Wolverine

Wolverines 101

The wolverine is the largest land-based member of the weasel family and roams the most rugged and beautiful areas of the Rocky Mountains and North Cascades in the western United States. These animals are also exceedingly rare, with scientists speculating that fewer than 300 wolverines may live in the U.S., possibly fewer. Only 35 wolverines are estimated to successfully breed in the Rocky Mountains—a critically low number.

Why They’re Important

Wolverines are primarily scavengers, feeding off old or sick animals that die in the cold. But they can also take down much larger animals, even elk and moose under the right circumstances such as extreme snow. Wolverines are a vital part of the ecosystem in their own right, but also a great ambassador of the wild places they inhabit.

Major Threats

Wolverines rely on deep spring snow to rear their young, so they are especially vulnerable to the loss of their alpine habitat due to climate change. Scientists predict that wolverines in the lower 48 states may lose two-thirds of their suitable, snow-covered habitat by the end of the century.

They are also threatened by trapping and possibly from human disturbances from winter recreation activities. Given the low numbers of wolverines, each of these threats can have a major impact on wolverine recovery.

What Defenders Is Doing to Help Wolverines

Defenders of Wildlife has been fighting to protect wolverines under the Endangered Species Act since 2000. After pressure from Defenders and other conservation groups, the U.S. Fish and Wildlife Service has proposed to list the wolverine as a threatened species, and will make a final determination by early 2014. Defenders is advocating for a listing, along with decisive action that will help secure the future of the species. 

We’ve also recruited and trained volunteer “citizen scientists” to document wolverines using snow-tracking and remote cameras. We reach out to backcountry enthusiasts in the West to document information whenever they see wolverines or their tracks - this provides scientists with important information about the location of wolverines in the wild. 

More on Wolverine: Background and Recovery »

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In the Magazine
Scientists estimate only about 250 to 300 of these bear-cub-sized hunter-scavengers now roam the lower 48 states, primarily in increasingly isolated mountain strongholds in Idaho, Montana (which still allows trapping), Oregon, Washington and Wyoming.
Conservation Issue
Climate change is now one of the leading threats to wildlife. Find out what Defenders is doing to help animals around the country survive in a warming planet.
Fact Sheet
Called "skunk bear" by the Blackfeet Indians, the wolverine is the largest terrestrial member of the weasel family. It has a broad head, small eyes and short rounded ears.