The U.S. Fish and Wildlife Service announced Wednesday it will list wolverines as a threatened species, citing future global warming as the main threat to the snow-loving carnivore in Washington, Idaho, Montana and Wyoming.

Wolverines den in deep spring snowpacks. To date, the wildlife service said it sees no sign that climate change has hurt the estimated 300 wolverines in the Northern Rockies and the North Cascade Range.

Climate prediction

Climate models, however, predict that by 2100 spring snowpacks will diminish by 10% to 50% at the altitudes wolverines den, according to the agency.

The loss of snow will make it harder for wolverines to overcome other threats such as low reproductive rates, an intolerance for humans and potential inbreeding, the agency stated.

“Current and increasing impacts of climate change and associated habitat degradation and fragmentation are imperiling the North American wolverine,” Pacific Regional Director Hugh Morrison said in a statement.

Wolverines need cold storage

The wildlife service has contemplated listing wolverines as a threatened species for a decade. The agency in 2020 concluded wolverines would have ample snowpack in 2055.

The agency recently changed its viewpoint, extending its snowpack outlook to the end of the century. The agency also changed its standard for adequate spring snow depth from 20 inches to 39 inches.

Wolves stash perishable food in snow year-round. Higher temperatures could spoil food or lead to pilfering by other animals, according to the agency. 

Environmental groups campaigned to give wolverines the protection of the Endangered Species Act, filing suits in federal court to prod the wildlife service.

“We’re happy the species is finally getting the protection it needs,” Center for Biological Diversity carnivore conservation legal director Andrea Zaccardi said.

The wildlife service has not yet done a study on the economic consequences of listing wolverines.

Although wolverines inhabit high altitudes between tree lines and ice-capped peaks, they travel through connecting valleys, potentially affecting logging and mining at lower altitudes, Zaccardi said.

Wolverines get around

The wildlife service describes wolverines as looking like a small bear with a bushy tail. It’s the largest member in a family of species that includes the weasel and mink.

Alaska has thousands of wolverines. Fish and Wildlife’s announcement applies to wolverines in the Lower 48.

Unregulated trapping and predator control in the late 1800s and early 1900s extirpated wolverines, according to Fish and Wildlife. Wolverines returned to the U.S. by migrating from Canada.

Only Washington, Idaho, Montana and Wyoming are known to have wolverines breeding within their borders. Wolverines have occasionally been spotted in Oregon, California, Colorado and Utah.

Washington has an estimated 50 wolverines isolated from Rocky Mountain wolverines, according to Fish and Wildlife. Wolverines have recently bred in Mount Rainier National Park.

A wolverine, presumably a lone disperser, was seen on the Long Beach Peninsula in 2021 feeding on an elephant seal carcass more than 90 miles from the nearest known occupied habitat.

The wildlife service said it knows of two cases of wolverines attacking farm animals in the past five years. Both attacks occurred outside where wolverines are normally found.

A wolverine was caught in a chicken coop in Klickitat County in south-central Washington and was shot and killed by the landowner.

A wolverine attacking sheep in Utah was trapped and released into the Uinta Mountains in northeast Utah.