2008 Federal Register, 73 FR 12929; Centralized Library: U.S. Fish and Wildlife Service

[Federal Register: March 11, 2008 (Volume 73, Number 48)]
[Proposed Rules]
[Page 12929-12941]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11mr08-26]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R6-2008-0029; 1111 FY07 MO-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.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list as an endangered or threatened
species under the Endangered Species Act of 1973, as amended (Act), the
population of the North American wolverine (Gulo gulo luscus) that
occurs in the contiguous United States. After a review of the best
available scientific and commercial information, we have determined
that the population of North American wolverine occurring in the
contiguous United States does not constitute a listable entity under
the Act. Therefore, we find that the petition to list the North
American wolverine (Gulo gulo luscus) that occurs in the contiguous
United States is not warranted for listing. The Service will continue
to seek new information on the taxonomy, biology, ecology, and status
of the North American wolverine and we will continue to support
cooperative conservation of wolverines in the contiguous United States.

DATES: This finding was made on March 11, 2008.

ADDRESSES: This finding is available on the Internet at http://
www.regulations.gov. Supporting documentation we used to prepare this
finding is available for public inspection, by appointment, during
normal business hours at the U.S. Fish and Wildlife Service, Montana
Field Office, 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 street address.

FOR FURTHER INFORMATION CONTACT: Mark Wilson, Field Supervisor, U.S.
Fish and Wildlife Service, Montana Field Office (see ADDRESSES). 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 containing substantial scientific and commercial
information that listing may be warranted, we make a finding within 12
months of the date of receipt of the petition on whether the petitioned
action is: (a) Not warranted, (b) warranted, or (c) warranted, but that
immediate proposal of a regulation implementing the petitioned action
is precluded by other pending proposals to determine whether species
are threatened or endangered, and expeditious progress is being made to
add or remove qualified species from the 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

We received a petition dated August 3, 1994, from the Predator
Project (now named the Predator Conservation Alliance) and Biodiversity
Legal Foundation to list the North American wolverine in the contiguous
United States as a threatened or endangered species under the Act and
to designate critical habitat concurrent with listing. On April 19,
1995, we published a finding (60 FR 19567) that the petition did not
provide substantial scientific or commercial information indicating
that listing the North American wolverine in the contiguous United
States may be warranted. We did not make a determination as to whether
the contiguous United States population of the North American wolverine
constituted a distinct population segment or other listable entity.
On July 14, 2000, we received another 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
North American wolverine within the contiguous United States as a
threatened or endangered species under the Act and to designate
critical habitat for the species concurrent with the listing.
On October 21, 2003, we published a 90-day finding that the
petition to list the North American wolverine in the contiguous United
States did not present substantial scientific and commercial
information indicating that listing as threatened or endangered may be
warranted (68 FR 60112). We did not determine whether the contiguous
United States population of the North American wolverine constituted a
distinct population segment (or other listable entity), because
sufficient information was not available at the time.
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

[[Page 12930]]

petition finding was in error and ordered us to make a 12-month finding
for the wolverine (Defenders of Wildlife et al. v. Norton and Hogan
(9:05cv99 DWM; D. MT)). On April 6, 2007, the Court approved an
unopposed motion to extend the deadline for this 12-month finding to
February 28, 2008, so that we would be able to use information
published in the September 2007 edition of the Journal of Wildlife
Management containing a special section on North American wolverine
biology. On June 5, 2007, we published a notice initiating a status
review for the wolverine (72 FR 31048).

Species Biology

The currently accepted taxonomy classifies wolverines worldwide as
a single species, Gulo gulo. The wolverine has a holarctic
distribution. Old and New World wolverines are divided into separate
Old World and New World subspecies. Wolverines of Eurasia (Old World)
comprise the subspecies G. g. gulo. Wolverines in the contiguous United
States are a part of the New World or North American (United States and
Canada) subspecies, G. g. luscus (Kurten and Rausch 1959, p. 19;
Pasitschniak-Arts and Lariviere 1995, p. 1). The two subspecies differ
in minor aspects of skull morphology (Kurten and Rausch 1959, p. 19),
but significant differences in ecology, behavior, demography, or
natural history do not appear to exist. Most authors, when discussing
these aspects of wolverine biology, refer to New and Old World
wolverines interchangeably (e.g., Pasitschniak-Arts and Lariviere 1995,
entire). We consider the Old and New World subspecies to be similar and
reliable enough to refer to information on Old World wolverines (G. g.
gulo) as a surrogate for the North American wolverine in this finding
when such information is not available specifically for the North
American subspecies.
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).
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 consume large ungulate carrion when available. The most
important food items in wolverine diets are large ungulate species,
followed by small animals such as beaver, marmots, ground squirrels,
rabbits, hares, porcupine, voles, ground nesting birds, and insects
(Banci 1994, p. 112; Pasitschniak-Arts and Lariviere 1995, pp. 498-
499). The large ungulates in wolverine diets are assumed to be the
result of scavenging, although wolverines are able to occasionally kill
large ungulates in deep snow conditions when ungulate mobility is
impaired (Pasitschniak-Arts and Lariviere 1995, pp. 498-499). Large
ungulates comprise a larger proportion of the diet in winter than in
snow-free seasons (Banci 1994, Table 5). The availability of large
ungulate herds is of paramount importance for wolverines and the
availability of large mammals underlies the wolverine's distribution,
survival, and reproductive success (Banci 1994, p. 111).
Wolverines have delayed onset of reproduction in females and small
litter sizes. Studies of wolverine carcasses from trapper harvest have
provided some useful data on reproductive parameters (Rausch and
Pearson 1972, pp. 253-267; Liskop et al. 1981, pp. 472-476; Banci and
Harestad 1988, pp. 266-268). These carcass studies indicate that a
large number of female wolverines (40 percent) are apparently capable
of giving birth at 2 years old, become pregnant most years, and produce
average litter sizes of approximately 3.4 kits. However, carcass
studies are subject to overestimating frequency of reproduction and the
number of kits per litter, and underestimating the age at first
reproduction because embryos are often resorbed by females that are
energetically unable to complete pregnancy (Persson et al. 2006, p. 75;
Inman et al. 2007c, p. 70). These aborted pregnancies result in corpora
lutea (uterine scarring) in the female reproductive tract, leading to
the erroneous conclusion that a female had reproduced at an early age
and that litter sizes are relatively large.
Field studies using radio telemetry are better able to determine
the actual age at first reproduction and the actual number of kits
successfully raised to weaning. Based on these studies, average age at
first reproduction is likely more than 3 years (Inman et al. 2007c, p.
70). Pregnant females commonly resorb or spontaneously abort litters
when food availability is so low as to prevent successful completion of
pregnancy or lactation to the time of weaning (Magoun 1985, pp. 30-31;
Copeland 1996, p. 43; Persson et al. 2006, p. 77; Inman et al. 2007c,
p. 70). Supplemental feeding of females increases reproductive
potential (Persson 2005, p. 1456) and success at raising kits to the
time of weaning, and indicates that food availability is likely to be a
limiting factor for wolverine populations. 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 for this study was 3.4 years (rather than 2 years for the
carcass studies above) (Persson et al. 2006, pp. 76-77). From these
studies, we conclude that, by age three, nearly all female wolverines
become pregnant every year, but energetic constraints resulting from
low food availability result in loss of pregnancy about every other
year. It is likely that, in many places in the range of wolverines in
the lower 48 States, it takes 2 years of foraging for a female to store
enough energy to successfully reproduce (Persson 2005, p. 1456; Inman
et al. 2007c, Table 3).
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 between February and April and contain 1 to
5 kits, with an average in North America of between 1 and 2 kits
(rather than 3.4 kits, as indicated by carcass studies) (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).
Several aspects related to reproductive denning are significant to
wolverine reproductive success (Banci 1994, p. 110; Magoun and Copeland
1998, p. 1319; Inman et al. 2007c, p. 71). Female wolverines use two
kinds of dens for reproduction. Females use natal (birthing) dens to
give birth and raise kits early postpartum, and in some cases females
may raise kits to weaning in the natal den. However, in most situations
prior to weaning, females may move kits to one or multiple alternative
den sites, which are referred to as maternal dens. The female then
raises her kits to weaning in the maternal den. The movement of kits
from natal to maternal dens may be a response by the female to den
disturbance, better food

[[Page 12931]]

availability in the new location, predation risk, or deteriorating den
conditions in the natal den (Magoun and Copeland 1998, pp. 1316-1319).
Female wolverines use natal 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, presumably 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). 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
that 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).
Dens (natal and maternal) are typically used from early February
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 depending on whether or not the female wolverine perceives the
need to move her kits (Magoun and Copeland 1998, pp. 1316-1317).
Females may use multiple secondary (maternal) dens (Pulliainen 1968, p.
343; Myrberget 1968, p. 115), or 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 (snow melt), the maturation of offspring,
disturbance, and geographic location (Myrberget 1968, p. 115; Magoun
1985, p. 73). Post-weaning dens are called rendezvous sites. These dens
may be used through early July. Females leave their kits at rendezvous
sites while foraging, and return periodically to provide food for the
kits. These sites are characterized by natural (unexcavated) cavities
formed by large boulders, downed logs (avalanche debris), and snow
(Inman et al. 2007c, pp. 55-56).

Habitat and Home Range

In North America, wolverines occur within a wide variety of arctic,
sub-arctic and alpine habitats, primarily boreal forests, tundra, and
western mountains throughout Alaska and Canada; however, the southern
portion of their range extends into the contiguous United States,
including Washington, Idaho, Montana, and Wyoming (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). In the contiguous United
States, wolverines are restricted to high-elevation habitats in the
Rocky Mountains and North Cascades containing the arctic and sub-arctic
conditions they require.
Home ranges of wolverines are large, but vary greatly depending on
availability of food, gender, age, and differences in habitat. 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). 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). Home ranges of adult wolverines are
approximately 100 square kilometers (km\2\) to over 900 km\2\ (38.5
square miles (mi\2\) to 348 mi\2\) (Banci 1994, p. 117). Average home
ranges of resident adult females in central Idaho are 384 km\2\ (148
mi\2\), and average home ranges of resident adult males are 1,522 km\2\
(588 mi\2\) (Copeland 1996, p. 50). Wolverines in Glacier National Park
have average male home ranges of 496 km\2\ (193 mi\2\) and female home
ranges of 141 km\2\ (55 mi\2\) (Copeland and Yates 2006, p. 25).
Wolverines in the Greater Yellowstone Area have average adult male home
ranges of 797 km\2\ (311 mi\2\) and average adult female home ranges of
329 km\2\ (128 mi\2\) (Inman et al. 2007a, p. 4). Home ranges for
carnivores of similar body size are smaller than wolverine home ranges
at their southern range terminus. Canada lynx in the United States
Rocky Mountains average 122 km\2\ (47 mi\2\) (Aubry et al. 2000, pp.
383-384), and coyote home ranges extend from 2.5 to 15 km\2\ (1 to 5.8
mi\2\) (Chronert 2007, p. 2).
Wolverine home ranges at the southern terminus of the current range
are large for mammals of the size of wolverines, and may indicate that
wolverines have high energetic requirements and at the same time occupy
relatively unproductive niches (Inman et al. 2007a, p. 11). In
addition, wolverines naturally occur in low densities that average
about one wolverine per 150 km\2\ (58 mi\2\) (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).

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 western 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 evidence exists to show
that wolverine pelts attributed to Quebec or Labrador actually came
from that region; possibly animals were trapped elsewhere and the pelts
were 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 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 elevations in mountains (Slough 2007,
pp. 77-78). In Canada, 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

[[Page 12932]]

occurred concurrently with a reduction in wolverine records for the
Great Lakes region in the lower 48 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 wolverine populations in southern Ontario, because snow
conditions necessary to support wolverines do not currently exist in
the Great Lakes region of the lower 48 States, and are marginal in
southern Ontario (Aubry et al. 2007, p. 2154). 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 where
habitat and climate conditions are favorable (COSEWIC 2003, pp. 13-21;
Aubry et al. 2007, pp. 2152-2155; Slough 2007, p. 79). Throughout this
area, wolverines are managed by regulated harvest at the Province and
State level. Population estimates for Canada and Alaska are approximate
because no wolverine surveys have taken place at the State or national
scale. However, the population in western Canada includes an estimated
15,089 to 18,967 individuals, based on population densities and
occupied area (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.

Wolverine Status in the Contiguous United States

The delineation of the historical and present distribution of
wolverine is inherently difficult for several reasons. Wolverines tend
to live in remote and inhospitable places away from human populations.
Wolverines naturally occur at low 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 (Aubry et al. 2007, p. 2147), making it difficult to distinguish
with confidence between occurrence records that represent established
populations and those that represent short-term occupancy without the
potential for establishment of home ranges and reproduction. These
natural attributes of wolverines make it difficult to determine their
present range, or trends in range expansion or contraction that may
have occurred in the past. Therefore, we must be cautious when trying
to determine where past wolverine populations occurred, and where
application of conservation actions may be possible in the future.
Aubry et al. (2007, entire) represents the best available science
on the wolverine's geographic range in the contiguous United States.
This study (2007, pp. 2147-2148) 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. Aubry et al.'s (2007) 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 extralimital records (i.e.,
records from outside of established, reproducing populations). Aubry et
al. (2007, p. 2155) concluded that these records represent individuals
dispersing from natal ranges that often end up in habitats that cannot
support wolverines, and their use in determining the potential range of
wolverine can overestimate the area that can actually be used by
wolverines for home ranges and breeding.
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 and encompass the time
during which wolverine numbers and distribution were hypothesized to be
at their lowest, in the first half of the 1900s (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 an earlier low
(Aubry et al. 2007, pp. 2148-2149). Current records are considered by
Aubry et al. (2007, p. 2148) to be a reliable depiction of where
populations occur now.

Wolverine Distribution in the Contiguous United States

Using data from Aubrey et al. 2007, we assessed the historical,
recent, and current distribution data for each of six geographical
regions to determine the likelihood of the presence of historical
populations (rather than extralimital dispersers). Table 1 illustrates
wolverine numbers in the six geographic areas assessed by Aubry et al.
(2007, Table 1). More detail on wolverine distribution over time is
included in the text that follows.

[[Page 12933]]

Table 1.--Verifiable and Documented Records of Wolverine Occurrence in the Contiguous United States by Region and State
[Reproduced from Aubrey et al. 2007, p. 2151]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Historical records Recent records Current
---------------------------------------------------------------------------------------------------------------------------------- records Most recent
Region and State ------------- verifiable
1800s 1901-1910 1911-1920 1921-1930 1931-1940 1941-1950 1951-1960 1961-1970 1971-1980 1981-1994 1995-2005 record
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific Coast Mountains:
Washington...................... 17 3 7 0 0 1 1 10 3 4 7 2003
Oregon.......................... 0 0 1 1 0 0 0 2 2 2 0 1992
California...................... 11 7 9 30 0 0 1 0 0 0 0 1922
Rocky Mountains:
Idaho........................... 6 5 5 2 0 3 4 5 5 \a\ 31 \b\ 16 2005
Montana......................... 6 1 1 0 4 9 39 14 \c\ 121 \d\ 149 \e\ 187 2005
Wyoming......................... 10 6 1 1 0 0 0 1 0 0 \f\ 12 2005
Utah............................ 8 0 1 1 0 0 0 0 0 0 0 1921
Nevada.......................... 0 0 0 0 0 0 0 0 1 0 0 1972
Colorado........................ 22 7 5 0 0 0 0 0 0 0 0 1919
New Mexico...................... 1 0 0 0 0 0 0 0 0 0 0 1860
Central Great Plains:
North Dakota.................... 35 0 1 0 0 0 0 0 0 0 0 None
South Dakota.................... 0 0 0 0 0 0 0 1 0 0 0 1962
Nebraska........................ 1 0 0 0 0 0 0 0 0 0 0 1887
Great Lakes:
Minnesota....................... 6 0 1 2 1 0 0 1 0 0 0 1899
Wisconsin....................... 12 1 0 1 0 0 0 0 0 0 0 \g\ 1800s
Michigan........................ 11 0 0 1 0 0 0 0 0 0 0 1868
Upper Midwest:
Iowa............................ 0 0 0 0 0 0 1 0 0 0 0 1960
Indiana......................... 2 0 0 0 0 0 0 0 0 0 0 None
Ohio............................ 0 0 0 0 0 1 0 0 0 0 0 1943
Northeast:
Pennsylvania.................... 4 0 0 0 0 0 0 0 0 0 0 None
New York........................ 3 0 0 0 0 0 0 0 0 0 0 1811
New Hampshire................... 0 0 2 0 0 0 0 0 0 0 0 None
Vermont......................... 3 0 0 0 0 0 0 0 0 0 0 None
Maine........................... 1 0 0 0 0 0 0 0 0 0 0 None
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Includes 16 initial capture locations obtained from 1992 to 1994 during a radiotelemetry study.
\b\ Includes 3 initial capture locations obtained in 1995 during a radiotelemetry study and 4 initial capture locations obtained from 2003 to 2005 during a radiotelemetry study.
\c\ Includes 94 harvest records from 1974 to 1980 compiled by the MT Department of Fish, Wildlife, and Parks and 24 wolverines that were radiocollared by Hornocker and Hash (1981) in
northwestern MT from 1972 to 1977.
\d\ Includes 146 harvest records from 1981 to 1994 compiled by the MT Department of Fish, Wildlife, and Parks.
\e\ Includes 115 harvest records from 1995 to 2004 compiled by the MT Department of Fish, Wildlife, and Parks and 49 initial capture locations obtained from 2002 to 2005 during radiotelemetry
studies.
\f\ Includes 9 initial capture locations obtained from 1998 to 2005 during telemetry studies.
\g\ Jackson (1954) found 2 wolverine specimens in a cave in southwestern WI in 1920 that he estimated had been in the deposit for > 50 years.

[[Page 12934]]

Northeast and Upper Midwest. The low number of records and the
scattered nature of their distribution suggest that wolverines were
likely to have been occasional transients to the area and not present
as a reproducing population after 1800.
Great Lakes. The low number of verifiable records in this area of
relatively high human population density (compared with, for example,
the Rocky Mountains) 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 beginning in
the 1800s, and currently wolverines occupy only the northern portion of
the province, a distance of over 650 km (404 mi) from the U.S. border
(COSEWIC 2003, p. 9). The pattern of declining numbers of records for
the Great Lakes region 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 farther north into Canada after 1900.
Central Great Plains. The lack of verifiable and mappable records
from the Great Plains States leaves little evidence on which to
determine if reproducing populations of wolverines ever inhabited this
area. Thirty-five of 36 records from North Dakota are from the journals
of a single fur trader, and it is not clear that the records represent
actual collection localities or localities where trades or shipments
occurred (Aubry et al. 2007, entire). The habitat relationships of
wolverines include the Hudsonian life zone, subarctic, and tundra with
persistent spring snow, all features that the Central Great Plains lack
and lacked throughout the historic period (Aubry et al. 2007, pp. 2151-
2152). Therefore, it is unlikely that these records represent
established wolverine individuals or populations, or that this area
contained wolverine habitat.
Rocky Mountains. Five Rocky Mountains States (Idaho, Montana,
Wyoming, Colorado, and Utah) as a region contain numerous wolverine
records over all time intervals. Mappable records appear to coalesce
around several areas that may have been population centers, such as
central Colorado, the Greater Yellowstone Area, and northern Idaho/
northwestern Montana. The large number of verifiable and mappable
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 interval. During the recent interval, the lack of records
for Colorado and Utah suggest that the southern Rocky Mountain
population of wolverines was extirpated by the middle 1900s, concurrent
with widespread systematic predator control by government agencies and
livestock interests. The northern Rocky Mountain population (north of
Wyoming) was reduced to historic lows during the early 1900s, and then
increased dramatically in the second half of the 1900s as predator
control efforts subsided and trapping regulations became more
restrictive (Aubry et al. 2007, p. 2151). This increase may indicate
that the population rebounded from historic lows in this period, but we
cannot rule out that the apparent rebound is an artifact of improved
monitoring of wolverine trapping by government agencies. Wolverine
records from 1995 to 2005 show that wolverine populations currently
exist in the northern Rocky Mountains. Ongoing legal trapping in
Montana removes an average of 10.5 individuals from this population
each year (Montana Department of Fish, Wildlife, and Parks 2007, p. 2).
During all time periods, populations of wolverines in British Columbia
and Alberta may have been a source of surplus wolverines during
population lows (COSEWIC 2003, pp. 18-19).
Pacific Coast. Historically, records from Washington, Oregon, and
California clearly coalesced around two population centers in the North
Cascades and the Sierra Nevada. Records from these areas are separated
by a lack of historic records in southern Oregon and northern
California, indicating that the 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 North
Cascades wolverines were separated for at least 2,000 years prior to
extirpation of the Sierra Nevada population (Schwartz et al. 2007, p.
2174). One Sierra Nevada record exists from after 1930, indicating that
this population was extirpated in the first half of the 1900s
concurrent with widespread systematic predator control programs.
Records from the North Cascades continue into present times in
relatively small numbers, indicating a population persists in this
area. Records from British Columbia, Canada indicate that the North
Cascades population may be connected with, and possibly dependent on,
the larger Canadian population for viability over the long term.

Summary of Wolverine Distribution Patterns in the Contiguous United
States

Historical wolverine records were found across the northern tier of
the lower 48 States with peninsular extensions south into the southern
Rockies and the Sierra Nevada (Aubry et al. 2007, p. 2152).
Currently, wolverines appear to be distributed in two regions in
the lower 48 States: the North Cascades in Washington (and possibly
Oregon), and the northern Rocky Mountains in Idaho, Montana, and
Wyoming. Wolverines were extirpated in historical times from the Sierra
Nevada and the southern Rocky Mountains. We conclude that the current
range of the species in the contiguous United States includes the North
Cascades Mountains and the northern Rocky Mountains.
We also conclude that wolverines likely either did not exist as
established populations or were extirpated prior to settlement and the
compilation of historical records in the Great Lakes region. 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 evidence that they did.
No evidence in the historical records suggests that wolverines were
ever present as established populations in the Great Plains, Midwest,
or Northeast.

Habitat Relationships and Wolverine Distribution in the Contiguous
United States

Aubry et al. (2007, pp. 2152-2156) compared several broad-scale
habitat types to historic, recent, and current wolverine records to
investigate correlations in habitat use and determine what habitat
types might best predict wolverine occurrence. Spring snow cover (April
15 to May 14) is the best overall predictor of wolverine occurrence.
Snow cover during the denning period is essential for successful
wolverine reproduction rangewide (Hatler 1989, p. iv; Magoun and
Copeland 1998, p. 1317; Inman et al. 2007c, pp. 71-72; Persson 2007, p.
1). Wolverine dens tend to be in areas of high structural diversity
such as logs

[[Page 12935]]

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 of logs and
boulders where they produce offspring. This behavior presumably
protects the 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;
Bj[auml]rvall et al. 1978, p. 23).
All of the areas in the lower 48 States for which good evidence of
persistent wolverine populations exists (i.e., Cascades, Sierra Nevada,
northern and southern Rockies) contain large and well-distributed areas
with deep snow cover that persists through the wolverine denning period
(Brock et al. 2007, pp. 36-53; Aubry et al. 2007, p. 2154). The Great
Plains, Great Lakes, Midwest, and Northeast lack the spring snow
conditions thought to be required by wolverines for successful
reproduction (Aubry et al. 2007, p. 2154). This finding supports the
exclusion of the Great Plains, Great Lakes, Midwest, and Northeast from
the current range of wolverines. Whether wolverines once existed as
established populations in any of these regions is unknown, but the
consistent lack of deep spring snow in these regions appears to
currently preclude the wolverine's presence as a reproducing
population.
Large areas of habitat with characteristics suitable for wolverines
still occur in the southern Rocky Mountains and Sierra Nevada where
wolverines have been extirpated (Aubry et al. 2007, p. 2154; Brock et
al. 2007, p. 26). The occurrence data suggest that wolverine
extirpations in these areas were coincidental with systematic predator
eradication efforts in the early 1900s, which have been discontinued
for many years. Wolverines failed to recolonize these areas since the
cessation of eradication programs, by the mid-20th century, of
widespread predator control efforts. This may be the result of the long
dispersal distance between these areas and extant populations.
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 self-sustaining
populations prior to human-induced extirpation, and where
reestablishment of populations is possible given current habitat
conditions and management (the Sierra Nevada mountains in California
and southern Rocky Mountains in Colorado); 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 in the foreseeable
future (Great Plains, Midwest, Great Lakes, and Northeast). Further, on
the basis of the historic and current records and distribution of
suitable habitat, we consider the current range of wolverines to
include suitable habitat in the North Cascades of Washington and
Oregon, and northern Rocky Mountains of Idaho, Wyoming, and Montana.

Wolverine Population Estimate for the Contiguous United States

Current population level and trends remain unknown because no
systematic population census exists over the entire current range of
the wolverine in the lower 48 States. However, we can estimate the
potential carrying capacity of a population in a given region by using
available data on population density, extent of habitat, and wolverine
distribution. Using the projections of wolverine habitat found in Brock
et al. (2007, pp. 36-53), Montana, Idaho, and Wyoming could potentially
support between 499 and 655 individual wolverines (Inman 2007a,
entire). This range is almost certainly an overestimate of actual
wolverine numbers because it assumes that all suitable habitat is
currently occupied, which is not the case (Murphy et al. 2007, p. 2).
Therefore, we consider the lower range estimate of about 500 wolverines
from Inman (2007a, entire) to be a reasonable estimate of the current
wolverine population in the northern Rocky Mountains. The three
northern Rocky Mountain States provide the bulk of currently occupied
habitat in the contiguous United States, with the only additional known
occupied area being the North Cascades mountain range in Washington
State. The size of the North Cascades population is unknown, but is
likely to be much smaller than the northern Rocky Mountain population
due to the small size of the occupied area (Aubry et al. 2007, Fig. 4)
and is unlikely to increase the estimated population significantly.

Distinct Vertebrate Population Segment (DPS)

Under section 4(a)(1) of the Act, we must determine whether any
species is an endangered species or a threatened species because of any
of the five threat factors identified in the Act. Section 3(16) of the
Act defines ``species'' to include ``any subspecies of fish or wildlife
or plants, and any distinct population segment of any species of
vertebrate fish or wildlife which interbreeds when mature'' (16 U.S.C.
1532 (16)). To interpret and implement the distinct population segment
portion of the definition of a species under the Act and Congressional
guidance, the Service and the National Marine Fisheries Service (now
the National Oceanic and Atmospheric Administration-Fisheries)
published, on February 7, 1996, an interagency Policy Regarding the
Recognition of Distinct Vertebrate Population Segments under the Act
(DPS Policy; 61 FR 4722). The policy allows for more refined
application of the Act that better reflects the conservation needs of
the taxon being considered, and avoids the inclusion of entities that
may not warrant protection under the Act.
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 Lists
of Endangered and Threatened Wildlife and Plants, reclassification, and
removal from the Lists. They are: (1) Discreteness of the population
segment in relation to the remainder of the taxon; (2) the 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, endangered or threatened).
Discreteness refers to the 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 information. If we determine that a
population segment is 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 contiguous United States, including the
northern Rocky Mountains and the North Cascades.

[[Page 12936]]

Analysis for 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
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 (see
``International Border Issues'' section below for a discussion of the
standard set by section 4(a)(1)(D)). Below is our discussion of the
wolverine population within the contiguous 48 United States relative to
the discreteness criterion of the DPS policy.

Markedly Separated From Other Populations of the Taxon

The population of the North American wolverine addressed in the
petition, and that we have evaluated for consideration as a DPS,
incorporates wolverine populations south of the international border
with Canada, inclusive of the States of Idaho, Montana, Washington, and
Wyoming (hereafter referred to as the U.S. population). The U.S.
population is connected to wolverine populations in Canada and is
likely dependent on them to some degree for maintaining genetic
diversity. Therefore, the U.S. population of the North American
wolverine does not meet the markedly separated criterion of the DPS
Policy.

International Border Issues

A population segment of a vertebrate species may also be considered
discrete if it is delimited by international governmental boundaries
within which 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. Section
4(a)(1)(D) of the Act is the factor concerning the adequacy of existing
regulatory mechanisms in the Act's ``5-factor'' analysis for
determining whether a species is threatened or endangered. In assessing
a population for discreteness based on delimitation by international
governmental boundaries, we focus specifically on whether the factors
named above are significantly different between the two countries
because of the inadequacy of existing regulatory mechanisms. In order
to demonstrate that a population is discrete based on international
governmental boundaries, it is not enough that there are differences in
control of exploitation, management of habitat, conservation status, or
regulatory mechanisms across the international boundary; the
differences must be significant and relate to inadequate regulatory
mechanisms.. Following is our assessment of the U.S. population and
wolverines in the rest of North America in terms of differences in
control of exploitation, management of habitat, conservation status,
and regulatory mechanisms.

Differences in Management of Habitat

Wolverine habitat in North America occurs in arctic, sub-arctic,
and alpine habitats, and typically in areas remote from human presence
and development. In the contiguous United States, wolverines are
restricted to high-elevation habitats in the Rocky Mountains and North
Cascades containing the arctic and sub-arctic conditions that they
require (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). 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). In both
the contiguous United States and Canada, little habitat management
occurs in areas frequented by wolverines. Therefore, we find that there
are no significant differences in management of habitat for wolverines
that relate to the status of the species between the contiguous United
States and Canada.

Differences in Conservation Status

Biological Status

Throughout its current range in Canada and Alaska, wolverines exist
in well-distributed, interconnected, large populations. Conversely,
wolverines in the contiguous United States appear to exist in small,
fragmented, and semi-isolated populations that put them at greater risk
of being lost due to catastrophic or stochastic events than those
populations to the north in Canada and Alaska. These risks result 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.
These three factors are explained in more detail below; in addition, we
summarize how they relate to section 4(a)(1)(D) of the Act.

Small Total Population Size

The total population sizes for wolverines in Canada and Alaska, and
the contiguous United States, differ by more than an order of
magnitude. As explained in the ``Wolverine Population Estimate for the
Contiguous United States'' section above, the contiguous U.S.
population likely numbers approximately 500 adult individuals (Inman
2007a, entire). This total population is divided into smaller sub-
populations inhabiting semi-isolated habitat fragments in major
mountain ranges (Aubry et al. 2007, Figs. 2b, 4). The population in
western Canada is much larger--estimated at 15,089 to 18,967
individuals (COSEWIC 2003, p. 22). Wolverine population size in Alaska
is unknown; however, the average annual harvest consistently exceeds
500 individuals, and the population does not appear to be in decline
based on trapper reports and the assessments of State wildlife managers
(ADF&G 2004, entire). If the population is truly not declining, it is
likely to number over 8,000 individuals, calculated using demographic
data in Lofroth and Ott (2007, pp. 2196-2198), and assuming sustainable
annual harvest of 6 percent (if 500 represents 6 percent of the
population, total population equals 8,333). Wolverine populations
number 2,089 to 3,567 in British Columbia and 1,500 to 2,000 in Alberta
(COSEWIC 2003, p. 22), the two provinces immediately adjacent to the
contiguous U.S. population. Small populations, such as the contiguous
U.S. population, face higher extinction risk than large ones such as
the Canada and Alaska population (Pimm et al. 1988, p. 762).

Effective Population Size

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). Effective
population size may be less than actual population size if the
population has any of the following characteristics: (1) Unequal sex
ratio, (2) individuals have a disproportionate probability of
contributing offspring to the next generation, (3) population size

[[Page 12937]]

fluctuates over time, and (4) generations overlap such that individuals
may reproduce in more than one generation. 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, pp.
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 the short-term effective population size
should not be less than 50, and the long-term 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). There are
two main ways to estimate the effective population size of populations:
demographic and genetic. Demographically-based methods incorporate life
history parameters, such as unequal sex ratios, fluctuations in
population size over time, and variance in reproductive success, into
abundance and demographic models of a species. Genetically-based
methods use multi-locus genetic data to estimate an effective
population size (Tallmon et al. 2004, p. 979; Waples 2006, pp. 171-178;
Tallmon et al. 2007, entire).
Effective population for wolverines in the Rocky Mountains averaged
39 (Schwartz 2007, entire). This effective population size is
exceptionally low (Schwartz 2007, entire), and is below what is
required for short-term maintenance of genetic diversity.
The concern with the low effective population size is highlighted
by recent research determining that at least 400 breeding pairs would
be necessary to sustain the long-term genetic viability of the
contiguous U.S. wolverine population (Cegelski et al. 2006, p. 197).
However, the entire population is estimated to consist of only 500
individuals (Inman 2007a, entire), with a substantial number of them
being nonbreeding subadults. Furthermore, the contiguous U.S.
population appears to be split into at least five smaller
subpopulations (North Cascades, Crazybelts, Idaho, Greater Yellowstone
Area, and northern Montana) which are semi-isolated from each other,
meaning that genetic exchange does not occur frequently enough to
prevent genetic drift and loss of genetic diversity (Cegelski et al.
2006, p. 206).
Genetic studies have highlighted the essential role that genetic
exchange plays in maintaining genetic diversity in small wolverine
populations. Genetic drift has occurred in the remaining populations in
the contiguous United States where wolverines contain four of nine
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). 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 (Cegelski et al. 2006,
p. 205). 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). As stated previously, the
low effective population size and accompanying reduction in genetic
diversity is a concern because populations with low genetic diversity
are more vulnerable to extinction.
No effective population size estimate exists for populations in
Canada or Alaska. However, none of the Canadian or Alaskan populations
tested show signs of genetic drift or inbreeding (Kyle and Strobeck
2001, p. 343; Cegelski et al. 2006, p. 209), and all Canadian and
Alaskan populations contain higher genetic variation than the U.S.
northern Rocky Mountain populations (Kyle and Strobeck 2001, p. 341).
In addition, because of the large and contiguous nature of the
populations (based on habitat contiguity and genetic similarity, see
``Habitat Availability and Connectivity'' below) (Kyle and Strobeck
2002, p. 1146; Cegelski et al. 2006, p. 209), and the relatively high
genetic diversity in Canada and Alaska, we conclude that the effective
population size is large enough to not be a cause for conservation
concern. This information indicates that the populations in Alaska and
Canada are less vulnerable to extinction pressures associated with a
low effective population size.
The small effective population size in the contiguous U.S.
wolverine population has led to inbreeding and consequent loss of
genetic diversity (Cegelski et al. 2006, p. 208). Over time, if the
current effective population size remains stable, the population will
be at risk of extinction due to inbreeding depression or stochastic
demographic effects (Frankham 1995, p. 795). The small effective
population size in the contiguous United States contrasts with the
situation in 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). Due to the lack of inbreeding reported for
these populations, it is likely that effective population sizes are
much larger than in the contiguous United States. Although these
differences in biological conservation status between the United States
and Canadian wolverine populations exist, they are not significant in
light of section 4(a)(1)(D).

Habitat Availability and Connectivity

Wolverine habitat in the contiguous United States consists of
small, isolated ``islands'' of high-elevation, alpine habitats
containing sufficient depth of snow during the denning period,
separated from each other by low valleys of unsuitable habitats
(Copeland 2007, Map 1). The large distances between suitable wolverine
habitats result in wolverines existing in an archipelago of semi-
isolated, suitable habitats near mountain tops, surrounded by a sea of
unsuitable habitats. Wolverines occupy habitat in a high-elevation band
from 2,100 m to 2,600 m (6,888 ft to 8,528 ft) in the mountains of the
lower 48 States. The intervening valleys in this area range from 975 m
to 1,500 m (3,198 ft to 4,920 ft), and are unsuitable for long-term
wolverine habitat because they do not have the snow conditions or other
habitat features required by wolverines (Aubry et al. 2007, pp. 2151-
2153).
The low population densities and reduced genetic diversity of
wolverines in the contiguous United States means that, to avoid further
inbreeding or local extirpation due to demographic stochasticity,
regular exchange of individual wolverines between islands of habitat
must occur. Intermountain valleys are increasingly the sites of human
residential and commercial developments and transportation corridors,
and represent semi-permeable barriers to wolverines. Although crossings
of valleys, primarily by males (e.g., Packila et al. 2007, Fig. 2, 3),
have been documented, these crossings are not common, and movements
within valleys occur less frequently than movements in suitable
wolverine habitats (Packila et al. 2007, p. 110).
Wolverine populations in the Canadian Rockies also exist on habitat
islands, but the islands are much larger (Copeland 2007, p. 24) and
host larger populations so that exchange of

[[Page 12938]]

individuals is likely to be less critical for short-term maintenance of
genetic diversity and demographic stability. Farther north into Canada
and Alaska, the climate becomes progressively colder and persistent
spring snow and Hudsonian/arctic/sub-arctic habitat associations occur
progressively lower on mountain slopes, until near the Arctic Circle
where these conditions are found at sea level. Wolverines track these
latitudinal and elevation gradients by inhabiting progressively lower
elevations in northern Canada and Alaska until valley bottom habitats
become suitable habitat and wolverines exist over large expanses of
contiguous habitat in well-connected populations (COSEWIC 2003, pp. 7-
8). In the far north of Canada, wolverine habitat extends into low-
elevation valleys and the vast expanses of low-elevation boreal forest
and tundra. Although these differences in biological conservation
status between the United States and Canadian wolverine populations
exist, they are not significant in light of section 4(a)(1)(D).
In the contiguous United States, wolverines must cross unsuitable
habitats to achieve connectivity among subpopulations, which is
required to avert further genetic drift and continued loss of genetic
diversity (Cegelski et al. 2006, p. 208; Copeland 2007, entire; Brock
et al. 2007, pp. 36-53). The highly fragmented nature of the habitat in
the contiguous United States contributes to the low effective
population size for wolverines in this area by dividing the population
among semi-isolated subpopulations, making the continued persistence of
the population precarious relative to the Canadian population. Canadian
habitats are generally contiguous blocks that have few or no
impediments to demographic or genetic connectivity. The fragmented
nature and distribution of wolverine habitat in the lower United States
results in a contiguous U.S. population that is more vulnerable to
extirpation because of lack of connectivity between subpopulations,
which contributes to inbreeding and reduces the chances of
recolonization of habitat patches after local extinction. Although
these differences in biological conservation status between the United
States and Canadian wolverine populations exist, they are not
significant in light of section 4(a)(1)(D).

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
(State of Washington 2007, p.3); Idaho and Wyoming designate it as a
protected nongame species (State of Idaho 2006, p. 9; State of Wyoming
1996, pp. 151-154); and in Montana it is a regulated furbearer (State
of Montana 2007, p. 2). Oregon, while currently not considered to have
any individuals other than possible unsuccessful dispersers, has a
closed season on trapping of wolverines (State of Oregon 2006, p. 2).
The Canadian government has listed its eastern population of
wolverine in Quebec and Labrador, where it may be extirpated due to
trapping and hunting, and declining caribou herds, as Endangered under
the Species at Risk Act (SARA) (www.speciesatrisk.gc.ca). Because
wolverines in this area appear to have been extirpated since the early
1900s, we do not consider this area to be in the wolverine's current
range, and thus its status is not relevant to the question of whether
significant differences in status exist between Canada and the
contiguous 48 United States. The Western population of wolverine occurs
in eight Canadian Provinces, two of which (British Columbia and
Alberta) are contiguous to the lower 48 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) (http://www.speciActtrisk.gc.ca). 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 (Petersen 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).
Because British Columbia and Alberta are contiguous to a larger,
and currently more robust, portion of the wolverine's range in
northwestern Canada, documented declines in wolverine populations 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 under SARA (Lofroth and Krebs 2007, pp. 2164-2165;
Lofroth and Ott 2007, p. 2193; Petersen 1997, pp. 4-5).

Summary of Differences in Conservation Status

As described above, the wolverine has a range of legal statuses
under State regulations in the United States and Canadian Provincial
designations. The differences in legal conservation status conveyed by
the States and Provinces are mixed in each country, but do not appear
significantly different from each other. Some differences exist in
terms of biological conservation status related to small and effective
population sizes, and habitat availability and connectivity. When
evaluating whether these differences are significant enough to use the
international boundary under the discreteness criterion, our policy
directs that these differences must be significant in light of
4(a)(1)(D) of the Act (61 FR 4725). We have concluded that the
differences in biological conservation status between the United States
and Canadian wolverine populations are not significant in light of
section 4(a)(1)(D) of the Act because these differences appear to be a
result of the relatively small and patchy distribution of wolverine
habitat at the southern terminus of its range in the contiguous United
States rather than as a result of inadequate regulatory mechanisms.
Therefore, we determine that the contiguous United States population of
wolverine is not discrete due to differences in conservation status.

Differences in Control of Exploitation and Regulatory Mechanisms

Contiguous U.S. populations are largely not harvested, with the
exception being an average of 10.5 wolverines taken a year in Montana.
In Canada and Alaska, harvest is widespread within the current range.
Although we do not have comprehensive numbers for the annual wolverine
harvest in Canada, we have estimated a total annual harvest of 719
animals (see Table 2) based on the best information available to us.
The numbers below are likely underestimates because they are based on
reported harvests, which in Canadian territories likely accounts for
only one-fifth to one-third of the total harvest because of unreported
harvest by local communities (Melchoir et al. 1987 as cited in Banci
1994, p. 101).

[[Page 12939]]

Table 2.--Estimated Annual Wolverine Harvest in Canada
------------------------------------------------------------------------
Estimated
Province or territory annual Source
harvest
------------------------------------------------------------------------
British Columbia................... 175 Lofroth and Ott, 2007,
pp. 2196-2197.
Alberta............................ 37 Province of Alberta
2006, p. 14.
Saskatchewan....................... 10 COSEWIC 2003, Table 1.
Manitoba........................... 48 COSEWIC 2003, Table 1.
Ontario............................ 8 COSEWIC 2003, Table 1.
Yukon.............................. 150 COSEWIC 2003, Table 1.
Northwest Territories.............. 209 COSEWIC 2003, Table
1.*
Nunavut............................ 82 COSEWIC 2003, Table
1.[supcaret]
-------------
Total.......................... 719
------------------------------------------------------------------------
*Corrected to adjust for majority being unreported in pelt production
statistics.
[caret] Corrected using Dumond and Krizan 2002 as cited in COSEWIC 2003
p. 17.

Based on these harvest numbers and a minimum population estimate of
15,089 (COSEWIC 2003, p. 22), we conservatively estimate that harvest
in Canada is a minimum of 4.7 percent of the population annually.
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).
An estimated 15,089 to 18,967 wolverines occur in Canada where
suitable habitat is plentiful (COSEWIC 2003, pp. 14-22). Because of
this abundance of habitat, protection and intensive management are not
necessary to conserve wolverines in western Canada. This situation
contrasts with the situation in the contiguous United States, where
habitat is fragmented and limited to higher elevations over portions of
four States (Washington, Idaho, Montana, and Wyoming).
Of the four lower 48 States where the wolverine currently persists,
trapping and hunting of the species is prohibited in all except Montana
where the bulk of the species resides. Montana trapping and hunting
regulations define the wolverine as a furbearer, and establish a 2.5-
month season for both hunting and trapping that runs from December 1 to
February 15. A quota of 1 animal per person, up to a total of 12
wolverines per season across all Wolverine Management Units is
established; the quota limits the number of wolverines that may be
taken in each of three Management Units so that take of animals is
distributed across drainages (State of Montana 2007, pp. 2-3, 5, 8).
Across the border from the U.S. wolverine population, the Canadian
Province of British Columbia defines the wolverine as a commercial
furbearer, and assigns it a Regulated Harvest status as a Class 2
Species under its Fur Management Program, which means it is regulated
regionally in consultation with local trappers. No quotas are
established, but reporting and inspection of carcasses is required in
most regions of the Province. The trapping season is open for 3 to 4
months, from November 1 through January or February, depending on the
region (Province of British Columbia 2007, pp. 90-96). Approximately
175 wolverines are harvested each year under this system (out of a
total estimated population of 3,532), equating to a harvest of 5
percent (Lofroth and Ott 2007, pp. 2196-2197). However, as stated
above, in Canada, due to local use, a significant portion of the
harvest may go unreported.
The Canadian Province of Alberta has regulated wolverine trapping
since 1989. An average of 37 animals per year is harvested within the
Province (Province of Alberta 2006, p. 14). Trapping seasons are
established for Fur Management Zones (FMZs) within the Province and run
for 3 months, from November 1 to January 31. Quotas are designated in 6
FMZs, and establish an annual trap limit of 1 wolverine per trapper in
each Wildlife Management Unit (Province of Alberta 2006, p. 8). Two
additional FMZs, that comprise a large area of southeastern Alberta,
are closed to trapping (Province of Alberta 2006, pp. 8, 11, 14);
however, these areas are outside the species' normal range (Petersen
1997, p. 5) and, although they are adjacent to the United States, are
not adjacent to wolverine populations in the United States.
The regulation of exploitation of wolverines is mixed within its
current range in the contiguous United States, Alaska, and Canada.
Controls on the exploitation of wolverine exist in the contiguous
United States, with an average of 10.5 wolverine taken in Montana (2.1
percent of the estimated U.S. population of 500), the only State
allowing trapping or hunting of wolverine. In Alaska, an average of 500
wolverines are harvested per year from a population of unknown size
(assuming a 6 percent harvest rate, the population would be
approximately 8,000 individuals). In Canada, an average of 719
wolverines are harvested per year (4.7 percent of a population of
approximately 15,000; see table 2).
We conclude that differences in control of exploitation and
regulatory mechanisms between the contiguous United States and Canada
are not significantly different. When evaluating whether differences
are significant enough to use the international boundary under the
discreteness criterion, our policy directs that these differences must
be significant in light of 4(a)(1)(D) of the Act (61 Federal Register
4725). We conclude that the differences in control of exploitation
between the United States and Canadian wolverine populations are not
significant in light of section 4(a)(1)(D) of the Act because in both
countries exploitation appears to be adequately regulated according to
what the overall population can sustain. This conclusion is supported
by the fact that wolverine populations appear to be able to sustain the
current rate of mortality due to trapping and hunting (approximately 6
percent in Alaska, 4.7 percent throughout western Canada, and 2.1
percent in the contiguous United States). Therefore, we determine that
the contiguous United States population of wolverine is not discrete
due to differences in control of exploitation.

Summary for Discreteness

The international boundary between Canada and the United States
currently leads to some differences in the control of exploitation and
conservation status of the wolverine. However, we find that these
differences between Canada and the contiguous United States do not

[[Page 12940]]

result in significant differences in light of section 4(a)(1)(D) of the
Act because they are not the result of inadequate regulatory mechanisms
that place the U.S. population at risk. Therefore, we have determined
that the U.S. portion of the range does not meet the discreteness
criteria in our DPS Policy (61 FR 4725).
The Service finds that the existing data do not indicate that North
American wolverines in the contiguous United States are ``markedly
separated'' from those in Canada and Alaska. Consequently, the Service
is unable to conclude at this time that the petitioned entity is
discrete according to our DPS policy. Therefore, the North American
wolverine in the contiguous United States does not qualify as a
distinct population segment and is not a listable entity under the Act.
Because we have determined that the population of the North American
wolverine in the contiguous United States is not discrete and therefore
not a DPS and a listable entity under the Act, we do not need to
consider whether the population is significant with regards to the DPS
policy or the conservation status pursuant to Section 4(a)(1) of the
Act.

Significant Portion of the Range Analysis

Because the petitioned action was to list the wolverine in the
contiguous United States, after determining that the wolverine in this
portion of its range is not a distinct population segment (DPS), we
analyzed whether it would constitute a significant potion of the range
of the North American subspecies. On March 16, 2007, a formal opinion
was issued by the Solicitor of the Department of the Interior, ``The
Meaning of `In Danger of Extinction Throughout All or a Significant
Portion of Its Range' '' (DOI 2007). A portion of a species' range is
significant if it is part of the current range of the species and is
important to the conservation of the species because it contributes
meaningfully to the representation, resiliency, or redundancy of the
species. The contribution must be at a level such that its loss would
result in a decrease in the ability of the species to persist.
In determining whether the petitioned entity warranted listing as
threatened or endangered throughout a significant portion of its range,
we first determine whether there is substantial information indicating
that (1) the petitioned entity constitutes a significant portion of the
range, and (2) the species may be in danger of extinction there or
likely to become so within the foreseeable future. In practice, a key
part of this analysis is whether the threats are geographically
concentrated in some way. If the threats to the species are essentially
uniform throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the range that are unimportant to the conservation of
the species, such portions will not warrant further consideration.
If we identify any portions that warrant further consideration, we
then determine whether the species is threatened or endangered in any
significant portion. If we determine that a portion of the range is not
significant, we do not determine whether the species is threatened or
endangered there.
The terms ``resiliency,'' ``redundancy,'' and ``representation''
are intended to be indicators of the conservation value of portions of
the range. Resiliency of a species allows it to recover from periodic
disturbances. A species will likely be more resilient if large
populations exist in high-quality habitat that is distributed
throughout its range in a way that captures the environmental
variability available. A portion of the range of a species may make a
meaningful contribution to the resiliency of the species if the area is
relatively large and contains particularly high-quality habitat, or if
its location or characteristics make it less susceptible to certain
threats than other portions of the range. When evaluating whether or
how a portion of the range contributes to resiliency of the species, we
evaluate the historical value of the portion and how frequently the
portion is used by the species, if possible. The range portion may
contribute to resiliency for other reasons; for instance, it may
contain an important concentration of certain types of habitat that are
necessary for the species to carry out its life-history functions, such
as breeding, feeding, migration, dispersal, or wintering.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This concept
does not mean that any portion that provides redundancy is per se a
significant portion of the range of a species. The idea is to conserve
enough areas of the range so that random perturbations in the system
only act on a few populations. Therefore, we examine each area based on
whether that area provides an increment of redundancy that is important
to the conservation of the species.
Adequate representation ensures that the species' adaptive
capabilities are conserved. Specifically, we evaluate a range portion
to see how it contributes to the genetic diversity of the species. The
loss of genetically based diversity may substantially reduce the
ability of the species to respond and adapt to future environmental
changes. A peripheral population may contribute meaningfully to
representation if there is evidence that it provides genetic diversity
due to its location on the margin of the species' habitat requirements.
Because the petition to list the wolverine only specified the
portion of the subspecies' range in the contiguous United States, we
assessed whether this portion is important to the conservation of the
subspecies because it contributes meaningfully to the representation,
resiliency, or redundancy of the species.
For resiliency, we evaluated whether the contiguous U.S. wolverine
population occupies relatively large or particularly high-quality
habitat, or if its location or characteristics make it less susceptible
to certain threats than other portions of the range. We determined that
the contiguous U.S. wolverine population constitutes a relatively small
area of patchily distributed lower-quality habitat when compared to the
Gulo gulo luscus range overall. Additionally, we find that the
characteristics of the contiguous U.S. wolverine population make it
more susceptible to certain threats than other portions of the range
because of the isolated patchy ``sky island'' habitats at the southern
terminus of its range. Additionally, we evaluated the historical value
of the contiguous U.S. portion of the wolverine range and how
frequently the portion is used by the species, and whether the portion
contains an important concentration of certain types of habitat that
are necessary for the species to carry out its life-history functions,
such as breeding, feeding, migration, dispersal, or wintering. We found
that the contiguous U.S. wolverine population does not meaningfully
contribute to resiliency because the habitats necessary for breeding,
feeding, migration, dispersal, or wintering are found distributed
throughout its range and are not solely found in the contiguous United
States. Therefore, we conclude that the contiguous U.S. wolverine
population does not contribute meaningfully to the resiliency of G. g.
luscus.
In analyzing redundancy, we evaluated whether the contiguous U.S.
portion of the wolverine range is necessary to provide a margin of
safety for the species to withstand catastrophic events. We also
examined the contiguous U.S. portion of the wolverine range to
determine whether that area provides an increment of

[[Page 12941]]

redundancy that is important to the conservation of the species. In
North America, wolverines occur within a wide variety of arctic, sub-
arctic and alpine habitats, primarily boreal forests, tundra, and
western mountains throughout Alaska and Canada, with two small
peninsulas of habitat extending into the North Cascades and the
Northern Rocky Mountains in the contiguous United States. The portion
of the range that extends into the contiguous United States is small in
relation to the entire range of the subspecies. Additionally, the
actual area amount of habitat in the contiguous United States is more
fragmented in nature than habitat found elsewhere throughout the range,
which results in a smaller proportion of actual habitat in the
contiguous U.S. portion than what is generally indicated on ``range''
maps (see ``Habitat Availability and Connectivity'' section above).
Finally, a small proportion of the total wolverine population occurs in
the contiguous United States. Assuming 8,333 wolverine occur in Alaska
(as described in the control of exploitation section above), 15,089
wolverine occur in Canada, and 500 wolverine occur in the contiguous
United States, the contiguous United States portion accounts for only 2
percent of the entire G. g. luscus population. Thus, we determined that
the contiguous U.S. wolverine population does not significantly
contribute to the redundancy of G. g. luscus.
In determining whether the contiguous U.S. wolverine population
contributed to representation, we evaluated whether it contributes to
the genetic diversity of the species. Adequate representation ensures
that the species' adaptive capabilities are conserved. Wolverines in
the contiguous United States contain a subset of the genetic haplotypes
found in the Canadian populations, and therefore do not represent a
unique population. Thus, the species does not meaningfully contribute
to representation of Gulo gulo luscus. The populations in Canada and
Alaska are relatively large and contiguous, and are not dependent on
connectivity to the contiguous U.S. population.
Based on the discussion above, we determined that the contiguous
United States portion of the current range of the North American
wolverine is not significant to the Gulo gulo luscus subspecies, and
therefore does not warrant further consideration to determine if it is
a significant portion of the range that is threatened or endangered. In
addition, we find that historical habitat in the contiguous United
States that is no longer occupied would not raise the status of this
portion of the range as being significant to the subspecies.

Finding

We have carefully assessed the best scientific and commercial
information available regarding threats to the contiguous United States
population of the wolverine. We reviewed the petition, and available
published and unpublished scientific and commercial information. This
12-month finding reflects and incorporates information that we received
during the public comment period or that we obtained through
consultation, literature research, and field visits.
On the basis of this review, we have determined that the contiguous
United States population of the North American wolverine does not
constitute a distinct population segment (DPS) under the Act and
therefore a listable entity unto itself. We also find that the
contiguous United States population of the North American wolverine is
not a significant portion of the range of the North American subspecies
and does not warrant further consideration under the Act. Therefore, we
find that the petition to list the North American wolverine that occurs
in the contiguous United States is not warranted for listing.

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 author of this document is staff of the Mountain-
Prairie Region of the U.S. Fish and Wildlife Service, 134 Union Blvd.,
Ste. 145, Lakewood, Colorado 80228 (also 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: February 28, 2008.
H. Dale Hall,
Director, U.S. Fish and Wildlife Service.
[FR Doc. E8-4197 Filed 3-10-08; 8:45 am]

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