Wolverines in the lower 48 states warrant protection under the Endangered Species Act, but they are “precluded” from a listing because other species have a higher priority, the U.S. Fish and Wildlife Service announced Monday.

However, the agency’s “warranted but precluded” decision effectively reverses a 2008 determination made under the Bush administration that U.S. wolverines do not warrant federal protection because adjacent wolverine populations in Canada are healthy.

A coalition of environmental groups challenged that conclusion, noting that strong populations of grizzly bears and wolves in Canada have not influenced protection for those species in the United States.

“This decision finally reverses years of official denials that the wolverine faces a significant threat of extinction in the lower 48 states,” said Tim Preso, an attorney with Missoula-based Earthjustice. “Unfortunately, the decision still fails to give the wolverine the legal protections that it needs. We will continue to work to make sure that the wolverine remains a living, breathing part of our nation’s wildest landscapes.”

The U.S. Fish and Wildlife Service rated the wolverine as a 6 on a scale of one to 12 for species priority, with 1 being the highest-priority species.

“The threats to the wolverine are long term due to the impacts of climate change on their denning habitat, especially important to assist the species in successfully reproducing,” said Steve Guertin, director of the Fish and Wildlife Service’s Mountain-Prairie Region. “If we work with state and other partners to help the wolverine now, we may be able to counter the long-term impacts of climate change on their habitat and keep them from becoming endangered.”

Shawn Sartorious, a listing-recovery biologist with the agency’s Montana field office, explained that wolverines occupy the region’s coldest areas in alpine or subalpine habitat, and they particularly require persistent spring snow cover.

“The need for that snow relates to wolverine denning, which involves elaborate snow tunnels,” Sartorius said during a conference call on Monday.

Tunnels are used to protect against predators and shield young wolverines from extreme cold. Wolverines have very low reproductive rates, another factor in the determination that they warrant Endangered Species Act protection, Sartorius said.

Research carried out over the last few years in Glacier National Park’s Many Glacier Valley played into the decision for the wolverine to become a candidate species for protection. Disappearing and retreating glaciers have been well documented in Glacier Park over the last century.

Sartorius said it is believed that there are only about 200 wolverines remaining in the Northern Rockies, and only 10 in the Cascade Mountain Range. One is known to inhabit Colorado and there is one in California.

But Sartorious acknowledged that wolverine population estimates are based on “the best professional judgments” of biologists who are familiar with the species and the habitat they use.

“It’s a very difficult thing to determine populations for wolverines,” he said.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com.