Gulo gulo

Order: Carnivora
Order Description: Carnivores
Family: Mustelidae
Family Description: Weasels, Skunks and Others

The wolverine is the largest member of the weasel family. It measures up to a meter long, it has a shaggy appearance due to long (4 inch) guard hairs extending beyond its underfur. It is black to dark brown with white to yellowish brown on its chest that may extend as bands onto its sides and back to its tail. Its short tail also is shaggy appearing due to very long guard hairs on it. It somewhat resembles a bear cub in size, but it is longer and more squat. Total length is 28 to 42 inches (700-1050 mm), tail length is 7.2 to 10.4 inches (180-260 mm), and they weigh 30 to 60 pounds (14-27 kg).

The wolverine is found in remote wilderness from Labrador, east to Alaska, and south to mountainous regions of western United States.

It is found in alpine tundraClick word for definition and in borealClick word for definition and mountain forests. In California, it has been recorded at elevations of 1500 to 14,500 feet (480-4300 m). In Idaho, a 1985 survey indicated that the species inhabits remote, mountainous areas unaffected by human disturbance.

Like all members of the weasel family they are effective predators. Wolverines also can be classified as scavengers. They are famous historically as being very ferocious towards other animals and very effective at raiding trap lines in the far north. They are known to effectively prey on a variety of mammals including ground squirrels, beavers, porcupines, and even injured or sick elk and moose or those that might be hampered by deep snow. They also feed on a variety of roots, berries, small mammals, birds' eggs, fledglingsClick word for definition, and fish. However, small and medium-size rodents and carrion, especially ungulateClick word for definition carcasses, comprise a large percentage of diet.

Many folk tales and legends surround wolverines: they have been credited with extraordinary cunning, strength, savagery, and gluttony. Many of these tales come from the fur trapping era when wolverines did, in fact, raid trappers' cabins and steal bait and quarry from their trap lines. Like grizzly bears and wolves, wolverines symbolize wilderness. Idaho contains much wilderness and it appears to contain a population of wolverines. However, as humans have become more established in Alaska, Canada and remote areas of the Rocky Mountains, wolverine populations have declined. They are active throughout year, both day and night, but they are primarily nocturnalClick word for definition. When inactive, they occupy a den in a cave, rock crevice, under a fallen tree, or in a thicket. They are adept at climbing trees and swimming. They are solitary but range over vast areas. The mean annual home range of males has been reported at 535 km2 in Alaska, and 422 km2 in Montana; female's range has been reported at 105 km2 in Alaska, and 100 km2 in Montana. A male's home range typically overlaps the home range of more than one female. Another study with radiotelemetryClick word for definition determined annual home ranges for females and males to be 384 km2 and 1582 km2, respectively. Adult home ranges were segregated by sex. Male wolverines dispersed at sexual maturity at distances up to 185 km.

Breeding occurs from April through October, but is usually in summer. Wolverines are so sparsely distributed a problem for them may be finding a mate. This may account for the six plus month breeding period. After fertilizationClick word for definition occurs, implantationClick word for definition is delayed until January. Two to 5 young are born in late March to mid-April. In Idaho, females use high-elevation basins for natalClick word for definition sites.

Status: Protected nongame species
Global Rank: G4
State Rank: S2

Important State References:
Copeland, J.P. 1996. Biology of the wolverine in central Idaho. M.S Thesis, Univ. Idaho, Moscow. 138pp.

Information written by Donald Streubel, 2000
Photo from Yellowstone- National Park Service, Aug 2000.
Map image provided by Stephen Burton, 2000
Design by Ean Harker 1999, 2000, 2001.