The population of wolverines in the contiguous United States has rebounded to an estimated 250 to 300 since the early 20th century, when predator control in the West nearly wiped them out, the U.S. Fish and Wildlife Service said in its report.
But their resurgence may be short-lived.
Wolverines need adequate spring snow cover to reproduce, but warmer winter temperatures are reducing the snow pack in the West, making climate change the "primary threat to the wolverine population," the report said.
Environmental models project the wolverines' habitat will shrink by roughly a quarter by 2045 and nearly two-thirds by 2099, agency wildlife biologist Shawn Sartorius said.
That means the animals will not be added to the federal Lists of Endangered and Threatened Wildlife and Plants. Instead, it will join the sage grouse, plains bison and hundreds of other species on a candidate species list awaiting federal protection.
The length of time the wolverine remains on the candidate list depends on the species ahead of it and when funding would be available to add it to the endangered and threatened species list, Fish and Wildlife Service spokeswoman Diane Katzenberger said.
The wolverine is one of a handful species the federal government says needs protection because of the effects of climate change on habitat. Most recently, the National Oceanic and Atmospheric Administration cited the loss of ice from climate change as a basis for proposing that ringed and bearded seals be listed as a threatened species.
Conservation groups petitioned the federal government to protect the wolverine in 1995 and again in 2000. Two years ago, the agency found the wolverine was not eligible for listing under the federal Endangered Species Act because it did not constitute a distinct population segment.
Conservationists sued, and last year the agency agreed to study the matter again. This time, the agency found the population within the contiguous U.S. was distinct and warranted protection.
Tim Preso, an attorney with Earthjustice, told The Associated Press the new finding is a breakthrough that reverses past denials by the federal government that the wolverine faces the threat of extinction.
However, the wolverine will now be mired in a backlog of other species waiting to receive federal protection, he said.
"If history is any guide, it takes a very long time for any action to be taken on this backlog," Preso said. "It's like being stuck in the waiting room of a hospital when you're in need of care."
Wolverines likely exist as a network of semi-isolated populations, and they require gene flow between groups to support each other and prevent individual populations from going extinct. If that dynamic breaks down, the entire population could be jeopardized, the Fish and Wildlife Service said.
Global warming will threaten that breakdown, the agency said.
The reduced snow pack means the cover suitable for wolverines is shrinking, and the distance between the semi-isolated populations is growing, making it more difficult for the wolverine groups to exchange genes, the report states.
The wolverine has a broader range in Canada and Alaska, territory separate from the newly designated distinct population segment in Montana, Idaho, Washington, Wyoming, Colorado, Oregon, Utah and California.
In Canada, wolverines are considered endangered in the eastern part of the country and a species of special concern in the western part of the nation.