Basic Facts About Wolverines

Called "skunk bear" by the Blackfeet Indians, the wolverine is the largest terrestrial member of the weasel family.

© Paul Nicklen / National Geographic Stock

The wolverine has a broad head, small eyes and short, rounded ears. It has glossy, dark brown fur, a light face mask and a stripe running down both sides of its body. The wolverine is powerfully built and has short legs with wide feet for traveling across the snow.

Diet

Wolverines are opportunistic feeders, and consume a variety of foods depending on availability. They primarily scavenge dead animals but are also very capable of killing their own meal, including ground squirrels and snowshoe hares.

Population

Based on occupied wolverine habitat, it is estimated that the wolverine population in the contiguous United States numbers fewer than 300 wolverines. Only 35 wolverines in the Rocky Mountains are estimated to be successfully contributing to the gene pool, which is an exceptionally low number.

Range

Wolverines live in rugged, remove country, spending most of their time in high elevations near or above timerline. Further north, wolverines occur within a wide variety of alpine, boreal and arctic habitats, including boreal forests, tundra and western mountains throughout Alaska and Canada.  

Historically, wolverine records in the lower 48 states show evidence of wolverine populations in the northern and southern Rocky Mountains, Sierra Nevada Mountains and North Cascades Mountains. They existed in the Great Lakes region prior to 1900, and in the Northeast and upper Midwest they were not likely present as a reproducing population after 1800.

Today, wolverines in the Lower 48 can be found in the North Cascades Mountains in Washington and the northern Rocky Mountains in Montana, Idaho and Wyoming (this area also includes the Wallowa Range in Oregon). There have been lone individuals found in the southern Rocky Mountains in Colorado and the Sierra Nevada Mountains in California.

Behavior

Wolverines do not hibernate, and are especially adapted for winter existence, with large paws like snowshows that allow them to stay on top of deep snow, and crampon-like claws that enable them to climb up and over steep cliffs and snow-covered peaks.

Wolverines are highly effective scavengers, with their keen sense of smell, strong teeth that crunch through bones, and their legendary ability to travel year-round through extreme alpine environments and over extraordinary distances. Wolverines have been documented traveling great distances, often going right over mountains instead of taking the easy way around. Individual wolverines may move more than 18 miles in one night. One male wolverine near Yellowstone traveled more than 500 miles in 42 days!

Wolverines are territorial animals and defend large, gender-exclusive territories. They naturally occur at low population densities. Yet, wolverines surprisingly have a social side. Male and female territories overlap each other, and they have strong family bonds. Even after they leave their mother, a male will still interact with his kits. 

Reproduction

Mating Season Breeding generally occurs from late spring to early fall. 
Gestation Egg implantation is delayed until the following winter or spring, followed by a 30-40-day gestation period
Litter Size Young wolverines are called kits. Litter size is one to five kits, with an average in North America of between one and two kits.
The females dig dens eight feet or deeper into the snow in the middle of winter, often in remote alpine cirques at or above treeline.