The Wolverine is a bear-like mustelid with massive limbs and long, dense, dark brown pelage, paler on the head, with two broad yellowish stripes extending from the shoulders and joining on the rump. Variable white or yellowish markings are often present on the throat and chest. The tail is bushy. The feet are relatively large (6.5 to 11.3 centimeters total length) with robust claws. Wolverines weigh between 7 and 32 kilograms and range from 0.9 to 1.1 meters in length. Females average about 10% less than males in linear measurements and 30% less in mass (Ingles 1965, Hall 1981, Nowak 1991).
Wolverines are most similar to Fishers (Martes pennanti) but are nearly twice as large. Fishers also lack the light colored lateral markings of the Wolverine and the tail is less bushy. Badgers have shorter legs and are much lighter colored with a distinctive black and white pattern on the face.
Western Hemisphere Range
Summary of Observations Submitted for Montana
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Records associated with a range of dates are excluded from time charts)
Wolverines in northwestern Montana and Alaska tended to occupy higher elevations in summer and lower elevations in winter (Hornocker and Hash 1981, Whitman et al. 1986). Seasonal ranges were all within a large home range; dispersal movements of more than 300 kilometers are known (Magoun 1985, Gardner et al. 1986).
Wolverines are limited to alpine tundra, and boreal and mountain forests (primarily coniferous) in the western mountains, especially large wilderness areas. However, dispersing individuals have been found far outside of usual habitats. They are usually in areas with snow on the ground in winter. Riparian areas may be important winter habitat. When inactive, Wolverines occupy dens in caves, rock crevices, under fallen trees, in thickets, or similar sites. Wolverines are primarily terrestrial but may climb trees.
In Montana, Hornocker and Hash (1981) found most Wolverine use in medium to scattered timber, while areas of dense, young timber were used least. Wolverines avoided clearcuts and burns, crossing them rapidly and directly when they were entered at all. Hash (1987) reported Wolverines in the Northern Rocky Mountain region were associated with fir, pine, and larch. Aspen stands were also used, as were cottonwoods in riparian areas. Ecotonal areas appeared to be important habitat components (Hash 1987). Hatler (1989) believed Wolverines are not dependant on any particular vegetative habitat type. Banci (1986) reported "habitat requirements appear to be large, isolated tracts of wilderness supporting a diverse prey base, rather than specific plant associations or topography." South of the boreal forest, most habitat descriptions in the literature agree with Grove's (1988) characterization of "large, mountainous, and essentially roadless areas."
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
- Examining the observation records for each species in the state-wide point database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at email@example.com
or (406) 444-3655.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2001. The wild mammals of Montana. Special Publication No. 12. Lawrence, KS: The American Society of Mammalogists. 278 p.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Wetland and Riparian Systems
Wolverines are opportunistic. They feed on a wide variety of roots, berries, small mammals, birds' eggs and young, fledglings, and fish (Hatler 1989). They may attack moose, caribou, and deer hampered by deep snow. Small and medium size rodents and carrion (especially ungulate carcasses) often make up a large percentage of the diet. Prey is captured by pursuit, ambush, digging out dens (Biosystems Analysis 1989), or climbing into trees. They may cache prey in the fork of tree branches or under snow.
Wolverines are generally solitary and wide-ranging. They occur at relatively low densities (e.g., 1 per 65 square kilometers in northwestern Montana) (Hornocker and Hash 1981). Home ranges of males are larger than those of females, with home ranges of up to several hundred square kilometers. The mean annual home range of males was 535 square kilometers in Alaska, and 422 square kilometers in Montana. Female home ranges were 105 square kilometers in Alaska and 388 square kilometers in Montana (Hornocker and Hash 1981). Males in some areas apparently are territorial, but in Montana there was extensive overlap of the ranges of both the same and opposite sexes (Hornocker and Hash 1981). Apparently territory/range size depends on availability of denning sites and food supply (Wilson 1982). Some individuals travel regularly over the same route (Wilson 1982). Available evidence indicates that juveniles disperse usually around 30 to 100 kilometers from their natal range, though dispersal movements of more than 300 kilometers are known (Magoun 1985, Gardner et al. 1986). There are no important predators other than humans.
Although the Wolverine usually breeds in summer, the event may occur from April to October. Implantation is delayed and does not occur until winter. Gestation lasts 7 to 9 months; active gestation is 30 to 40 days. One to six (usually 2 to 4) young are born January through April, mainly in February or March, and reportedly April through June in the Pacific states (Ingles 1965), in a den among rocks or tree roots, in a hollow log, under a fallen tree, or in dense vegetation, including sites under snow. Young are weaned beginning at about 7 or 8 weeks, and separate from the mother in the fall. They are sexually mature generally in the second or third year. Males sexually mature sometimes as yearlings (Alaska and Yukon); males over three years old were sexually mature in British Columbia. Some females mature at 12 to 15 months and produce their first litter when two years old (Wilson 1982). In some areas, females may produce litters only every 2 or 3 years. In British Columbia, most mature females were reproductively active. The Wolverine lives to an age of up to about 10, or sometimes 15 to 18, years.
On 13 August 2014, the U.S. Fish and Wildlife Service published a notice in the Federal Register indicating that, "While it is clear that the climate is warming, after carefully considering the best available science, the Service has determined that the effects of climate change are not likely to place the wolverine in danger of extinction now or in the foreseeable future. As a result, the wolverine does not meet the statutory definition of either a “threatened species” or an “endangered species” and does not warrant protection under the ESA." Additional information on the species' management can be found on the U.S. Fish and Wildlife Service's Species Account
Wolverines were nearly extinct in Montana during the early 1900's and have been increasing in numbers and range since. Recovery originated in northwestern Montana and subsequently spread to its current range (Newby and Wright 1955, Newby and McDougal 1964).
Wolverines are classified as a furbearer in Montana. However, the trapping season is currently suspended with a statewide quota of zero.
- Literature Cited AboveLegend: View WorldCat Record View Online Publication
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- Additional ReferencesLegend: View WorldCat Record View Online Publication
Do you know of a citation we're missing?
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