natal 

dens and wolverine foraging areas from 

centers of snowmobile or backcounty 

skier activity. Maternal females may 

specifically choose to locate dens far 

from winter recreation (Inman et al. 

2007c, p. 72; Heinemeyer and Copeland 

1999, p. 2–9). Six of seven natal dens 

documented in the Yellowstone 

Ecosystem occurred where snowmobiles 

were not permitted, such as in 

designated wilderness or national parks 

(Inman et al. 2007c); recreational 

snowmobile use outside of these areas 

was common. Wolverine den, foraging, 

and traveling areas have anecdotally 

been found to be spatially separated 

from snowmobile activity (Heinemeyer 

et al. 2001, p. 17). 

Dispersed recreation is likely to affect 

wolverines, at least in local areas where 

this activity occurs at high intensity in 

wolverine habitat. The magnitude of 

this effect in relation to the wolverine 

DPS is difficult to determine due to a 

lack of information on the effects of 

disturbance on wolverine vital rates, 

behavior, and habitat use, as well as a 

general lack of reliable information 

about the geographic distribution and 

intensity of dispersed recreational use of 

wolverine habitats. For these reasons, 

we conclude that dispersed recreation, 

by itself, is not a threat to wolverines in 

the contiguous United States, but that 

this potential threat may act in concert 

with other threats to contribute to 

wolverine declines. As climate changes 

continue to reduce wolverine habitats, 

dispersed recreational uses such as 

snowmobiling and skiing are likely to 

become more concentrated in any 

remaining snow-covered areas. This is 

an area of concern that deserves more 

scientific investigation as wolverine 

conservation efforts proceed into the 

future. 

Infrastructure 

Infrastructure includes all residential, 

industrial, and governmental 

developments such as buildings, 

houses, oil and gas wells, and ski areas. 

Infrastructure development on private 

lands in the Rocky Mountain West has 

been rapidly increasing in recent years 

and is expected to continue as people 

move to this area for its natural 

amenities (Hansen et al. 2002, p. 151). 

Infrastructure development may affect 

wolverines directly by eliminating 

habitats, or indirectly, by displacing 

wolverines from suitable habitats near 

developments. The latter effect tends to 

be most detrimental to sensitive 

wildlife, because the area of 

displacement may be much larger than 

the area of direct habitat loss. 

Wolverine home ranges generally do 

not occur near human settlements, and 

this separation is likely due both to 

differential habitat selection by 

wolverines and humans and to some 

extent, disturbance-related effects (May 

et al. 2006, pp. 289–292; Copeland et al. 

2007, p. 2211). In one study, wolverines 

did not strongly avoid developed habitat 

within their home ranges (May et al 

2006, p. 289). Wolverines may respond 

positively to human activity and 

developments that are a source of food. 

They scavenge food at dumps in and 

adjacent to urban areas, at trapper 

cabins, and at mines (LeResche and 

Hinman 1973 as cited in Banci 1994, p. 

115; Banci 1994, p. 99). 

Wolverine dispersal may also be 

affected by development. Linkage zones 

are places where animals can find food, 

shelter, and security while moving 

across the landscape between suitable 

habitats. Wolverines prefer to travel in 

habitat that is most similar to habitat 

they use for home-range establishment, 

i.e., alpine habitats that maintain snow 

cover well into the spring (Schwartz et 

al. 2009, p. 3227). Wolverines may 

move large distances in an attempt to 

establish new home ranges, but the 

probability of making such movements 

decreases with increased distance 

between suitable habitat patches, and 

the degree to which the characteristics 

of the habitat to be traversed diverge 

from preferred habitat (Copeland et al. 

2010, entire; Schwartz et al. 2009, p. 

3230). Wolverine populations in the 

northern Rocky Mountains appear to be 

connected to each other at the present 

time through dispersal routes that 

correspond to habitat suitability 

(Schwartz et al. 2009, Figures 4, 5). 

The level of development in these 

linkage areas that wolverines can 

tolerate is unknown, but it appears that 

the current landscape does allow some 


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wolverine dispersal (Schwartz et al. 

2009, Figures 4, 5; Moriarty et al. 2009, 

entire; Inman et al. 2009, pp. 22–28). 

However, contiguous U.S. gene flow 

between populations may not be high 

enough to prevent genetic drift (Cegelski 

et al. 2006, p. 208). Each subpopulation 

within the contiguous United States 

would need an estimated 400 breeding 

pairs, or 1 to 2 effective migrants per 

generation, to ensure long-term genetic 

viability (Cegelski et al. 2006, p. 209). 

Our current understanding of wolverine 

ecology suggests that no subpopulation 

historically or presently at carrying 

capacity would approach 400 breeding 

pairs within the contiguous United 

States (Brock et al. 2007, p. 26); nor is 

the habitat capable of supporting 

anywhere near this number. It is highly 

unlikely that 400 breeding pairs exist in 

the entire contiguous United States. For 

this reason, long-term viability of 

wolverines in the contiguous United 

States requires exchange of individuals 

between blocks of habitat. 

Wolverines are capable of longdistance movements through variable 

and anthropogenically altered terrain, 

crossing numerous transportation 

corridors (Moriarty et al. 2009, entire; 

Inman et al. 2009, pp. 22–28). 

Wolverines are able to successfully 

disperse between habitats, despite the 

level of development that is currently 

taking place in the northern Rocky 

Mountains (Copeland 1996, p. 80; 

Copeland and Yates 2006, pp. 17–36; 

Inman et al. 2007a, pp. 9–10; Pakila et 

al. 2007, pp. 105–109; Schwartz et al. 

2009, Figures 4, 5). Dispersal between 

populations is needed to avoid further 

reduction in genetic diversity; however, 

it is not clear that development or 

human activities are preventing 

wolverine movements between suitable 

habitat patches rather than simply small 

population sizes making movements 

infrequent. Future human developments 

may increase landscape resistance to 

wolverine dispersal; however, we have 

no information to suggest that this 

situation is likely to reach a level of 

impeding wolverine movements within 

the foreseeable future. Infrastructure 

developments that occur within 

wolverine habitat will affect wolverines 

in local areas and those impacts should 

be accounted for during planning 

activities. Infrastructure development, 

by itself, does not threaten the 

wolverine DPS; however, it may act in 

concert with the primary threat of 

climate change to further depress 

wolverine populations as habitats 

become more restricted. 

Transportation Corridors 

Transportation corridors may affect 

wolverines if located in wolverine 

habitat or between habitat patches. If 

located in wolverine habitat, 

transportation corridors result in direct 

loss of habitat and possibly 

displacement of wolverines for some 

distance. Direct mortality due to 

collisions with vehicles is also possible. 

Transportation corridors provide access 

to areas otherwise not affected by 

humans, which exacerbates the effects 

of human disturbance from a variety of 

activities. Outside of wolverine habitat, 

transportation corridors may affect 

wolverines if they present barriers to 

movement between habitat patches or 

result in direct mortality to dispersing 

wolverines. Because wolverines are 

capable of making long-distance 

movements between patches of suitable 

habitat, transportation corridors located 

many miles away from wolverine home 

ranges may affect their ability to 

disperse or recolonize vacant habitats 

after local extirpation events. 

The Trans Canada Highway at Kicking 

Horse Pass in southern British 

Columbia, an important travel corridor 

over the Continental Divide, has a 

negative effect on wolverine movement 

(Austin 1998, p. 30). Wolverines 

partially avoided areas within 100 m 

(328 ft) of the highway, and preferred 

distant sites (greater than 1,100 m (3,608 

ft)). Wolverines that approached the 

highway to cross repeatedly retreated 

and successful crossing occurred in only 

half of the attempts. Where wolverines 

did successfully cross, they used the 

narrowest portions of the highway rightof-way. Although not assessed, 

disturbance-related effects of the 

highway may have been greater in 

summer when traffic volumes were 

higher. A railway with minimal human 

activity, adjacent to the highway, had 

little effect on wolverine movements. 

Wolverines did not avoid, and even 

preferred, compacted, lightly-used ski 

trails in the area. 

In the tri-State area of Idaho, 

Montana, and Wyoming, most crossings 

of Federal or State highways are done by 

subadult wolverines making exploratory 

or dispersal movements (ranges of 

resident adults typically did not contain 

major roads) (Packila et al. 2007, p. 105). 

Roads in the study area, typically 2-lane 

highways or roads with less 

improvement, were not absolute barriers 

to wolverine movement. The wolverine 

that moved to Colorado from Wyoming 

in 2008 successfully crossed Interstate 

80 in southern Wyoming (Inman et al. 

2008, Figure 6). Wolverines in Norway 

successfully cross deep valleys that 

contain light human developments such 

as railway lines, settlements, and roads 

(Landa et al. 1998, p. 454). Wolverines 

in central Idaho avoided portions of a 

study area that contained roads, 

although this was possibly an artifact of 

unequal distribution of roads that 

occurred at low elevations and 

peripheral to the study site (Copeland et 

al. 2007, p. 2211). Wolverines 

frequently used un-maintained roads for 

traveling during the winter, and did not 

avoid trails used infrequently by people 

or active campgrounds during the 

summer. 

At both a site-specific and landscape 

scale, wolverine natal dens were located 

particularly distant from public (greater 

than 7.5 km (4.6 mi)) and private 

(greater than 3 km (1.9 mi)) roads (May 

2007, p. 14–31). Placement of dens away 

from public roads (and away from 

associated human-caused mortality) was 

a positive influence on successful 

reproduction (May 2007, p. 14–31). 

Predictive, broad-scale habitat models, 

developed using historic records of 

wolverine occurrence, indicated that 

roads were negatively associated with 

wolverine occurrence (Rowland et al. 

2003, p. 101). Although wolverines 

appear to avoid transportation corridors 

in their daily movements, the low 

density of these types of structures in 

wolverine habitat leads us to conclude 

that the effects are most likely local in 

scale. Development of transportation 

corridors in linkage areas may inhibit 

wolverine movements between habitat 

patches, potentially reducing 

connectivity among habitat islands. This 

isolating effect has not been measured 

for wolverines and remains theoretical 

at this point in time. Transportation 

corridors, by themselves, do not 

threaten the wolverine DPS, however, 

these corridors may work in concert 

with the primary threat of climate 

change to further depress populations or 

reduce habitat connectivity as habitat 

becomes more restricted. Therefore, we 

consider transportation corridors to be a 

potential threat to the wolverine DPS, in 

concert with the primary threat of 

climate change. 

Land Management 

Effects to wolverines from land 

management actions such as grazing, 

timber harvest, and prescribed fire are 

largely unknown. Wolverines in British 

Columbia used recently logged areas in 

the summer and moose winter ranges 

for foraging (Krebs et al. 2007, pp. 2189– 

2190). Although males did not appear to 

be influenced strongly by the presence 

of roadless areas, the researchers did not 

measure traffic volume, so may have 

been unable to detect responses of males 


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to heavily used roads. In Idaho, 

wolverines used recently burned areas 

despite the loss of canopy cover 

(Copeland 1996, p. 124). 

Intensive management activities such 

as timber harvest and prescribed fire do 

occur in wolverine habitat; however, for 

the most part, wolverine habitat tends to 

be located at high elevations and in 

rugged topography that is unsuitable for 

intensive timber management. Much of 

wolverine habitat is managed by the 

U.S. Forest Service or other Federal 

agencies and is protected from some 

practices or activities such as residential 

development. In addition, much of 

wolverine habitat within the contiguous 

United States is already in a 

management status such as wilderness 

or national park (see Factor D for more 

discussion) that provides some 

protection from management, industrial, 

and recreational activities. Wolverines 

are not thought to be dependent on 

specific vegetation or habitat features 

that might be manipulated by land 

management activities. We conclude 

that land management activities as 

discussed above do not constitute a 

threat to the wolverine DPS. 

Summary of Factor A 

The threat of past, current, and future 

climate change occurs over the entire 

range of the contiguous U.S. population 

of the wolverine. This threat is likely to 

have already reduced the overall areal 

extent and distribution of wolverine 

suitable habitat. Determining whether or 

not wolverine populations have been 

impacted by this threat is complicated 

by the historical extirpation of 

wolverines in the early 20th Century 

followed by recolonization and 

expansion. It is possible that expansion 

of wolverine populations through the 

second half of the 20th Century has 

masked climate change effects that 

would have otherwise reduced 

populations had they existed at 

presettlement levels. So despite the lack 

of detectable population-level impacts, 

it is still likely that habitat is already 

reduced from historic levels due to this 

threat. 

Future climate changes are projected 

to reduce suitable wolverine habitat by 

23 percent by 2045 and 63 percent by 

the time interval between 2070 and 

2099 due to climate warming. This 

reduction will likely result in suitable 

wolverine habitat shifting up mountain 

slopes, and, due to the conical structure 

of mountains, will result in smaller, 

more isolated remaining habitat patches. 

Due to the large size of wolverine home 

ranges, many small mountain ranges are 

likely to lose the ability to support 

wolverine populations. We expect that, 

due to secondary effects of this habitat 

loss such as increased habitat 

fragmentation and isolation, the impacts 

of habitat loss on wolverines will be 

greater than the areal extent of habitat 

loss. 

Deep snow that persists into the 

month of May is essential for wolverine 

reproduction. This life-history need is 

likely to be most sensitive to climate 

changes. Wolverine are vulnerable to 

habitat modification (specifically, 

reduction in persistent spring snow 

cover) due to climate warming in the 

contiguous United States. Further, it is 

likely that year-round wolverine habitat, 

not just denning habitat, will also be 

significantly reduced due to the effects 

of climate warming. Reductions in 

habitat would result in greater habitat 

isolation, reducing the frequency of 

dispersal between habitat patches and 

the likelihood of recolonization after 

local extinction events. This reduced 

dispersal ability is likely to result in loss 

of genetic diversity within remaining 

habitat patches and population loss due 

to demographic stochasticity. The 

contiguous U.S. population of 

wolverines is already very small and 

fragmented and is, therefore, 

particularly vulnerable to these impacts, 

to the extent that the degree of these 

impacts could lead to endangerment of 

the DPS within the foreseeable future. 

The best available scientific and 

commercial information shows that the 

impacts of climate change will continue 

within the foreseeable future. Due to the 

magnitude and extent of the effects of 

climate change, we conclude that 

climate change constitutes a significant 

threat to the contiguous U.S. DPS of the 

wolverine in the foreseeable future. 

Collectively, human activities, 

including dispersed recreation 

activities, infrastructure, and the 

presence of transportation corridors, 

may result in reduced habitat value for 

wolverines. However, the alpine and 

subalpine habitats preferred by 

wolverine typically receive little human 

use relative to lower elevation habitats. 

The evidence at this time does not lead 

us to determine that human activities 

and developments by themselves pose a 

current threat to wolverines in the 

contiguous United States. The majority 

of wolverine habitat (90 percent) occurs 

within Forest Service and National Park 

Service lands that are subject to 

disturbance but not direct habitat loss to 

infrastructure development. The lack of 

information concerning the distribution 

and intensity of human activities, 

especially dispersed recreational 

activities, precludes us from 

determining they currently pose a threat 

to wolverines. 

Wolverines can coexist with some 

modification of their environment, as 

wilderness characteristics such as 

complete lack of motorized use or any 

permanent human presence are likely 

not critical for maintenance of 

populations. It is clear that wolverines 

can coexist with some level of human 

disturbance and habitat modification. 

How much is too much is not known. 

The proximity of wolverine habitats to 

areas heavily or moderately used for 

dispersed recreation needs more study, 

especially where there is overlap during 

the denning season. Effects of these 

activities on wolverine vital rates are 

unknown. 

We know of no examples where large 

areas of habitat, the size of a wolverine’s 

home range or larger, have been 

rendered unsuitable due to human 

activities such as dispersed recreation. 

However, given the sensitivity of 

wolverines during the denning season 

and the increasing intensity of dispersed 

recreational activities in and around 

wolverine habitats, we believe this is an 

area that warrants further study so that 

determinations made in the future may 

be on firmer scientific ground. 

The effects of direct human 

disturbance associated with habitat 

modifications and usage occur 

throughout the range of wolverines. 

Little scientific or commercial 

information indicate effects to 

wolverines from habitat modifications, 

development, or human disturbances 

associated with them. What little 

information exists suggests that 

wolverines can adjust to moderate 

habitat modification, infrastructure 

development, and human disturbance. 

In addition, large amounts of wolverine 

habitat are protected from human 

disturbances and development, either 

legally through wilderness and National 

Park designation, or by being located at 

remote and high-elevation sites. 

Therefore, wolverines are afforded a 

relatively high degree of protection from 

the effects of human activities by the 

nature of their habitat. Wolverines are 

known to successfully disperse long 

distances between habitats through 

human-dominated landscapes and 

across transportation corridors. The 

current level of residential, industrial, 

and transportation development in the 

western United States does not appear 

to have precluded the long-distance 

dispersal movements that wolverines 

require for maintenance of genetic 

diversity. 

The impacts of climate change 

constitute a threat to the contiguous 

U.S. DPS of the wolverine, and will 

likely be irreversible within the 

foreseeable future. Due to the magnitude 


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and extent of the effects of climate 

change, we find that the contiguous U.S. 

DPS of the North American wolverine is 

likely to become in danger of extinction 

in the foreseeable future due to 

destruction, modification, and 

curtailment of its habitat and range by 

climate change. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

Over much of recent history, trapping 

has been a primary cause of wolverine 

mortality (Banci 1994, p. 108; Krebs et 

al. 2004, p. 497; Lofroth and Ott 2007, 

pp. 2196–2197; Squires et al. 2007, p. 

2217). Unregulated trapping is believed 

to have played a role in the historic 

decline of wolverines in North America 

in the late 1800s and early 1900s (Hash 

1987, p. 580). Wolverines are especially 

vulnerable to targeted trapping and 

predator reduction campaigns due to 

their habit of ranging widely in search 

of carrion, which would bring them into 

frequent contact with poison baits and 

traps (Copeland 1996, p. 78; Inman et al. 

2007a, pp. 4–10; Packila et al. 2007, p. 

105; Squires et al. 2007, p. 2219). 

Human-caused mortality of 

wolverines is likely additive to natural 

mortality due to the low reproductive 

rate and relatively long life expectancy 

of wolverines (Krebs et al. 2004, p. 499; 

Lofroth and Ott 2007, pp. 2197–2198; 

Squires et al. 2007, pp. 2218–2219). 

This means that trapped populations 

likely live at densities that are lower 

than carrying capacity, and may need to 

be reinforced by recruits from 

untrapped populations to maintain 

population viability and persistence. 

A study in British Columbia 

determined that, under a regulated 

trapping regime, trapping mortality in 

15 of 71 wolverine population units was 

unsustainable, and that populations in 

those unsustainable population units 

are dependent on immigration from 

neighboring populations or untrapped 

refugia (Lofroth and Ott 2007, pp. 2197– 

2198). Similarly, in southwestern 

Montana, intensive legal trapping in 

isolated mountain ranges reduced local 

populations and was the dominant form 

of mortality for the duration of the study 

(Squires et al. 2007, pp. 2218–2219). 

The harvest levels observed, which 

included two pregnant females in a 

small mountain range, could have 

significant negative effects on a small 

population (Squires et al. 2007, p. 

2219). Harvest refugia, such as national 

parks and large wilderness, are 

important to wolverine persistence on 

the landscape because they can serve as 

sources of surplus individuals to bolster 

trapped populations (Squires et al. 

2007, p. 2219; Krebs and Ott 2004, p. 

500). Glacier National Park, though an 

important refuge for a relatively robust 

population of wolverines, was still 

vulnerable to trapping because most 

resident wolverine home ranges 

extended into large areas outside the 

Park (Squires et al. 2007, p. 2219). 

Despite the impacts of trapping on 

wolverines in the past, trapping is no 

longer a threat within most of the 

wolverine range in the contiguous 

United States. Montana is the only State 

where wolverine trapping is still legal. 

Before 2004, average wolverine harvest 

was 10.5 wolverines per year. Due to 

preliminary results of the study reported 

in Squires et al. (2007, pp. 2213–2220), 

the Montana Department of Fish, 

Wildlife, and Parks adopted new 

regulations for the 2004–2005 trapping 

season that divided the State into three 

units, with the goal of spreading the 

harvest more equitably throughout the 

State. 

For the 2008–2009 trapping season, 

Montana Department of Fish, Wildlife, 

and Parks adjusted its wolverine 

trapping regulations again to further 

increase the geographic control on 

harvest to prevent concentrated trapping 

in any one area, and to completely stop 

trapping in isolated mountain ranges 

where small populations are most 

vulnerable (Montana Department of Fish 

Wildlife and Parks 2010, pp. 8–11). 

Their new regulations spread harvest 

across three geographic units (the 

Northern Continental Divide area, the 

Greater Yellowstone area, and the 

Bitterroot Mountains), and establish a 

statewide limit of 5 wolverines. The 

2008–2009 and 2009–2010 trapping 

seasons have resulted in four and three 

wolverines harvested, respectively 

(Montana Department of Fish Wildlife 

and Parks 2010, pp. 8–11). Under the 

current regulations, no more than three 

female wolverines can be legally 

harvested each year, and harvest in the 

more vulnerable isolated mountain 

ranges is prohibited. 

Montana Department of Fish, 

Wildlife, and Parks conducts yearly 

monitoring using track surveys. Their 

protocol does not utilize verification 

methods such as DNA collection or 

camera stations to confirm 

identifications. Consequently, 

misidentifications are likely to occur. 

Given the relative rarity of wolverines 

and the relative abundance of other 

species with which they may be 

confused, such as bobcats, lynx, and 

bears, lack of certainty of identifications 

of tracks makes it highly likely that the 

rare species is over-represented in 

unverified tracking records (McKelvey 

et al. 2008, entire). The Montana 

Department of Fish, Wildlife, and Parks 

wolverine track survey information does 

not meet our standard for verifiable or 

documented occurrence records 

described in the geographic distribution 

section, and we have not relied on this 

information in this finding. 

Montana wolverine populations have 

rebounded from historic lows in the 

early 1900s while at the same time being 

subject to regulated trapping (Aubry et 

al. 2007, p. 2151; Montana Department 

of Fish, Wildlife, and Parks 2007, p. 1). 

In fact, much of the wolverine 

expansion that we have described above 

took place under less-restrictive harvest 

regulations than are in place today. 

Through their refinement of harvest 

regulations over the past 10 years, 

Montana Department of Fish, Wildlife, 

and Parks has demonstrated its 

commitment to adjust harvest 

management when evidence indicates it 

is necessary for conserving wolverine 

populations. Therefore, we conclude 

that, in the absence of other threats, 

harvest would not be likely to threaten 

State-wide wolverine populations in 

Montana, or to threaten the continued 

existence of the wolverine population in 

the contiguous United States. However, 

the additive mortality caused by 

trapping could become a concern in the 

future as the size of the wolverine 

population shrinks in response to the 

loss of habitat due to climate change 

described above. 

Current levels of incidental trapping 

(i.e., capture in traps set for species 

other than wolverine) and poisoning 

have been suggested to be a threat to 

wolverines, but no supporting 

information for this assertion is 

available. 

Summary of Factor B 

Wolverine harvest affects one of the 

four States within the current range of 

North American wolverines in the 

contiguous United States. However, the 

State of Montana contains most of the 

habitat and wolverines that exist in the 

four States, and regulates trapping to 

reduce the impact of harvest on 

wolverine populations. We do not 

believe that the level of harvest in 

Montana, by itself, is a threat that causes 

the species within the contiguous 

United States to be in danger of 

extinction or likely to become in danger 

of extinction in the foreseeable future. 

Harvest, when combined with the 

other threats outlined in this finding, 

may contribute to the likelihood that the 

wolverine will become extirpated in the 

foreseeable future by increasing the 

speed with which small populations of 

wolverine are lost from isolated 

habitats, and also by increasing 


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mortality levels for dispersing 

wolverines that are required to maintain 

the genetics and demographics of 

wolverine populations in the contiguous 

United States. The willingness of the 

Montana Department of Fish, Wildlife, 

and Parks to adjust wolverine harvest 

management in reaction to new 

scientific information on the status of 

wolverines leads us to believe that the 

agency will continue to adjust harvest 

levels as needed, including suspension 

of harvest altogether should populations 

decline. 

Factor C. Disease or Predation 

Limited information is currently 

available on the potential effects of 

disease on wolverine populations. 

Wolverines are sometimes killed by 

wolves, black bears, and puma 

(Burkholder 1962, p. 264; Hornocker 

and Hash 1981, p. 1296; Copeland 1996, 

p. 44–46; Inman et al. 2007d, p. 89). In 

addition, wolverine reproductive dens 

are likely subject to predation, although 

so few dens have been discovered in 

North America that determining the 

intensity of this predation is not 

possible. 

Summary of Factor C 

Wolverine mortality from predation 

and disease do not appear to be above 

natural or sustainable levels, such that 

these factors would cause the species 

within the contiguous United States to 

be in danger of extinction or likely to 

become in danger of extinction in the 

foreseeable future. 

Factor D. Inadequacy of Existing 

Regulatory Mechanisms 

The majority (95 percent) of 

wolverine habitat currently occupied by 

wolverine populations in the lower 

contiguous United States is Federally 

owned and managed, mostly (90 

percent) by the Forest Service. An 

estimated 126,302 km 2 (49,258 mi 2) of 

wolverine habitat occurs in Montana, 

Idaho, and Wyoming. Of that, 120,000 

km 2 (46,332 mi 2) is in Federal 

ownership and 109,000 km 2 (42,085 

mi 2) of that is managed by the Forest 

Service. Additionally, 33,263 km 

(12,973 mi 2) (26.3 percent) occurs in 

designated wilderness; 4,180 km 2

(1,630 mi 2) (3.3 percent) are in 

wilderness study areas. An additional 

8,432 km 2 (3,288 mi 2) (6.7 percent) are 

within national parks (Brock et al. 2007, 

pp. 33–35; Inman 2007b, pers. comm.). 

Thus, a total of 36.3 percent of the 

estimated wolverine habitat in the threeState area occurs in locations with high 

levels of protection. 

No Federal or State regulatory 

mechanisms exist that address the threat 

of modification of wolverine habitat due 

to climate change. Several mechanisms 

exist that protect wolverine from other 

forms of disturbance and from 

overutilization from harvesting; these 

are described in more detail below. 

Federal Laws and Regulations 

The Wilderness Act 

The Forest Service and National Park 

Service both manage lands designated 

as wilderness areas under the 

Wilderness Act of 1964 (16 U.S.C. 1131– 

1136). Within these areas, the 

Wilderness Act states the following: (1) 

New or temporary roads cannot be built; 

(2) there can be no use of motor 

vehicles, motorized equipment, or 

motorboats; (3) there can be no landing 

of aircraft; (4) there can be no other form 

of mechanical transport; and (5) no 

structure or installation may be built. A 

large amount of suitable wolverine 

habitat occurs within Federal 

wilderness areas in the United States 

(Inman, personal communication 

2007b). As such, a large proportion of 

existing wolverine habitat is protected 

from direct loss or degradation by the 

prohibitions of the Wilderness Act. 

National Environmental Policy Act 

All Federal agencies are required to 

adhere to the National Environmental 

Policy Act (NEPA) of 1970 (42 U.S.C. 

4321 et seq.) for projects they fund, 

authorize, or carry out. The Council on 

Environmental Quality’s regulations for 

implementing NEPA (40 CFR parts 

1500–1518) state that agencies shall 

include a discussion on the 

environmental impacts of the various 

project alternatives (including the 

proposed action), any adverse 

environmental effects which cannot be 

avoided, and any irreversible or 

irretrievable commitments of resources 

involved (40 CFR part 1502). The NEPA 

itself is a disclosure law, and does not 

require subsequent minimization or 

mitigation measures by the Federal 

agency involved. Although Federal 

agencies may include conservation 

measures for wolverines as a result of 

the NEPA process, any such measures 

are typically voluntary in nature and are 

not required by the statute. 

Additionally, activities on non-Federal 

lands are subject to NEPA if there is a 

Federal nexus. 

For example, wolverines are 

designated as a sensitive species by the 

Forest Service, which requires that 

effects to wolverines be considered in 

documentation completed under NEPA. 

NEPA does not itself regulate activities 

that might affect wolverines, but it does 

require full evaluation and disclosure of 

information regarding the effects of 

contemplated Federal actions on 

sensitive species and their habitats. 

National Forest Management Act 

Under the National Forest 

Management Act of 1976, as amended 

(16 U.S.C. 1600–1614), the Forest 

Service shall strive to provide for a 

diversity of plant and animal 

communities when managing national 

forest lands. Individual national forests 

may identify species of concern that are 

significant to each forest’s biodiversity. 

It is unknown what level of protection, 

if any, each of the individual national 

forests offer for wolverines. In many of 

the States in which wolverines are 

found, wolverines occur in wilderness 

areas and are thus protected under the 

Wilderness Act. Outside of wilderness 

but still on Forest Service-managed 

lands, wolverines occur mainly in 

alpine areas, which are sensitive to 

negative habitat alterations. Their 

habitat is generally offered more 

protections from harvest or road 

building than would otherwise be the 

case in lowland areas. 

National Park Service Organic Act 

The NPS Organic Act of 1916 (16 

U.S.C. 1 et seq.), as amended, states that 

the NPS ‘‘shall promote and regulate the 

use of the Federal areas known as 

national parks, monuments, and 

reservations to conserve the scenery and 

the national and historic objects and the 

wildlife therein and to provide for the 

enjoyment of the same in such manner 

and by such means as will leave them 

unimpaired for the enjoyment of future 

generations.’’ Where wolverines occur in 

National Parks, they and their habitats 

are protected from large-scale loss or 

degradation due to the Park Service’s 

mandate to ‘‘* * * conserve scenery 

* * * and wildlife * * * [by leaving] 

them unimpaired.’’ 

Clean Air Act of 1970 

The petitioners claim that wolverines 

are threatened by a lack of regulatory 

mechanisms to curb greenhouse gases 

that contribute to global temperature 

rises (Wolf et al. 2007, p. 50). As stated 

earlier under Factor A, our status review 

did reveal information that increased 

temperatures and loss of persistent 

spring snow are a significant threat to 

wolverines across the DPS range in the 

foreseeable future. No existing 

regulatory mechanisms adequately 

address global climate change. The 

Clean Air Act of 1970 (42 U.S.C. 7401 

et seq.), as amended, requires the 

Environmental Protection Agency (EPA) 

to develop and enforce regulations to 

protect the general public from exposure 


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to airborne contaminants that are known 

to be hazardous to human health. In 

2007, the Supreme Court ruled that 

gases that cause global warming are 

pollutants under the Clean Air Act, and 

that the EPA has the authority to 

regulate carbon dioxide and other heattrapping gases (Massachusetts et al. v. 

EPA 2007 [Case No. 05–1120]). The EPA 

published a regulation to require 

reporting of greenhouse gas emissions 

from fossil fuel suppliers and industrial 

gas suppliers, direct greenhouse gas 

emitters, and manufacturers of heavyduty and off-road vehicles and engines 

(74 FR 56260; October 30, 2009). The 

rule, effective December 29, 2009, does 

not require control of greenhouse gases; 

rather it requires only that sources 

above certain threshold levels monitor 

and report emissions (74 FR 56260; 

October 30, 2009). On December 7, 

2009, the EPA found under section 

202(a) of the Clean Air Act that the 

current and projected concentrations of 

six greenhouse gases in the atmosphere 

threaten public health and welfare. The 

finding itself does not impose 

requirements on any industry or other 

entities but is a prerequisite for any 

future regulations developed by the 

EPA. At this time, it is not known what 

regulatory mechanisms will be 

developed in the future as an outgrowth 

of the finding or how effective they 

would be in addressing climate change. 

State Laws and Regulations 

State Comprehensive Wildlife 

Conservation Strategies and State 

Environmental Policy and Protection 

Acts 

The wolverine is listed as State 

Endangered in Washington, California, 

and Colorado. In Idaho and Wyoming it 

is designated as a protected nongame 

species (Idaho Department of Fish and 

Game 2010, p. 4; Wyoming Game and 

Fish 2005, p. 2). Oregon, while currently 

not considered to have any individuals 

other than possible unsuccessful 

dispersers, has a closed season on 

trapping of wolverines. These 

designations largely protect the 

wolverine from mortality due to hunting 

and trapping. In Montana, the wolverine 

is classified as a regulated furbearer 

(Montana Fish, Wildlife, and Parks 

2010, p. 8). Montana is the only State in 

the contiguous United States where 

wolverine trapping is still legal. 

Wolverines receive some protection 

under State laws in Washington, 

California, Idaho, Montana, Wyoming, 

and Colorado. Each State’s fish and 

wildlife agency has some version of a 

State Comprehensive Wildlife 

Conservation Strategy (CWCS) in place. 

These strategies, while not State or 

national legislation can help prioritize 

conservation actions within each State. 

Named species and habitats within each 

CWCS may receive focused attention 

during State Environmental Protection 

Act (SEPA) reviews as a result of being 

included in a State’s CWCS. However, 

only Washington, California, and 

Montana appear to have SEPA-type 

regulations in place. In addition, each 

State’s fish and wildlife agency often 

specifically names or implies protection 

of wolverines in their hunting and 

trapping regulations. Only the State of 

Montana currently allows wolverine 

harvest. 

Before 2004, the Montana Department 

of Fish, Wildlife, and Parks regulated 

wolverine harvest through the licensing 

of trappers, a bag limit of one wolverine 

per year per trapper, and no statewide 

limit. Under this management, average 

wolverine harvest was 10.5 wolverines 

per year. Due to preliminary results of 

the study reported in Squires et al. 

(2007, pp. 2213–2220), Montana 

Department of Fish, Wildlife, and Parks 

adopted new regulations for the 2004– 

2005 trapping season that divided the 

State into three units with the goal of 

spreading the harvest more equitably 

throughout the State. In 2008, Montana 

Department of Fish, Wildlife, and Parks 

further refined their regulations to 

prohibit trapping in isolated mountain 

ranges, and reduced the overall 

statewide harvest to 5 wolverines with 

a statewide female harvest limit of 3. We 

conclude that trapping in Montana, by 

itself, is not a threat to the wolverine 

DPS, but that by working in concert 

with the primary threat of climate 

change, the trapping program may 

contribute to population declines 

caused by other threats. Therefore, we 

conclude that wolverine harvest is a 

secondary threat to wolverines. 

Summary of Factor D 

The existing regulatory mechanisms 

appear to protect wolverine from several 

of the threats described in Factors A 

through C above. Specifically, State 

regulations for wolverine harvest appear 

to be sufficient to prohibit range-wide 

overutilization from hunting and 

trapping in the absence of other threats. 

Federal ownership of much of occupied 

wolverine habitat protects the species 

from direct losses of habitat and 

provides further protection from many 

of the forms of disturbance described 

above. Wolverines can use habitats 

affected by moderate levels of human 

disturbance, and additional protection 

is afforded wolverines by the significant 

portion of their range that occurs in 

designated wilderness and national 

parks. The current regulatory regime 

does not address the potential impacts 

of dispersed winter recreation; however, 

at this time the available information 

does not suggest that dispersed winter 

recreation is a threat. That being the 

case, all of these potential threats are 

likely to have local impacts on 

wolverines, and cumulatively, they may 

act in concert with the primary threat of 

climate change to threaten wolverine 

populations. Therefore, we conclude it 

is appropriate to view them as 

secondary threats to the wolverine DPS. 

Our review of the regulatory 

mechanisms in place at the national and 

State level demonstrates that the shortterm, site-specific threats to wolverine 

from direct loss of habitat, disturbance 

by humans, and direct mortality from 

hunting and trapping are, for the most 

part, adequately addressed through 

State and Federal regulatory 

mechanisms. However, as described 

under Factor A, the primary threat with 

the greatest severity and magnitude of 

impact to the species is loss of habitat 

due to continuing climate warming. No 

known regulatory mechanisms are 

currently in place at the national or 

international level that effectively 

address this threat to wolverine habitat 

from climate change. Therefore, the 

current inadequacy of regulatory 

mechanisms to protect wolverines and 

their habitat is a threat to the DPS. 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

Small Population Size 

Wolverines in the contiguous United 

States are thought to be derived from a 

recent re-colonization event after they 

were extirpated from the area in the 

early 20th century (Aubry et al. 2007, 

Table 1, Michael Schwartz, pers. 

comm.). Consequently, wolverine 

populations in the contiguous United 

States have reduced genetic diversity 

relative to larger Canadian populations 

as a result of founder effects or 

inbreeding (Schwartz et al. 2009, pp. 

3228–3230). As described in the DPS 

analysis above, wolverine effective 

population size in the contiguous 

United States is exceptionally low 

(Schwartz 2007, pers. comm.) and is 

below what is thought to be adequate for 

short-term maintenance of genetic 

diversity. Loss of genetic diversity can 

lead to inbreeding depression and is 

associated with increased risk of 

extinction (Allendorf and Luikart 2007, 

pp. 338–343). Effective population size 

is important because it determines rates 

of loss of genetic variation, fixation of 

deleterious alleles, and the rate of 


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inbreeding. Small effective population 

sizes are caused by small actual 

population size (census size), or by 

other factors that limit the genetic 

contribution of portions of the 

population, such as polygamous mating 

systems. Populations may increase their 

effective size by increasing census size 

or by the regular exchange of genetic 

material with other populations through 

inter-population mating. Populations 

with small effective population sizes 

show reductions in population growth 

rates and increases in extinction 

probabilities (Leberg 1990, p. 194; 

Jimenez et al. 1994, pp. 272–273; 

Newman and Pilson 1997, p. 360; 

Saccheri et al. 1998, p. 492; Reed and 

Bryant 2000, p. 11; Schwartz and Mills 

2005, p. 419; Hogg et al. 2006, p. 1495, 

1498; Allendorf and Luikart 2007, pp. 

338–342). 

The concern with the low effective 

population size was highlighted in a 

recent analysis which determined that 

without immigration from other 

populations at least 400 breeding pairs 

would be necessary to sustain the longterm genetic viability of the contiguous 

U.S. wolverine population (Cegelski et 

al. 2006, p. 197). However, the entire 

population is likely only 250 to 300 

(Inman 2010b, pers. comm.), with a 

substantial number of these being 

unsuccessful breeders or nonbreeding 

subadults. 

Genetic studies demonstrate the 

essential role that genetic exchange 

plays in maintaining genetic diversity in 

small wolverine populations. The 

concern that low effective population 

size would result in negative effects is 

already being realized for the 

contiguous U.S. population of 

wolverine. Genetic drift has already 

occurred in subpopulations of the 

contiguous United States: wolverines 

here contained 3 of 13 haplotypes found 

in Canadian populations (Kyle and 

Strobeck 2001, p. 343; Cegelski et al. 

2003, pp. 2914–2915; Cegelski et al. 

2006, p. 208; Schwartz et al. 2007, p. 

2176; Schwartz et al. 2009, p. 3229). 

The haplotypes found in these 

populations were a subset of those in 

the larger Canadian population, 

indicating that genetic drift had caused 

a loss of genetic diversity. One study 

found that a single haplotype dominated 

the northern Rocky Mountain wolverine 

population, with 71 of 73 wolverines 

sampled expressing that haplotype 

(Schwartz et al. 2007, p. 2176). The 

reduced number of haplotypes indicates 

not only that genetic drift is occurring 

but some level of genetic separation; if 

these populations were freely 

interbreeding, they would share more 

haplotypes (Schwartz et al. 2009, p. 

3229). The reduction of haplotypes is 

likely a result of the fragmented nature 

of wolverine habitat in the United States 

and is consistent with an emerging 

pattern of reduced genetic variation at 

the southern edge of the range 

documented in a suite of boreal forest 

carnivores (Schwartz et al. 2007, p. 

2177). 

Immigration of wolverines from 

Canada is not likely to bolster the 

genetic diversity of wolverines in the 

contiguous United States. There is an 

apparent lack of connectivity between 

wolverine populations in Canada and 

the United States based on genetic data 

(Schwartz et al. 2009, pp. 3228–3230). 

The apparent loss of connectivity 

between wolverines in the northern 

Rocky Mountains and Canada prevents 

the influx of genetic material needed to 

maintain or increase the genetic 

diversity in the contiguous United 

States. The continued loss of genetic 

diversity may lead to inbreeding 

depression, potentially reducing the 

species’ ability to persist through 

reduced reproductive output or reduced 

survival. Currently, the cause for this 

lack of connectivity is uncertain, and 

existing regulatory mechanisms may be 

inadequate to address population 

connectivity. Wolverine habitat appears 

to be well-connected across the border 

region (Copeland et al. 2010, Figure 2) 

and there are few man-made 

obstructions such as transportation 

corridors or alpine developments. 

However, this lack of genetically 

detectable connectivity may be related 

to harvest management in southern 

Canada. The current inadequacy of 

existing regulatory mechanisms to 

address connectivity across the 

international boundary may pose a risk 

to wolverines in the contiguous United 

States in the future through reduced 

effective population size resulting in 

potential loss of genetic diversity 

through inbreeding. 

Summary of Factor E 

Small population size and inbreeding 

depression are potential threats to 

wolverines in the contiguous United 

States. There is good evidence that 

genetic diversity is lower in wolverines 

in the DPS than it is in the more 

contiguous habitat in Canada and 

Alaska. The significance of this lower 

genetic diversity to wolverine 

conservation is unknown. We do not 

discount the possibility that loss of 

genetic diversity could be negatively 

affecting wolverines now and will 

continue to do so in the future. It is 

important to point out however, that 

wolverine populations in the DPS area 

are thought to be the result of 

colonization events that have occurred 

since the 1930s. Such recent 

colonizations by relatively few 

individuals and subsequent population 

growth are likely to have resulted in 

founder effects, which could have 

contributed to the low genetic diversity. 

The threat of small population sizes and 

low genetic diversity is likely to become 

more significant if populations become 

smaller and more isolated, as predicted 

due to climate changes. Restoration of 

connectivity with Canadian populations 

may require international cooperation to 

establish appropriate control of 

exploitation in the international border 

region. Therefore, it is our 

determination that small population 

size and inbreeding depression are a 

secondary threat to the DPS that may 

contribute to wolverine declines, 

especially as projected climate changes 

reduce overall habitat size and 

connectivity between habitat patches. 

Finding 

As required by the Act, we conducted 

a review of the status of the DPS and 

considered the five factors in assessing 

whether wolverines in the contiguous 

United States are threatened or 

endangered throughout all or a 

significant portion of their range. We 

examined the best scientific and 

commercial information available 

regarding the past, present, and future 

threats faced by wolverines. We 

reviewed the petition, information 

available in our files, other available 

published and unpublished 

information, and we consulted with 

wolverine and wolverine habitat experts 

and other Federal, State, and tribal 

agencies. 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 

warrants 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 is not 

sufficient to compel a finding that 


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listing is appropriate; we require 

evidence that these factors are operative 

threats that act on the species to the 

point that the species meets the 

definition of threatened or endangered 

under the Act. 

This status review identified threats 

to the contiguous U.S. population of the 

North American wolverine attributable 

to Factors A, B, D, and E. The primary 

threat to the DPS is from habitat and 

range loss due to climate warming 

(Factor A). Wolverines inhabit habitats 

with near-arctic conditions wherever 

they occur. In the contiguous United 

States, wolverine habitat is restricted to 

high-elevation areas in the West. 

Wolverines are dependent on deep 

persistent snow cover for successful 

denning, and they concentrate their 

year-round activities in areas that 

maintain deep snow into spring and 

cool temperatures throughout summer. 

Wolverines in the contiguous United 

States exist as small and semi-isolated 

subpopulations in a larger 

metapopulation that requires regular 

dispersal of wolverines between habitat 

patches to maintain itself. These 

dispersers achieve both genetic 

enrichment and demographic support of 

recipient populations. Climate changes 

are predicted to reduce wolverine 

habitat and range by 23 percent over the 

next 30 years and 63 percent over the 

next 75 years, rendering remaining 

wolverine habitat significantly smaller 

and more fragmented. We anticipate 

that, by 2045, maintenance of the 

contiguous U.S. wolverine population 

in the currently occupied area will 

require human intervention to facilitate 

genetic exchange and possibly also 

facilitate metapopulation dynamics by 

moving individuals between habitat 

patches that are no longer accessed 

regularly by dispersers. Other threats are 

minor in comparison to the driving 

primary threat of climate change; 

however, they could become significant 

when working in concert with climate 

change if they further suppress an 

already stressed population. These 

secondary threats include harvest 

(Factor B), disturbance, infrastructure, 

and transportation corridors (Factor D), 

and demographic stochasticity and loss 

of genetic diversity due to small 

effective population sizes (Factor E). All 

of these factors affect wolverines across 

their current range in the contiguous 

United States 

On the basis of the best scientific and 

commercial data available, we find that 

the petitioned action, to list the North 

American wolverine population in the 

contiguous United States as threatened 

or endangered is warranted. We arrive at 

this determination due to the current 

status of wolverines in the contiguous 

United States, which exist as a small 

(250–300 individuals) and genetically 

depauperate (3 of 13 haplotypes) 

metapopulation with limited dispersal 

between subpopulations. This 

information, when combined with 

information about the primary and 

secondary threats indicates that 

wolverines are likely to lose 63 percent 

of their current habitat area over the 

next century. We will make a 

determination on the status of the 

species as threatened or endangered 

when we do a proposed listing 

determination. However, as explained 

in more detail below, an immediate 

proposal of a regulation implementing 

this action is precluded by higher 

priority listing actions, and progress is 

being made to add or remove qualified 

species from the Lists of Endangered 

and Threatened Wildlife and Plants. 

We reviewed the available 

information to determine if the existing 

and foreseeable threats render the 

species at risk of extinction now such 

that issuing an emergency regulation 

temporarily listing the species under 

section 4(b)(7) of the Act is warranted. 

We determined that issuing an 

emergency regulation temporarily 

listing the species is not warranted for 

this species at this time, because the 

effects of climate warming on 

wolverines and their habitat are 

expected to unfold over many years and 

populations currently appear to be 

stable or expanding. However, if at any 

time we determine that issuing an 

emergency regulation temporarily 

listing the North American wolverine in 

the contiguous United States is 

warranted, we will initiate this action at 

that time. 

Listing Priority Number 

The Service adopted guidelines on 

September 21, 1983 (48 FR 43098), to 

establish a rational system for utilizing 

available resources for the highest 

priority species when adding species to 

the Lists of Endangered or Threatened 

Wildlife and Plants or reclassifying 

species listed as threatened to 

endangered status. These guidelines, 

titled ‘‘Endangered and Threatened 

Species Listing and Recovery Priority 

Guidelines’’ address the immediacy and 

magnitude of threats, and the level of 

taxonomic distinctiveness by assigning 

priority in descending order to 

monotypic genera (genus with one 

species), full species, and subspecies (or 

equivalently, distinct population 

segments of vertebrates). 

As a result of our analysis of the best 

available scientific and commercial 

information, we assigned wolverines in 

the contiguous United States a Listing 

Priority Number (LPN) of 6 based on our 

finding that the DPS faces threats that 

are of high magnitude but that are not 

imminent. The primary threat includes 

the present or threatened destruction, 

modification, or curtailment of 

wolverine habitat from climate change; 

and the secondary threats are associated 

with Factors B, D, and E. 

Under the Service’s guidelines, the 

magnitude of threat is the first criterion 

we look at when establishing a listing 

priority. The guidance indicates that 

species with the highest magnitude of 

threat are those species facing the 

greatest threats to their continued 

existence. These species receive the 

highest listing priority. We consider the 

threats that wolverines face to be high 

in magnitude because the threat of 

climate change is present throughout 

the range of the DPS. 

Under our LPN guidelines, the second 

criterion we consider in assigning a 

listing priority is the immediacy of 

threats. This criterion is intended to 

ensure that the species facing actual, 

identifiable threats are given priority 

over those species for which threats are 

only potential or that are intrinsically 

vulnerable but are not known to be 

presently facing such threats. The 

primary threat facing the DPS is not 

imminent. The threat from climate 

change is reasonably certain to occur, 

and its effects may be particularly acute 

for small, isolated populations, but we 

have no evidence that these effects are 

imminent (ongoing). The other 

identified threats were determined only 

to be potential threats when acting in 

concert with the driving threat of 

climate change. Therefore, based on our 

LPN Policy, the threats are not 

imminent (ongoing). 

The third criterion in our LPN 

guidelines is intended to devote 

resources to those species representing 

highly distinctive or isolated gene pools 

as reflected by taxonomy. We 

determined wolverines of the 

contiguous United States are a valid 

DPS according to our DPS Policy. 

Therefore, under our LPN guidance, the 

wolverine in the contiguous United 

States is assigned a lower priority than 

a species in a monotypic genus or a full 

species that faces the same magnitude 

and imminence of threats. 

Therefore, we assigned the DPS an 

LPN of 6 based on our determination 

that the DPS faces threats that are 

overall of high magnitude but are not 

imminent. We will continue to monitor 

the threats to wolverines in the 

contiguous United States, and the DPS’ 

status on an annual basis, and should 

the magnitude or the imminence of the 


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threats change, we will revisit our 

assessment of LPN. 

Preclusion and Expeditious Progress 

Preclusion is a function of the listing 

priority of a species in relation to the 

resources that are available and 

competing demands for those resources. 

Thus, in any given fiscal year (FY), 

multiple factors dictate whether it will 

be possible to undertake work on a 

proposed listing regulation or whether 

promulgation of such a proposal is 

warranted but precluded by higher 

priority listing actions. 

The resources available for listing 

actions are determined through the 

annual Congressional appropriations 

process. The appropriation for the 

Listing Program is available to support 

work involving the following listing 

actions: Proposed and final listing rules; 

90-day and 12-month findings on 

petitions to add species to the Lists of 

Endangered and Threatened Wildlife 

and Plants (Lists) or to change the status 

of a species from threatened to 

endangered; annual determinations on 

prior ‘‘warranted but precluded’’ petition 

findings as required under section 

4(b)(3)(C)(i) of the Act; critical habitat 

petition findings; proposed and final 

rules designating critical habitat; and 

litigation-related, administrative, and 

program-management functions 

(including preparing and allocating 

budgets, responding to congressional 

and public inquiries, and conducting 

public outreach regarding listing and 

critical habitat). The work involved in 

preparing various listing documents can 

be extensive and may include, but is not 

limited to: Gathering and assessing the 

best scientific and commercial data 

available and conducting analyses used 

as the basis for our decisions; writing 

and publishing documents; and 

obtaining, reviewing, and evaluating 

public comments and peer review 

comments on proposed rules and 

incorporating relevant information into 

final rules. The number of listing 

actions that we can undertake in a given 

year also is influenced by the 

complexity of those listing actions; that 

is, more complex actions generally are 

more costly. For example, during the 

past several years, the cost (excluding 

publication costs) for preparing a 12- 

month finding, without a proposed rule, 

has ranged from approximately $11,000 

for one species with a restricted range 

and involving a relatively 

uncomplicated analysis to $305,000 for 

another species that is wide-ranging and 

involving a complex analysis. 

We cannot spend more than is 

appropriated for the Listing Program 

without violating the Anti-Deficiency 

Act (see 31 U.S.C. 1341(a)(1)(A)). In 

addition, in FY 1998 and for each FY 

since then, Congress has placed a 

statutory cap on funds which may be 

expended for the Listing Program, equal 

to the amount expressly appropriated 

for that purpose in that FY. This cap 

was designed to prevent funds 

appropriated for other functions under 

the Act (for example, recovery funds for 

removing species from the Lists), or for 

other Service programs, from being used 

for Listing Program actions (see House 

Report 105–163, 105th Congress, 1st 

Session, July 1, 1997). 

Recognizing that designation of 

critical habitat for species already listed 

would consume most of the overall 

Listing Program appropriation, Congress 

also put a critical habitat subcap in 

place in FY 2002 and has retained it 

each subsequent year to ensure that 

some funds are available for other work 

in the Listing Program: ‘‘The critical 

habitat designation subcap will ensure 

that some funding is available to 

address other listing activities’’ (House 

Report No. 107—103, 107th Congress, 

1st Session, June 19, 2001). In FY 2002 

and each year until FY 2006, the Service 

has had to use virtually the entire 

critical habitat subcap to address courtmandated designations of critical 

habitat, and consequently none of the 

critical habitat subcap funds have been 

available for other listing activities. In 

some FYs since 2006, we have been able 

to use some of the critical habitat 

subcap funds to fund proposed listing 

determinations for high-priority 

candidate species. In other FYs, while 

we were unable to use any of the critical 

habitat subcap funds to fund proposed 

listing determinations, we did use some 

of this money to fund the critical habitat 

portion of some proposed listing 

determinations so that the proposed 

listing determination and proposed 

critical habitat designation could be 

combined into one rule, thereby being 

more efficient in our work. In FY 2011 

we anticipate that we will be able to use 

some of the critical habitat subcap funds 

to fund proposed listing determinations. 

We make our determinations of 

preclusion on a nationwide basis to 

ensure that the species most in need of 

listing will be addressed first and also 

because we allocate our listing budget 

on a nationwide basis. Through the 

listing cap, the critical habitat subcap, 

and the amount of funds needed to 

address court-mandated critical habitat 

designations, Congress and the courts 

have in effect determined the amount of 

money available for other listing 

activities nationwide. Therefore, the 

funds in the listing cap, other than those 

needed to address court-mandated 

critical habitat for already listed species, 

set the limits on our determinations of 

preclusion and expeditious progress. 

Congress identified the availability of 

resources as the only basis for deferring 

the initiation of a rulemaking that is 

warranted. The Conference Report 

accompanying Public Law 97–304, 

which established the current statutory 

deadlines and the warranted-butprecluded finding, states that the 

amendments were ‘‘not intended to 

allow the Secretary to delay 

commencing the rulemaking process for 

any reason other than that the existence 

of pending or imminent proposals to list 

species subject to a greater degree of 

threat would make allocation of 

resources to such a petition [that is, for 

a lower-ranking species] unwise.’’ 

Although that statement appeared to 

refer specifically to the ‘‘to the 

maximum extent practicable’’ limitation 

on the 90-day deadline for making a 

‘‘substantial information’’ finding, that 

finding is made at the point when the 

Service is deciding whether or not to 

commence a status review that will 

determine the degree of threats facing 

the species, and therefore the analysis 

underlying the statement is more 

relevant to the use of the warranted-butprecluded finding, which is made when 

the Service has already determined the 

degree of threats facing the species and 

is deciding whether or not to commence 

a rulemaking. 

In FY 2010, $10,471,000 is the 

amount of money that Congress 

appropriated for the Listing Program 

(that is, the portion of the Listing 

Program funding not related to critical 

habitat designations for species that are 

already listed). Therefore, a proposed 

listing is precluded if pending proposals 

with higher priority will require 

expenditure of at least $10,471,000, and 

expeditious progress is the amount of 

work that can be achieved with 

$10,471,000. Since court orders 

requiring critical habitat work will not 

require use of all of the funds within the 

critical habitat subcap, we used 

$1,114,417 of our critical habitat subcap 

funds in order to work on as many of 

our required petition findings and 

listing determinations as possible. This 

brings the total amount of funds we had 

for listing actions in FY 2010 to 

$11,585,417. 

The $11,585,417 was used to fund 

work in the following categories: 

compliance with court orders and courtapproved settlement agreements 

requiring that petition findings or listing 

determinations be completed by a 

specific date; section 4 (of the Act) 

listing actions with absolute statutory 

deadlines; essential litigation-related, 


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administrative, and listing programmanagement functions; and highpriority listing actions for some of our 

candidate species. For FY 2011, on 

September 29, 2010, Congress passed a 

continuing resolution which provides 

funding at the FY 2010 enacted level. 

Until Congress appropriates funds for 

FY 2011, we will fund listing work 

based on the FY 2010 amount. In 2009, 

the responsibility for listing foreign 

species under the Act was transferred 

from the Division of Scientific 

Authority, International Affairs 

Program, to the Endangered Species 

Program. Therefore, starting in FY 2010, 

we use a portion of our funding to work 

on the actions described above as they 

apply to listing actions for foreign 

species. This has the potential to further 

reduce funding available for domestic 

listing actions. Although there are 

currently no foreign species issues 

included in our high-priority listing 

actions at this time, many actions have 

statutory or court-approved settlement 

deadlines, thus increasing their priority. 

The budget allocations for each specific 

listing action are identified in the 

Service’s FY 2011 Allocation Table (part 

of our administrative record). 

Based on our September 21, 1983, 

guidance for assigning an LPN for each 

candidate species (48 FR 43098), we 

have a significant number of species 

with an LPN of 2. Using this guidance, 

we assign each candidate an LPN of 1 

to 12, depending on the magnitude of 

threats (high vs. moderate to low), 

immediacy of threats (imminent or 

nonimminent), and taxonomic status of 

the species (in order of priority: 

monotypic genus (a species that is the 

sole member of a genus); species; or part 

of a species (subspecies, distinct 

population segment, or significant 

portion of the range)). The lower the 

listing priority number, the higher the 

listing priority (that is, a species with an 

LPN of 1 would have the highest listing 

priority). 

Because of the large number of highpriority species, we have further ranked 

the candidate species with an LPN of 2 

by using the following extinction-risk 

type criteria: International Union for the 

Conservation of Nature and Natural 

Resources (IUCN) Red list status/rank, 

Heritage rank (provided by 

NatureServe), Heritage threat rank 

(provided by NatureServe), and species 

currently with fewer than 50 

individuals, or 4 or fewer populations. 

Those species with the highest IUCN 

rank (critically endangered), the highest 

Heritage rank (G1), the highest Heritage 

threat rank (substantial, imminent 

threats), and currently with fewer than 

50 individuals, or fewer than 4 

populations, originally comprised a 

group of approximately 40 candidate 

species (‘‘Top 40’’). These 40 candidate 

species have had the highest priority to 

receive funding to work on a proposed 

listing determination. As we work on 

proposed and final listing rules for those 

40 candidates, we apply the ranking 

criteria to the next group of candidates 

with an LPN of 2 and 3 to determine the 

next set of highest priority candidate 

species. Finally, proposed rules for 

reclassification of threatened species to 

endangered are lower priority, since as 

listed species, they are already afforded 

the protection of the Act and 

implementing regulations. However, for 

efficiency reasons, we may choose to 

work on a proposed rule to reclassify a 

species to endangered if we can 

combine this with work that is subject 

to a court-determined deadline. 

With our workload so much bigger 

than the amount of funds we have to 

accomplish it, it is important that we be 

as efficient as possible in our listing 

process. Therefore, as we work on 

proposed rules for the highest priority 

species in the next several years, we are 

preparing multi-species proposals when 

appropriate, and these may include 

species with lower priority if they 

overlap geographically or have the same 

threats as a species with an LPN of 2. 

In addition, we take into consideration 

the availability of staff resources when 

we determine which high-priority 

species will receive funding to 

minimize the amount of time and 

resources required to complete each 

listing action. 

We assigned wolverines in the 

contiguous United States an LPN of 6, 

based on our finding that the DPS faces 

nonimminent but high-magnitude 

threats from the primary threat of the 

present or threatened destruction, 

modification, or curtailment of its 

habitat from climate change; and the 

secondary threats associated with 

Factors B, D, and E. These threats are 

expected to affect wolverine 

populations in the future. Under our 

1983 Guidelines, a ‘‘species’’ facing 

nonimminent high-magnitude threats is 

assigned an LPN of 4, 5, or 6, depending 

on its taxonomic status. Work on a 

proposed listing determination for 

wolverines in the contiguous United 

States is precluded by work on higher 

priority candidate species (i.e., species 

with LPN of 5 or less); listing actions 

with absolute statutory, court-ordered, 

or court-approved deadlines; and final 

listing determinations for those species 

that were proposed for listing with 

funds from previous FYs. This work 

includes all the actions listed in the 

tables below under expeditious 

progress. 

As explained above, a determination 

that listing is warranted but precluded 

must also demonstrate that expeditious 

progress is being made to add and 

remove qualified species to and from 

the Lists of Endangered and Threatened 

Wildlife and Plants. As with our 

‘‘precluded’’ finding, the evaluation of 

whether progress in adding qualified 

species to the Lists has been expeditious 

is a function of the resources available 

for listing and the competing demands 

for those funds. (Although we do not 

discuss it in detail here, we are also 

making expeditious progress in 

removing species from the list under the 

Recovery program in light of the 

resource available for delisting, which is 

funded by a separate line item in the 

budget of the Endangered Species 

Program. During FY 2010, we have 

completed two proposed delisting rules 

and two final delisting rules.) Given the 

limited resources available for listing, 

we find that we made expeditious 

progress in FY 2010 in the Listing 

Program and are making expeditious 

progress in FY 2011. This progress 

included preparing and publishing the 

determinations presented in Table 3. 

TABLE 3—FY 2010 AND FY 2011 COMPLETED LISTING ACTIONS

Publication date Title Actions FR Pages 

10/08/2009 ........................... Listing Lepidium papilliferum (Slickspot Peppergrass) 

as a Threatened Species Throughout Its Range.

Final Listing, Threatened ............ 74 FR 52013–52064 

10/27/2009 ........................... 90-day Finding on a Petition To List the American Dipper in the Black Hills of South Dakota as Threatened 

or Endangered.

Notice of 90-day Petition Finding, Not Substantial.74 FR 55177–55180 

10/28/2009 ........................... Status Review of Arctic Grayling (Thymallus arcticus) 

in the Upper Missouri River System.

Notice of Intent to Conduct Status Review.74 FR 55524–55525 


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TABLE 3—FY 2010 AND FY 2011 COMPLETED LISTING ACTIONS—Continued 

Publication date Title Actions FR Pages 

11/03/2009 ........................... Listing the British Columbia Distinct Population Segment of the Queen Charlotte Goshawk Under the 

Act: Proposed rule.

Proposed Listing Threatened ..... 74 FR 56757–56770 

11/03/2009 ........................... Listing the Salmon-Crested Cockatoo as Threatened 

Throughout Its Range with Special Rule.

Proposed Listing Threatened ..... 74 FR 56770–56791 

11/23/2009 ........................... Status Review of Gunnison sage-grouse (Centrocercus 

minimus).

Notice of Intent to Conduct Status Review.74 FR 61100–61102 

12/03/2009 ........................... 12-Month Finding on a Petition to List the Black-tailed 

Prairie Dog as Threatened or Endangered.

Notice of 12-month Petition Finding, Not warranted.74 FR 63343–63366 

12/03/2009 ........................... 90-Day Finding on a Petition to List Sprague’s Pipit as 

Threatened or Endangered.

Notice of 90-day Petition Finding, Substantial.74 FR 63337–63343 

12/15/2009 ........................... 90-Day Finding on Petitions To List 9 Species of Mussels From Texas as Threatened or Endangered With 

Critical Habitat.

Notice of 90-day Petition Finding, Substantial.74 FR 66260–66271 

12/16/2009 ........................... Partial 90-Day Finding on a Petition to List 475 Species in the Southwestern United States as Threatened or Endangered With Critical Habitat.Notice of 90-day Petition Finding, Not Substantial & 

Subtantial.

74 FR 66865–66905 

12/17/2009 ........................... 12-month Finding on a Petition To Change the Final 

Listing of the Distinct Population Segment of the 

Canada Lynx To Include New Mexico.

Notice of 12-month Petition Finding, Warranted but Precluded.74 FR 66937–66950 

01/05/2010 ........................... Listing Foreign Bird Species in Peru & Bolivia as Endangered Throughout Their Range.Proposed Listing, Endangered ... 75 FR 605–649 

01/05/2010 ........................... Listing Six Foreign Birds as Endangered Throughout 

Their Range.

Proposed Listing, Endangered ... 75 FR 286–310 

01/05/2010 ........................... Withdrawal of Proposed Rule to List Cook’s Petrel ....... Proposed rule, Withdrawal ......... 75 FR 310–316 

01/05/2010 ........................... Final Rule to List the Galapagos Petrel & Heinroth’s 

Shearwater as Threatened Throughout Their Ranges.

Final Listing, Threatened ............ 75 FR 235–250 

01/20/2010 ........................... Initiation of Status Review for Agave eggersiana & 

Solanum conocarpum.

Notice of Intent to Conduct Status Review.75 FR 3190–3191 

02/09/2010 ........................... 12-month Finding on a Petition to List the American 

Pika as Threatened or Endangered.

Notice of 12-month Petition Finding, Not Warranted.75 FR 6437–6471 

02/25/2010 ........................... 12-Month Finding on a Petition To List the Sonoran 

Desert Population of the Bald Eagle as a Threatened or Endangered Distinct Population Segment.

Notice of 12-month Petition Finding, Not Warranted.75 FR 8601–8621 

02/25/2010 ........................... Withdrawal of Proposed Rule To List the Southwestern 

Washington/Columbia River Distinct Population Segment of Coastal Cutthroat Trout (Oncorhynchus 

clarki clarki) as Threatened.

Withdrawal of Proposed Rule to 

List.

75 FR 8621–8644 

03/18/2010 ........................... 90-Day Finding on a Petition to List the Berry Cave 

salamander as Endangered.

Notice of 90-day Petition Finding, Substantial.75 FR 13068–13071 

03/23/2010 ........................... 90-Day Finding on a Petition to List the Southern 

Hickorynut Mussel (Obovaria jacksoniana) as Endangered or Threatened.

Notice of 90-day Petition Finding, Not Substantial.75 FR 13717–13720 

03/23/2010 ........................... 90-Day Finding on a Petition to List the Striped Newt 

as Threatened.

Notice of 90-day Petition Finding, Substantial.75 FR 13720–13726 

03/23/2010 ........................... 12-Month Findings for Petitions to List the Greater 

Sage-Grouse (Centrocercus urophasianus) as 

Threatened or Endangered.

Notice of 12-month Petition Finding, Warranted but Precluded.75 FR 13910–14014 

03/31/2010 ........................... 12-Month Finding on a Petition to List the Tucson 

Shovel-Nosed Snake (Chionactis occipitalis klauberi) 

as Threatened or Endangered with Critical Habitat.

Notice of 12-month Petition Finding, Warranted but Precluded.75 FR 16050–16065 

04/05/2010 ........................... 90-Day Finding on a Petition To List Thorne’s 

Hairstreak Butterfly as or Endangered.

Notice of 90-day Petition Finding, Substantial.75 FR 17062–17070 

04/06/2010 ........................... 12-month Finding on a Petition To List the Mountain 

Whitefish in the Big Lost River, Idaho, as Endangered or Threatened.

Notice of 12-month Petition Finding, Not Warranted.75 FR 17352–17363 

04/06/2010 ........................... 90-Day Finding on a Petition to List a Stonefly 

(Isoperla jewetti) & a Mayfly (Fallceon eatoni) as 

Threatened or Endangered with Critical Habitat.

Notice of 90-day Petition Finding, Not Substantial.75 FR 17363–17367 

04/07/2010 ........................... 12-Month Finding on a Petition to Reclassify the Delta 

Smelt From Threatened to Endangered Throughout 

Its Range.

Notice of 12-month Petition Finding, Warranted but Precluded.75 FR 17667–17680 

04/13/2010 ........................... Determination of Endangered Status for 48 Species on 

Kauai & Designation of Critical Habitat.

Final Listing, Endangered ........... 75 FR 18959–19165 

04/15/2010 ........................... Initiation of Status Review of the North American Wolverine in the Contiguous United States.Notice of Initiation of Status Review.75 FR 19591–19592 

04/15/2010 ........................... 12-Month Finding on a Petition to List the Wyoming 

Pocket Gopher as Endangered or Threatened with 

Critical Habitat.

Notice of 12-month Petition Finding, Not Warranted.75 FR 19592–19607 


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TABLE 3—FY 2010 AND FY 2011 COMPLETED LISTING ACTIONS—Continued 

Publication date Title Actions FR Pages 

04/16/2010 ........................... 90-Day Finding on a Petition to List a Distinct Population Segment of the Fisher in Its United States 

Northern Rocky Mountain Range as Endangered or 

Threatened with Critical Habitat.

Notice of 90-day Petition Finding, Substantial.75 FR 19925–19935 

04/20/2010 ........................... Initiation of Status Review for Sacramento splittail 

(Pogonichthys macrolepidotus).

Notice of Initiation of Status Review.75 FR 20547–20548 

04/26/2010 ........................... 90-Day Finding on a Petition to List the Harlequin Butterfly as Endangered.Notice of 90-day Petition Finding, Substantial.75 FR 21568–21571 

04/27/2010 ........................... 12-Month Finding on a Petition to List Susan’s Pursemaking Caddisfly (Ochrotrichia susanae) as Threatened or Endangered.Notice of 12-month Petition Finding, Not Warranted.75 FR 22012–22025 

04/27/2010 ........................... 90-day Finding on a Petition to List the Mohave 

Ground Squirrel as Endangered with Critical Habitat.

Notice of 90-day Petition Finding, Substantial.75 FR 22063–22070 

05/04/2010 ........................... 90-Day Finding on a Petition to List Hermes Copper 

Butterfly as Threatened or Endangered.

Notice of 90-day Petition Finding, Substantial.75 FR 23654–23663 

6/1/2010 ............................... 90-Day Finding on a Petition To List Castanea pumila 

var. ozarkensis.

Notice of 90-day Petition Finding, Substantial.75 FR 30313–30318 

6/1/2010 ............................... 12-month Finding on a Petition to List the White-tailed 

Prairie Dog as Endangered or Threatened.

Notice of 12-month Petition Finding, Not warranted.75 FR 30338–30363 

6/9/2010 ............................... 90–Day Finding on a Petition To List van Rossem’s 

Gull-billed Tern as Endangered or Threatened.

Notice of 90-day Petition Finding, Substantial.75 FR 32728–32734 

6/16/2010 ............................. 90-Day Finding on Five Petitions to List Seven Species 

of Hawaiian Yellow-faced Bees as Endangered.

Notice of 90-day Petition Finding, Substantial.75 FR 34077–34088 

6/22/2010 ............................. 12-Month Finding on a Petition to List the Least Chub 

as Threatened or Endangered.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 35398–35424 

6/23/2010 ............................. 90-Day Finding on a Petition to List the Honduran Emerald Hummingbird as Endangered.Notice of 90-day Petition Finding, Substantial.75 FR 35746–35751 

6/23/2010 ............................. Listing Ipomopsis polyantha (Pagosa Skyrocket) as 

Endangered Throughout Its Range, and Listing 

Penstemon debilis (Parachute Beardtongue) and 

Phacelia submutica (DeBeque Phacelia) as Threatened Throughout Their Range.

Proposed Listing, Endangered; 

Proposed Listing, Threatened.

75 FR 35721–35746 

6/24/2010 ............................. Listing the Flying Earwig Hawaiian Damselfly and Pacific Hawaiian Damselfly As Endangered Throughout 

Their Ranges.

Final Listing, Endangered ........... 75 FR 35990–36012 

6/24/2010 ............................. Listing the Cumberland Darter, Rush Darter, 

Yellowcheek Darter, Chucky Madtom, and Laurel 

Dace as Endangered Throughout Their Ranges.

Proposed Listing, Endangered ... 75 FR 36035–36057 

6/29/2010 ............................. Listing the Mountain Plover as Threatened ................... Reinstatement of Proposed Listing, Threatened.75 FR 37353–37358 

7/20/2010 ............................. 90-Day Finding on a Petition to List Pinus albicaulis 

(Whitebark Pine) as Endangered or Threatened with 

Critical Habitat.

Notice of 90-day Petition Finding, Substantial.75 FR 42033–42040 

7/20/2010 ............................. 12-Month Finding on a Petition to List the Amargosa 

Toad as Threatened or Endangered.

Notice of 12-month Petition Finding, Not warranted.75 FR 42040–42054 

7/20/2010 ............................. 90–Day Finding on a Petition to List the Giant Palouse 

Earthworm (Driloleirus americanus) as Threatened 

or Endangered.

Notice of 90-day Petition Finding, Substantial.75 FR 42059–42066 

7/27/2010 ............................. Determination on Listing the Black-Breasted Puffleg as 

Endangered Throughout its Range; Final Rule.

Final Listing, Endangered ........... 75 FR 43844–43853 

7/27/2010 ............................. Final Rule to List the Medium Tree-Finch 

(Camarhynchus pauper) as Endangered Throughout 

Its Range.

Final Listing, Endangered ........... 75 FR 43853–43864 

8/3/2010 ............................... Determination of Threatened Status for Five Penguin 

Species.

Final Listing, Threatened ............ 75 FR 45497–45527 

8/4/2010 ............................... 90-Day Finding on a Petition To List the Mexican Gray 

Wolf as an Endangered Subspecies With Critical 

Habitat.

Notice of 90-day Petition Finding, Substantial.75 FR 46894–46898 

8/10/2010 ............................. 90-Day Finding on a Petition to List Arctostaphylos 

franciscana as Endangered with Critical Habitat.

Notice of 90-day Petition Finding, Substantial.75 FR 48294–48298 

8/17/2010 ............................. Listing Three Foreign Bird Species from Latin America 

and the Caribbean as Endangered Throughout Their 

Range.

Final Listing, Endangered ........... 75 FR 50813–50842 

8/17/2010 ............................. 90-Day Finding on a Petition to List Brian Head 

Mountainsnail as Endangered or Threatened with 

Critical Habitat.

Notice of 90-day Petition Finding, Not substantial.75 FR 50739–50742 

8/24/2010 ............................. 90-Day Finding on a Petition to List the Oklahoma 

Grass Pink Orchid as Endangered or Threatened.

Notice of 90-day Petition Finding, Substantial.75 FR 51969–51974 

9/1/2010 ............................... 12-Month Finding on a Petition to List the White-Sided 

Jackrabbit as Threatened or Endangered.

Notice of 12-month Petition Finding, Not warranted.75 FR 53615–53629 

9/8/2010 ............................... Proposed Rule To List the Ozark Hellbender Salamander as Endangered.Proposed Listing, Endangered ... 75 FR 54561–54579 


jlentini on DSKJ8SOYB1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 239 / Tuesday, December 14, 2010 / Proposed Rules 78059 

TABLE 3—FY 2010 AND FY 2011 COMPLETED LISTING ACTIONS—Continued 

Publication date Title Actions FR Pages 

9/8/2010 ............................... Revised 12-Month Finding to List the Upper Missouri 

River Distinct Population Segment of Arctic Grayling 

as Endangered or Threatened.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 54707–54753 

9/9/2010 ............................... 12-Month Finding on a Petition to List the Jemez 

Mountains Salamander (Plethodon neomexicanus) 

as Endangered or Threatened with Critical Habitat.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 54822–54845 

9/15/2010 ............................. 12-Month Finding on a Petition to List Sprague’s Pipit 

as Endangered or Threatened Throughout Its Range.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 56028–56050 

9/22/2010 ............................. 12-Month Finding on a Petition to List Agave 

eggersiana (no common name) as Endangered.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 57720–57734 

9/28/2010 ............................. Determination of Endangered Status for the African 

Penguin.

Final Listing, Endangered ........... 75 FR 59645–59656 

9/28/2010 ............................. Determination for the Gunnison Sage-grouse as a 

Threatened or Endangered Species.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 59803–59863 

9/30/2010 ............................. 12-Month Finding on a Petition to List the Pygmy Rabbit as Endangered or Threatened.Notice of 12-month Petition Finding, Not warranted.75 FR 60515–60561 

10/6/2010 ............................. Endangered Status for the Altamaha Spinymussel and 

Designation of Critical Habitat.

Proposed Listing, Endangered ... 75 FR 61664–61690 

10/7/2010 ............................. 12-month Finding on a Petition to list the Sacramento 

Splittail as Endangered or Threatened.

Notice of 12-month Petition Finding, Not warranted.75 FR 62070–62095 

10/28/2010 ........................... Endangered Status and Designation of Critical Habitat 

for Spikedace and Loach Minnow.

Proposed Listing Endangered 

(uplisting).

75 FR 66481–66552 

11/2/2010 ............................. 90-Day Finding on a Petition to List the Bay Springs 

Salamander as Endangered.

Notice of 90-day Petition Finding, Not substantial.75 FR 67341–67343 

11/2/2010 ............................. Determination of Endangered Status for the Georgia 

Pigtoe Mussel, Interrupted Rocksnail, and Rough 

Hornsnail and Designation of Critical Habitat.

Final Listing, Endangered ........... 75 FR 67511–67550 

11/2/2010 ............................. Listing the Rayed Bean and Snuffbox as Endangered Proposed Listing, Endangered ... 75 FR 67551–67583 

11/4/2010 ............................. 12-Month Finding on a Petition to List Cirsium wrightii 

(Wright’s Marsh Thistle) as Endangered or Threatened.

Notice of 12-month Petition Finding, Warranted but precluded.75 FR 67925–67944 

Our expeditious progress also 

includes work on listing actions that we 

funded in FY 2010 and FY 2011 but 

have not yet been completed to date. 

These actions are listed below. Actions 

in the top section of the table are being 

conducted under a deadline set by a 

court. Actions in the middle section of 

the table are being conducted to meet 

statutory timelines, that is, timelines 

required under the Act. Actions in the 

bottom section of the table are highpriority listing actions. These actions 

include work primarily on species with 

an LPN of 2, and, as discussed above, 

selection of these species is partially 

based on available staff resources, and 

when appropriate, include species with 

a lower priority if they overlap 

geographically or have the same threats 

as the species with the high priority. 

Including these species together in the 

same proposed rule results in 

considerable savings in time and 

funding, as compared to preparing 

separate proposed rules for each of them 

in the future. 

TABLE 4—ACTIONS FUNDED IN FY 2010 AND FY 2011 BUT NOT YET COMPLETED

Species Action 

Actions Subject to Court Order/Settlement Agreement: 

6 Birds from Eurasia ....................................................................................................................................... Final listing determination. 

Flat-tailed horned lizard .................................................................................................................................. Final listing determination. 

Mountain plover 4 ............................................................................................................................................ Final listing determination. 

6 Birds from Peru ........................................................................................................................................... Proposed listing determination. 

Sacramento splittail ........................................................................................................................................ 12-month petition finding. 

Pacific walrus .................................................................................................................................................. 12-month petition finding. 

Wolverine ........................................................................................................................................................ 12-month petition finding. 

Solanum conocarpum ..................................................................................................................................... 12-month petition finding. 

Desert tortoise—Sonoran population ............................................................................................................. 12-month petition finding. 

Thorne’s Hairstreak butterfly 3 ........................................................................................................................ 12-month petition finding. 

Hermes copper butterfly 3 ............................................................................................................................... 12-month petition finding. 

Utah prairie dog (uplisting) ............................................................................................................................. 90-day petition finding. 

Actions with Statutory Deadlines: 

Casey’s june beetle ........................................................................................................................................ Final listing determination. 

Georgia pigtoe, interrupted rocksnail, and rough hornsnail ........................................................................... Final listing determination. 

7 Bird species from Brazil .............................................................................................................................. Final listing determination. 

Southern rockhopper penguin—Campbell Plateau population ...................................................................... Final listing determination. 

5 Bird species from Colombia and Ecuador .................................................................................................. Final listing determination. 

Queen Charlotte goshawk .............................................................................................................................. Final listing determination. 

5 species southeast fish (Cumberland darter, rush darter, yellowcheek darter, chucky madtom, and laurel 

dace).

Final listing determination. 

Salmon crested cockatoo ............................................................................................................................... Proposed listing determination. 


jlentini on DSKJ8SOYB1PROD with PROPOSALS2
78060 Federal Register / Vol. 75, No. 239 / Tuesday, December 14, 2010 / Proposed Rules 

TABLE 4—ACTIONS FUNDED IN FY 2010 AND FY 2011 BUT NOT YET COMPLETED—Continued 

Species Action 

CA golden trout .............................................................................................................................................. 12-month petition finding. 

Black-footed albatross .................................................................................................................................... 12-month petition finding. 

Mount Charleston blue butterfly ..................................................................................................................... 12-month petition finding. 

Mojave fringe-toed lizard 1 .............................................................................................................................. 12-month petition finding. 

Kokanee—Lake Sammamish population 1 ..................................................................................................... 12-month petition finding.

Cactus ferruginous pygmy-owl 1 ..................................................................................................................... 12-month petition finding. 

Northern leopard frog ..................................................................................................................................... 12-month petition finding. 

Tehachapi slender salamander ...................................................................................................................... 12-month petition finding. 

Coqui Llanero ................................................................................................................................................. 12-month petition finding. 

Dusky tree vole ............................................................................................................................................... 12-month petition finding. 

3 MT invertebrates (mist forestfly (Lednia tumana), Oreohelix sp.3, Oreohelix sp. 31) from 206 species 

petition.

12-month petition finding. 

5 UT plants (Astragalus hamiltonii, Eriogonum soredium, Lepidium ostleri, Penstemon flowersii, Trifolium 

friscanum) from 206 species petition.

12-month petition finding. 

2 CO plants (Astragalus microcymbus, Astragalus schmolliae) from 206 species petition .......................... 12-month petition finding. 

5 WY plants (Abronia ammophila, Agrostis rossiae, Astragalus proimanthus, Boechere (Arabis) pusilla, 

Penstemon gibbensii) from 206 species petition.

12-month petition finding. 

Leatherside chub (from 206 species petition) ................................................................................................ 12-month petition finding. 

Frigid ambersnail (from 206 species petition) ................................................................................................ 12-month petition finding. 

Gopher tortoise—eastern population ............................................................................................................. 12-month petition finding. 

Wrights marsh thistle ...................................................................................................................................... 12-month petition finding. 

67 of 475 southwest species .......................................................................................................................... 12-month petition finding. 

Grand Canyon scorpion (from 475 species petition) ..................................................................................... 12-month petition finding. 

Anacroneuria wipukupa (a stonefly from 475 species petition) ..................................................................... 12-month petition finding. 

Rattlesnake-master borer moth (from 475 species petition) .......................................................................... 12-month petition finding. 

3 Texas moths (Ursia furtiva, Sphingicampa blanchardi, Agapema galbina) (from 475 species petition) ... 12-month petition finding. 

2 Texas shiners (Cyprinella sp., Cyprinella lepida) (from 475 species petition) ........................................... 12-month petition finding. 

3 South Arizona plants (Erigeron piscaticus, Astragalus hypoxylus, Amoreuxia gonzalezii) (from 475 species petition).12-month petition finding. 

5 Central Texas mussel species (3 from 475 species petition) ..................................................................... 12-month petition finding. 

14 parrots (foreign species) ........................................................................................................................... 12-month petition finding. 

Berry Cave salamander 1 ............................................................................................................................... 12-month petition finding. 

Striped Newt 1 ................................................................................................................................................. 12-month petition finding. 

Fisher—Northern Rocky Mountain Range 1 ................................................................................................... 12-month petition finding. 

Mohave Ground Squirrel 1 .............................................................................................................................. 12-month petition finding. 

Puerto Rico Harlequin Butterfly ...................................................................................................................... 12-month petition finding. 

Western gull-billed tern ................................................................................................................................... 12-month petition finding. 

Ozark chinquapin (Castanea pumila var. ozarkensis) ................................................................................... 12-month petition finding. 

HI yellow-faced bees ...................................................................................................................................... 12-month petition finding. 

Giant Palouse earthworm ............................................................................................................................... 12-month petition finding. 

Whitebark pine ................................................................................................................................................ 12-month petition finding. 

OK grass pink (Calopogon oklahomensis) 1 .................................................................................................. 12-month petition finding. 

Southeastern pop snowy plover & wintering pop. of piping plover 1 ............................................................. 90-day petition finding. 

Eagle Lake trout 1 ........................................................................................................................................... 90-day petition finding. 

Smooth-billed ani 1 .......................................................................................................................................... 90-day petition finding. 

Bay Springs salamander 1 .............................................................................................................................. 90-day petition finding. 

32 species of snails and slugs 1 ..................................................................................................................... 90-day petition finding. 

42 snail species (Nevada & Utah) ................................................................................................................. 90-day petition finding. 

Red knot roselaari subspecies ....................................................................................................................... 90-day petition finding. 

Peary caribou ................................................................................................................................................. 90-day petition finding. 

Plains bison .................................................................................................................................................... 90-day petition finding. 

Spring Mountains checkerspot butterfly ......................................................................................................... 90-day petition finding. 

Spring pygmy sunfish ..................................................................................................................................... 90-day petition finding. 

Bay skipper ..................................................................................................................................................... 90-day petition finding. 

Unsilvered fritillary .......................................................................................................................................... 90-day petition finding. 

Texas kangaroo rat ........................................................................................................................................ 90-day petition finding. 

Spot-tailed earless lizard ................................................................................................................................ 90-day petition finding. 

Eastern small-footed bat ................................................................................................................................ 90-day petition finding. 

Northern long-eared bat ................................................................................................................................. 90-day petition finding. 

Prairie chub .................................................................................................................................................... 90-day petition finding. 

10 species of Great Basin butterfly ................................................................................................................ 90-day petition finding. 

6 sand dune (scarab) beetles ........................................................................................................................ 90-day petition finding. 

Golden-winged warbler ................................................................................................................................... 90-day petition finding. 

Sand-verbena moth ........................................................................................................................................ 90-day petition finding. 

404 Southeast species ................................................................................................................................... 90-day petition finding. 

Franklin’s bumble bee 4 .................................................................................................................................. 90-day petition finding. 

2 Idaho snowflies (straight snowfly & Idaho snowfly) 4 .................................................................................. 90-day petition finding. 

American eel 4 ................................................................................................................................................ 90-day petition finding. 

Gila monster (Utah population) 4 .................................................................................................................... 90-day petition finding. 

Arapahoe snowfly 4 ......................................................................................................................................... 90-day petition finding. 

Leona’s little blue 4 ......................................................................................................................................... 90-day petition finding. 

Aztec gilia 5 ..................................................................................................................................................... 90-day petition finding. 


jlentini on DSKJ8SOYB1PROD with PROPOSALS2
Federal Register / Vol. 75, No. 239 / Tuesday, December 14, 2010 / Proposed Rules 78061 

TABLE 4—ACTIONS FUNDED IN FY 2010 AND FY 2011 BUT NOT YET COMPLETED—Continued 

Species Action 

White-tailed ptarmigan 5 ................................................................................................................................. 90-day petition finding. 

San Bernardino flying squirrel 5 ...................................................................................................................... 90-day petition finding. 

Bicknell’s thrush 5 ........................................................................................................................................... 90-day petition finding. 

Coleman’s coral-root (Hexalectris colemanii) 5 .............................................................................................. 90-day petition finding. 

Sonoran talussnail 5 ........................................................................................................................................ 90-day petition finding. 

2 AZ Sky Island plants (Graptopetalum bartrami & Pectis imberbis) 5 .......................................................... 90-day petition finding. 

I’iwi 5 ................................................................................................................................................................ 90-day petition finding. 

High-Priority Listing Actions 3: 

19 Oahu candidate species 2 (16 plants, 3 damselflies) (15 with LPN = 2, 3 with LPN = 3, 1 with LPN = 

9).

Proposed listing. 

19 Maui-Nui candidate species 2 (16 plants, 3 tree snails) (14 with LPN = 2, 2 with LPN = 3, 3 with LPN 

= 8).

Proposed listing. 

Dune sagebrush lizard (formerly Sand dune lizard) 3 (LPN = 2) ................................................................... Proposed listing. 

2 Arizona springsnails 2 (Pyrgulopsis bernadina (LPN = 2), Pyrgulopsis trivialis (LPN = 2)) ....................... Proposed listing. 

New Mexico springsnail 2 (Pyrgulopsis chupaderae (LPN = 2) ..................................................................... Proposed listing. 

2 mussels 2 (rayed bean (LPN = 2), snuffbox No LPN) ................................................................................. Proposed listing. 

2 mussels 2 (sheepnose (LPN = 2), spectaclecase (LPN = 4)) ..................................................................... Proposed listing. 

Altamaha spinymussel 2 (LPN = 2) ................................................................................................................ Proposed listing. 

8 southeast mussels (southern kidneyshell (LPN = 2), round ebonyshell (LPN = 2), Alabama pearlshell 

(LPN = 2), southern sandshell (LPN = 5), fuzzy pigtoe (LPN = 5), Choctaw bean (LPN = 5), narrow 

pigtoe (LPN = 5), and tapered pigtoe (LPN = 11)).

Proposed listing. 

Umtanum buckwheat (LPN = 2) 4 ................................................................................................................... Proposed listing. 

Grotto sculpin (LPN = 2) 4 .............................................................................................................................. Proposed listing. 

2 Arkansas mussels (Neosho mucket (LPN = 2) & Rabbitsfoot (LPN = 9)) 4 ............................................... Proposed listing. 

Diamond darter (LPN = 2) 4 ............................................................................................................................ Proposed listing. 

Gunnison sage-grouse (LPN = 2) 4 ................................................................................................................ Proposed listing. 

Miami blue (LPN = 3) 3 ................................................................................................................................... Proposed listing. 

4 Texas salamanders (Austin blind salamander (LPN = 2), Salado salamander (LPN = 2), Georgetown 

salamander (LPN = 8), Jollyville Plateau (LPN = 8)) 3.

Proposed listing. 

5 SW aquatics (Gonzales Spring Snail (LPN = 2), Diamond Y springsnail (LPN = 2), Phantom 

springsnail (LPN = 2), Phantom Cave snail (LPN = 2), Diminutive amphipod (LPN = 2)) 3.

Proposed listing. 

2 Texas plants (Texas golden gladecress (Leavenworthia texana) (LPN = 2), Neches River rose-mallow 

(Hibiscus dasycalyx) (LPN = 2)) 3.

Proposed listing. 

FL bonneted bat (LPN = 2) 3 .......................................................................................................................... Proposed listing. 

Kittlitz’s murrelet (LPN = 2) 5 .......................................................................................................................... Proposed listing. 

Umtanum buckwheat (LPN = 2) 3 ................................................................................................................... Proposed listing. 

21 Big Island (HI) species 5 (includes 8 candidate species—5 plants & 3 animals; 4 with LPN = 2, 1 with 

LPN = 3, 1 with LPN = 4, 2 with LPN = 8).

Proposed listing. 

Oregon spotted frog (LPN = 2) 5 .................................................................................................................... Proposed listing. 

2 TN River mussels (fluted kidneyshell (LPN = 2), slabside pearlymussel (LPN = 2) 5 ............................... Proposed listing. 

Jemez Mountain salamander (LPN = 2) 5 ...................................................................................................... Proposed listing. 

1Funds for listing actions for these species were provided in previous FYs. 

2Although funds for these high-priority listing actions were provided in FY 2008 or 2009, due to the complexity of these actions and competing 

priorities, these actions are still being developed. 3Partially funded with FY 2010 funds and FY 2011 funds. 

4Funded with FY 2010 funds. 

5Funded with FY 2011 funds. 

We have endeavored to make our 

listing actions as efficient and timely as 

possible, given the requirements of the 

relevant law and regulations, and 

constraints relating to workload and 

personnel. We are continually 

considering ways to streamline 

processes or achieve economies of scale, 

such as by batching related actions 

together. Given our limited budget for 

implementing section 4 of the Act, these 

actions described above collectively 

constitute expeditious progress. 

The North American wolverine in the 

contiguous United States will be added 

to the list of candidate species upon 

publication of this 12-month finding. 

We will continue to evaluate this 

species as new information becomes 

available. Continuing review will 

determine if a change in status is 

warranted, including the need to make 

prompt use of emergency listing 

procedures. 

We intend that any proposed listing 

determination for the North American 

wolverine in the contiguous United 

States will be as accurate as possible. 

Therefore, we will continue to accept 

additional information and comments 

from all concerned governmental 

agencies, the scientific community, 

industry, or any other interested party 

concerning this finding. 

References Cited 

A complete list of all references cited 

is available upon request from the 

Supervisor at the U.S. Fish and Wildlife 

Service, Montana Field Office (see 

ADDRESSES). 

Author 

The primary authors of this notice are 

the staff members of the Montana Field 

Office (see ADDRESSES). 

Authority 

The authority for this action is section 

4 of the Endangered Species Act of 

1973, as amended (16 U.S.C. 1531 et 

seq.). 

Dated: November 19, 2010. 

Paul R. Schmidt, 

Acting Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. 2010–30573 Filed 12–13–10; 8:45 am] 

BILLING CODE 4310–55–P 


jlentini on DSKJ8SOYB1PROD with PROPOSALS2