[Federal Register: October 21, 2003 (Volume 68, Number 203)]
[Page 60112-60115]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

Endangered and Threatened Wildlife and Plants; 90-day Finding for 
a Petition To List as Endangered or Threatened Wolverine in the 
Contiguous United States

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding for a petition to list the wolverine (Gulo gulo luscus) 
in the contiguous United States as threatened or endangered under the 
Endangered Species Act of 1973, as amended. We find the petition and 
additional information available in our files did not present 
substantial scientific or commercial information indicating that 
listing the wolverine in the contiguous United States may be warranted. 
We will not be initiating a further status review in response to this 
petition. We ask the public to submit to us any new information that 
becomes available concerning the status of or threats to this species. 
This information will help us monitor and encourage the conservation of 
this species.

DATES: The finding announced in this document was made on October 15, 
2003. You may submit new information concerning this species for our 
consideration at any time.

ADDRESSES: Data, information, comments, or questions concerning this 
petition should be submitted to the Montana Ecological Services Field 
Office, U.S. Fish and Wildlife Service, 100 North Park Avenue, Suite 
320, Helena, Montana 59601. The petition, finding, and supporting 
information are available for public inspection, by appointment, during 
normal business hours, at the above address. Submit new information, 
materials, comments, or questions concerning this species to the 
Service at the above address.

FOR FURTHER INFORMATION CONTACT: Lori Nordstrom, at the address given 
in the ADDRESSES section (telephone (406) 449-5225; facsimile (406) 449-5339; electronic mail FW6_wolverine@fws.gov).



    Section 4(b)(3)(A) of the Endangered Species Act of 1973, as 
amended (Act) (16 U.S.C. 1531 et seq.), requires that we make a finding 
on whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information to indicate that the 
petitioned action may be warranted. We are to base this finding on all 
information available to us at the time we make the finding. To the 
maximum extent practicable, we must make this finding within 90 days of 
receiving the petition and publish a notice of the finding promptly in 
the Federal Register. Our standard for substantial information with 
regard to a 90-day petition finding is ``that amount of information 
that would lead a reasonable person to believe that the measure 
proposed in the petition may be warranted'' (50 CFR 424.14(b)). If the 
finding is that substantial information was presented, we are required 
to promptly begin a review of the status of the species, if one has not 
already been initiated, under our internal candidate assessment 
    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. The petition 
requests that we list the wolverine within the contiguous United States 
as a threatened or endangered species and designate critical habitat 
for the species.
    On April 19, 1995, we published a notice of our finding 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 (60 FR 19567).
    Since 1995, little new information on wolverine biology, 
distribution, habitat requirements, or possible threats has been 
published. The species is still considered one of the least understood 
medium carnivores. The only new research completed for the contiguous 
United States is that on wolverine ecology in Idaho (Copeland 1996; 
Magoun and Copeland 1998; Edelman and Copeland 1999), and a genetic 
study (Cegelski 2002). Banci (1994) is a compilation of existing 
wolverine information plus suggestions for research or management 
considerations. Additional research on wolverine ecology, current and 

[[Page 60113]]

distribution, population demographics, and habitat requirements is 
underway that should provide better information with which to 
understand the wolverine (Inman et al. 2002; J. Squires, Rocky Mountain 
Research Station, pers. comm. 2003; U.S. Forest Service, in litt. 
    The wolverine has a holarctic distribution. 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 contiguous United States are a part of 
the New World subspecies, G. g. luscus (Kurten and Rausch 1959; 
Pasitschniak-Arts and Lariviere 1995). We follow this currently 
accepted taxonomic treatment, although in the past we recognized other 
taxonomic classifications for wolverine (September 18, 1985; 50 FR 
    The wolverine is the largest terrestrial member of the family 
Mustelidae, with adult males weighing 12 to 18 kilograms (kg) (26 to 40 
pounds (lb)) and adult females weighing 8 to 12 kg (17 to 26 lb) (Banci 
1994). It resembles a small bear with a bushy tail. It has a round, 
broad head; short, rounded ears; and small eyes. There are five toes on 
each foot, with curved and semiretractile claws used for digging and 
climbing (Banci 1994).
    Wolverines are opportunistic feeders, consuming 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; Wilson 1982; Hash 1987; Banci 1994). 
Wolverines have an excellent sense of smell, enabling them to find food 
beneath deep snow (Hornocker and Hash 1981).
    Breeding generally occurs from late spring to early fall. Females 
undergo delayed implantation until the following winter to spring, when 
active gestation lasts from 30 to 40 days (Rausch and Pearson 1972). 
Litters are born between February and April, containing one to five 
kits, with two to three kits being the most common number (Hash 1987). 
Reproductive dens in Idaho were located in snow-covered boulder talus 
in subalpine cirque basins (Copeland 1996; Magoun and Copeland 1998).
    Wolverines have large spatial requirements; the availability and 
distribution of food is likely the primary factor in determining 
wolverine movements and home range (Hornocker and Hash 1981; Banci 
1994). Wolverines can travel long distances over rough terrain and deep 
snow, with adult males generally covering greater distances than 
females (Hornocker and Hash 1981; Banci 1994). Home ranges of 
wolverines are generally extremely large, but vary greatly depending on 
availability of food, gender, age, and differences in habitat. Home 
ranges of adult wolverines range from less than 100 square kilometers 
(km2) to over 900 km2 (38.5 square miles (mi2) to 348 mi2) (Banci 
1994). Copeland (1996) found that annual home ranges of resident adult 
females in central Idaho averaged 384 km2 (148 mi2), while the annual 
home ranges of resident adult males averaged 1,522 km2 (588 mi2).
    In North America, wolverines occur within a wide variety of 
habitats, primarily boreal forests, tundra, and western mountains 
throughout Alaska and Canada, with the southern portion of the 
wolverine range extending into the contiguous United States (Wilson 
1982; Hash 1987; Banci 1994; Pasitschniak-Arts and Lariviere 1995). The 
specific range of the wolverine in the contiguous United States is not 
well understood, preventing us from accurately delineating the historic 
or current range using the information available to us at this time. 
The petitioners state that wolverine were trapped to near or complete 
extinction throughout its former range in the western states in the 
early 20th century. However, information from state and Federal wildife 
experts suggest the species has reoccupied its western range in recent 
years .
    The current range in the contiguous United States is believed to 
include Idaho, Montana, Oregon, Washington, Wyoming, and possibly 
California (Banci 1994). Wolverines have recently been documented in 
Idaho (Copeland 1996), Montana (Inman et al. 2002; B. Giddings, Montana 
Department of Fish, Wildlife and Parks, pers. comm. 2003; J. Squires, 
pers. comm. 2003), Washington (Washington Department of Fish and 
Wildlife, in litt. 1998) and Wyoming (Inman et al. 2002). However, we 
do not know the extent of the historic range. Wolverines reportedly 
occurred in a number of other States historically, including Colorado, 
Maine, Michigan, Minnesota, New Hampshire, New York, North Dakota, 
Utah, and Wisconsin, suggesting a much wider range historically (Wilson 
1982; Hash 1987; Pasitschniak-Arts and Lariviere 1995). The petitioners 
generally stated that wolverines have been extirpated from States in 
the Great Lakes, High Plains, and Northeast. But, as we found in 1995, 
the petition provides no information to confirm the reliability of 
these historic reports. Furthermore, without a better understanding of 
the habitat requirements of the wolverine, we cannot ascertain whether 
habitats in many States were capable of supporting wolverines 
historically, which would help us determine their historic range.
    The wolverine naturally occurs in low densities (Hornocker and Hash 
1981; Hash 1987; Banci 1994). Petitioners state that (1) wolverine 
range and numbers have decreased dramatically since Pre-Columbian times 
due to human activities and developments, and (2) wolverines currently 
number fewer than 1,000 animals across the lower 48 states.
    However, Hornaker and Hash (1981) asserted stable populations on 
their study area in Montana, with high dispersal patterns maintaining 
the stability, rebounding from near extinction in Montana from 1920-
1940 (Newby and Wright 1955).
    Recent surveys in the west indicate that wolverines appear to be 
distributed in the montane regions of Idaho, Montana, Washington and 
Wyoming (Copeland 1996; Washington Department of Wildlife 1998; Inman 
et al. 2002; Giddings pers. comm. 2003; Squires pers. comm. 2003). So, 
despite scant population and abundance information, there are reports 
and surveys to suggest that wolverine may not be likely to become 
threatened in the foreseeable future in the lower 48 states. Wolverines 
are difficult and expensive to study and are rarely observed, so a lack 
of sightings does not necessarily mean that wolverines are not present 
(Banci 1994). There have been few, if any, surveys of wolverines in the 
contiguous United States that were designed to estimate population size 
at even a local scale. As a result, it is scientifically unsound to 
make an estimate of wolverine population size using currently available 
information, particularly for the entire contiguous United States.
    Despite the limitations of available wolverine data, the 
petitioners provided their own estimation of the size of the wolverine 
population for the contiguous United States. They arrived at their 
estimate apparently by creating their own measure of local wolverine 
densities and extrapolating across what they determined to be the 
current range of wolverine. Given the lack of data on wolverine 
population densities even at a local level, using such preliminary 
information to estimate population size is inappropriate.
    Based on what we know about wolverines (i.e., they are found in low 
densities and have large home ranges), we expect wolverine population 
sizes to appear low when compared to other species with different 
population dynamics.

[[Page 60114]]

    At this time, this lack of information prevents us from determining 
whether wolverines in the contiguous United States constitute a 
``distinct population segment'' (DPS), which would make them eligible 
to be listed under the Act. Our Distinct Vertebrate Population Policy 
published in 1996 (61 FR 4722) specifies that we are to use two 
elements to assess whether a population segment under consideration for 
listing may be recognized as a DPS--(1) The population segment's 
discreteness from the remainder of the taxon to which it belongs; and 
(2) the significance of the population segment to the taxon to which it 
belongs. A taxon is the taxonomic group of animals to which the 
population belongs--in this case the subspecies G. g. luscus.
    Under section 4(a) of the Act, we may list a species, subspecies, 
or DPS of vertebrate on the basis of any of five factors--(A) 
Destruction, modification, or curtailment of habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) inadequacy of 
existing regulatory mechanisms; and (E) other man-made or natural 
factors affecting its continued existence. The petition asserts that 
wolverines are subject to threats primarily under Factors A, B, and D. 
The Service used information provided by the petitioners and available 
in its files to address these factors as follows.
    Under Factor A, the petition asserts wolverines have been impacted 
by the loss of roadless areas due to logging practices. However, Banci 
(1994) stated that ``the impacts of logging and associated activities 
on wolverines and wolverine habitat can only be surmised.'' Wolverines 
are generally associated with remote areas and require large expanses 
of land as refugia from human activities, especially during denning. 
Hornocker and Hash (1981) mentioned that wilderness or remote areas, 
with limited human activity, appear to be necessary for viable 
wolverine populations; however, they found no difference in wolverine 
densities between the wilderness and non-wilderness areas of the study, 
nor were there differences in their movement, habitat use, or behavior. 
The non-wilderness portion of the study area was mainly used by humans 
for logging and recreation (Hornocker and Hash 1981). Copeland (1996) 
also found wolverines in areas that were currently being logged.
    The petitioners cite human disturbance of denning habitat, 
particularly snowmobile activity, as a threat to wolverines. New 
research indicates wolverines are sensitive to disturbance when they 
are denning. In two instances female wolverines moved their kits and 
abandoned their dens upon encountering researchers; the kits survived 
the move (Copeland 1996; Magoun and Copeland 1998). Copeland (1996) 
concluded that protection of natal denning habitat is important to the 
persistence of wolverine in Idaho. The petitioners provide general 
information that snowmobile activity is increasing and could expand 
into regions where wolverines occur, but there is a lack of information 
to determine the degree to which snowmobile activity may be increasing 
within wolverine denning habitat or what impact it may be having on 
wolverine populations.
    The petitioners cite landscape fragmentation due to transportation 
corridors and associated developments as a threat to wolverines. The 
Service agrees that development is increasing throughout the contiguous 
United States; however, the level to which landscape fragmentation may 
be affecting wolverines and their ability to meet their habitat 
requirements is unknown because little is known about wolverine range 
and movement. Genetic differentiation among wolverine populations in 
Idaho, Montana, and Wyoming has been documented, suggesting some level 
of isolation among these populations possibly as a result of human-
caused habitat fragmentation (Cegelski 2002). However, given the lack 
of understanding of wolverine habitat regarding factors affecting 
dispersal, all knowledge of possible causes of the genetic differences 
among these populations is speculative at this time.
    Based on the foregoing discussion, we find that the petition does 
not present substantial information to indicate that habitat impacts 
threaten the continued existence of the wolverine in the contiguous 
United States.
    Under Factor B, the petitioners cite trapping as a threat to 
wolverines in the contiguous United States. Over much of the wolverine 
distribution, trapping has been a primary factor in wolverine mortality 
(Banci 1994). Trapping is believed to have played a role in an apparent 
historic decline of wolverine in North America in the late 19th and 
early 20th centuries (Hash 1987). Today, within the contiguous United 
States, the only State where wolverine trapping is legal is Montana. 
Although this trapping season may be detrimental to local wolverine 
populations, it is not known whether trapping in Montana alone 
threatens the continued existence of the wolverine population in the 
contiguous United States. The petitioners also suggest incidental 
trapping and poisoning of wolverines as a threat, but provide no 
supporting information for this assertion.
    Under Factor C, the petitioners mention predation by other large 
predators (e.g., wolves) as a source of wolverine mortality. However, 
this is a natural event and is not considered a threat to the 
persistence of wolverines in the contiguous United States. There is no 
information on diseases that may impact wolverine populations.
    Under Factor D, the petition cites a lack of Federal protection as 
a threat to wolverines because a major part of the wolverine's range 
falls upon lands managed by the U.S. Forest Service (USFS). The USFS 
has designated wolverines as a ``sensitive species'' in Regions 1, 2, 
4, and 6, and ``proposed sensitive'' in Region 5. The Bureau of Land 
Management has determined wolverine to be ``sensetive.'' Conservation 
efforts are planned for various Federal lands and the upcoming USFS 
report will help improve the scant information currently available.
    It is not possible at this time to determine whether management 
actions threaten the continued existence of wolverines in the 
contiguous United States. The USFS is leading a cooperative effort with 
other Federal agencies, States, and Tribes to conduct research and 
studies for the development of a scientifically-based strategy for 
conserving wolverines (USFS, in litt. 2002). Initial work is focused on 
summarizing historic observation data in an effort to delineate 
historic and current range and habitat relationships. Ongoing research 
and surveys will examine wolverine ecology, population demographics, 
distribution, and habitat use with an emphasis on broad-scale movements 
and population connectivity.
    Finally, under Factor E, the petitioners generally cite the 
wolverine's low reproductive rate, sensitivity during denning, and need 
for large areas of unfragmented range and habitat as factors making the 
wolverine vulnerable to extinction. These natural life history 
characteristics distinguish the wolverine from other medium-sized 
carnivores. However, reports and surveys of wolverine from Idaho, 
Montana, Wyoming, and Washington suggest some stability. It is 
important to collect more information on wolverine occurrence, 
distribution, and habitat requirements in addition to developing 
management measures to conserve the species.
    In summary, we find that there is insufficient information in the 
petition or in our files on wolverine habitat requirements or range to 

[[Page 60115]]

whether destruction or modification of wolverine habitat and range is 
occurring to the extent that it affects the status of the wolverine. We 
also found insufficient evidence to indicate that the wolverine 
trapping season in Montana or incidental trapping or poisoning poses a 
threat to the wolverine population in the contiguous United States. The 
paucity of data on wolverine life history and habitat requirements 
leads us to conclude that there is insufficient evidence to determine 
if land and wildlife managers are failing to conserve wolverines. There 
also is insufficient data to determine whether human disturbance is 
negatively impacting wolverine populations on a scale that impacts the 
status of the species.
    We anticipate that ongoing studies of wolverines and, in 
particular, a scientific assessment of wolverines in the contiguous 
United States being led by the USFS that should be available in 2004, 
will improve our understanding of this species in the contiguous United 
    We have reviewed the petition, information submitted by the 
petitioners, other pertinent literature, and information available in 
Service files. We find the petition does not present substantial 
information to indicate that petitioned action may be warranted. This 
finding is based on insufficient information to--(1) Determine whether 
the wolverine in the contiguous United States constitutes a DPS under 
the Act, (2) understand possible threats to the wolverine, or (3) 
determine whether or not the species is declining in the contiguous 
United States.
    References Cited: A complete list of all references cited herein is 
available upon request from the Montana Field Office (see ADDRESSES).
    Author: The primary authors of this document are Katrina Dixon and 
Lori Nordstrom, Montana Field Office, Helena, Montana.

    Authority: The authority for this action is the Endangered 
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: October 15, 2003.
Marshall P. Jones, Jr.,
Director, Fish and Wildlife Service.
[FR Doc. 03-26453 Filed 10-20-03; 8:45 am]