Wolverines in the lower 48 states will received threatened status under the Endangered Species Act under a decision announced Wednesday/Cascades Carnivore Project

With climate change steadily eroding snowy habitat for wolverines in the lower 48 states, the U.S. Fish and Wildlife Service on Wednesday announced that it would list the cantankerous animal as threatened under the Endangered Species Act.

“The science is clear: snowpack-dependent species like the wolverine are facing an increasingly uncertain future under a warming climate,” said Michael Saul, Defenders of Wildlife Rockies and plains program director. “The protections that come with Endangered Species Act listing increase the chance that our children will continue to share the mountains with these elusive and fascinating carnivores. Now it’s time to support the species’ future by bringing them back to the mountains of Colorado as well.”

Wolverines, the largest land-dwelling members of the weasel family, once roamed across the northern tier of the United States and as far south as New Mexico in the Rockies and Southern California in the Sierra Nevada range. After more than a century of trapping and habitat loss, wolverines in the lower 48 today exist only as small, fragmented populations in Idaho, Montana, Washington, Wyoming and northeast Oregon.

In the wolverine’s last strongholds, the species is at direct risk from climate change. The animals depend on areas with deep snow through late spring. Pregnant females dig their dens into this snowpack to birth and raise their young. Snowpack is already in decline in the Western mountains, a trend that is predicted to worsen with a warming climate.

Wolverine populations are also at risk from traps, human disturbance, habitat fragmentation and extremely low population numbers resulting in low genetic diversity.

Wolverines have been spotted in Denali National Park, Yosemite National Park, Yellowstone National Park, Mount Rainier National Park, Grand Teton National Park, Glacier National Park, and North Cascades National Park, among others. It's difficult to say just how many wolverines are wandering around the parks. Their extensive travels, sneaky scavenger-like maneuvering, and solo dwelling make it difficult for researchers to closely monitor their patterns.

Wednesday's announcement represented a 180-degree reversal by the Fish and Wildlife Service, which in October 2020 had declined to extend threatened status under the ESA to the small but fierce carnivore, saying wolverine populations were doing fine. 

Part of that decision was based on a 2018 "Species Status Assessment" that noted that "wolverine appears resilient within its contiguous United States range." The assessment pegged the wolverine population in the country at 318, with potential habitat to support 644 individuals. Canada, meanwhile, claims thousands of wolverines, according to the assessment.

That decision was challenged in December 2020 by conservation organizations that maintain there are fewer than 300 wolverines left in the contiguous United States, and that listing wolverines as threatened or endangered would trigger new, badly needed conservation efforts. In May 2022 U.S. District Judge Donald Molloy agreed with the organizations and gave the wildlife agency 18 months to determine whether wolverines deserved to be relisted.

In September the Service updated its 2018 species status assessment for the North American wolverine with an addendum that reflects new information since 2018. The addendum evaluated updated information on climate change, habitat connectivity, trapping, snow, population density, and impacts on genetic diversity, as well as considered changes in regulatory mechanisms and conservation measures.

"Current and increasing impacts of climate change and associated habitat degradation and fragmentation are imperiling the North American wolverine,” Fish and Wildlife Sdrvice Pacific Regional Director Hugh Morrison said in announcing the listing decision. “Based on the best available science, this listing determination will help to stem the long-term impact and enhance the viability of wolverines in the contiguous United States.”

Timothy Preso, an Earthjustice attorney who represented conservation groups in the long-running legal campaign to protect the wolverine, said the decision "gives the wolverine a fighting chance at survival. There is now hope for this icon of our remaining wilderness.” 

The proposed and final rules and the comments received on the proposed rule are available at http://www.regulations.gov in Docket No. FWS-R6-ES-2012-0107.

The Service requests comments or information from other concerned federal and state agencies, Tribes, the scientific community, or any interested party concerning the interim 4(d) rule. A 60-day comment period begins Nov. 30, 2023 and comments must be received by Jan. 29, 2024. The proposal and information on how to submit comments can be found at http://www.regulations.gov/ by searching under docket number FWS–R6–ES–2012–0107.