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Photo Courtesy of Utah Division of Wildlife Resources
Wolverine
Gulo gulo
NatureServe conservation status
Global (G-rank): G4
State (S-rank): S2
- Reason: 24 occurrences of this species in Utah are known, but at least 17 of these are historical. The species is believed, based on recent (1990) sightings judged to be reliable, to be extant in the state, and there may be as many as five or six extant occurrences. Recent evidence suggests that the species is still present in parts of the Wasatch Mountains, the Uinta Mountains, and mountains of the central part of the state (Sanpete County).
External links
General information
The wolverine, Gulo gulo, has a holarctic distribution, occurring in the northern parts of North America, Asia, and Europe. The species was probably never common in Utah, but it previously occurred (and still may occur) in the high mountainous areas of the state. Wolverines prefer alpine tundra and mountain forest habitats that are not frequented by humans. In fact, human impacts have caused a great reduction in wolverine distribution during the past 100 years.
Females typically produce a litter of two to three young every two years or so. Wolverines are opportunistic feeders, consuming eggs, roots, carrion, and many types of animals, including deer and moose trapped in deep snow. Wolverines are often nocturnal and are active year-round. They are generally solitary, and may range over large areas searching for food.
Phenology
Active throughout the year. Active both day and night but primarily nocturnal.
Species range
This species formerly occurred in Utah in the Wasatch Mountains, the Uinta Mountains, the La Sal Mountains, and the high plateaus and mountains of the central part of the state south to Piute and Garfield counties. It is believed to be extant in the higher and remoter parts of these areas. McKay (1991) reviewed the status of the species in Utah and compiled and assessed recent reports (through 1990). The two most recent sightings (as of 1990) that were considered by her to be probably valid were: one in the Ashley National Forest, Daggett County, 20 July 1990; another in the Manti-La Sal National Forest, Sanpete County, 24 July 1990. Another sighting of this species was made 4 July 1992 only 1/2 mile from the location of the location of the 1990 sighting in the Manti-La Sal National Forest, Sanpete County. A male was shot 15 March 1979, supposedly in Utah, and was examined by Utah Division of Wildlife Resources personnel; the locality is not known, and there is some doubt as to whether it was actually killed in Utah rather than in Colorado. Occurrences are known in Cache, Weber, Morgan, Summit, Daggett, Uintah, Duchesne, Salt Lake, Utah, Wasatch, Sanpete, Piute, Garfield, and San Juan counties.
Migration
Tends to occupy higher elevations in summer, lower elevations in winter (Hornocker and Hash 1981, Whitman et al. 1986).Male home ranges large: up to 1,000 square kilometers (RIC 1999); averaging 422 square kilometers in Montana (Hornocker and Hash 1981) and 535 square kilometers in Alaska (Whitman et al. 1986). Home ranges of females with young much smaller, ranging from 73 to 416 square kilometers (Hornocker and Hash 1981, Gardner 1985, Magoun 1985, Whitman et al. 1986, Banci 1987, Copeland 1996).
Habitat
No habitat data have been reported for this species in Utah, and Durrant (1952) did not examine any specimens from this state. Although McKay (1991) did not provide any habitat information for the reported sightings of this species in Utah, the locational data suggest that the habitats have all been montane coniferous forest, as would be expected for this species. The report of the most recent sighting that has been received stated: "The wolverine was observed coming out of a clump of subalpine spruce [subalpine fir (Abies lasiocarpa)? or spruce (Picea sp.)?] and traveled south to the next clump, 50 to 150 meters away." The elevation of this site is 10,200 ft.
Food habits
Opportunistic. Feeds on a wide variety of roots, berries, small mammmals, birds' eggs and young, fledglings, and fish (Hatler 1989). 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 are captured by pursuit, ambush, digging out dens (Biosystems Analysis 1989), or climbing into trees. May cache prey in fork of tree branches or under snow.
Ecology
Solitary and wide ranging. Occurs at relatively low population densities (e.g., 1 per 65 sq km in one area in Montana). Males in some areas apparently are territorial, but in Montana there was extensive overlap of the ranges of both the same and opposite sexes. Apparently territory/range size depends on availability of denning sites and food supply (see Wilson 1982). Some individuals travel regularly over the same route (Wilson 1982). There are no important predators other than humans. See Whitman et al. (1986).
Reproductive characteristics
Breeds April-October (but variable), usually in summer. Implantation is delayed generally until winter. Gestation lasts 7-9 months; active gestation 30-40 days. One to six (usually 2-4) young are born January-April, mainly February or March (reportedly April-June in the Pacific states, Ingles 1965). Young are weaned beginning at about 7-8 weeks, separate from the mother in the fall. 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 12-15 months and produce their first litter when two years old. (Wilson 1982). In some areas, females may produce litters only every 2-3 years. In British Columbia, most mature females were reproductively active. Lives to an age of up to about 10 years, or sometimes 15-18 years or so.
Threats or limiting factors
In other states it has been shown that the presence of roads, such as logging roads, is negatively correlated with wolverine presence and populations. Even human presence and activity seem to be incompatible with wolverine populations. Timber harvest, forest fires, and other habitat alterations are clear threats to the species, as are, of course, direct human persecution, trapping, etc.
References
- Biotics Database. 2005. Utah Division of Wildlife Resources, NatureServe, and the network of Natural Heritage Programs and Conservation Data Centers.
- Burt, W. H. and R. P. Grossenheider. 1980. A field guide to the mammals. Houghton Mifflin Company, Boston. 289 pp.
