Climate change is melting the snowpack that wolverines need for denning, which along with other issues has left the species on the "precipice of extinction in the contiguous United States," the groups said in their notice of intent to sue, sent to Interior Secretary Dirk Kempthorne and U.S. Fish and Wildlife Service Director H. Dale Hall.
Wolverines, which resemble small bears, are in the weasel family and are rarely seen. The Fish and Wildlife Service has estimated the U.S. wolverine population outside of Alaska consists of about 500 animals in Montana, Idaho, Washington and Wyoming. The environmental groups believe fewer animals exist.
The service said in March that even if they disappeared from the lower 48 states, wolverines would survive because those in the United States are connected to larger populations in Canada. There, the number of wolverines has been estimated at 15,000 to 19,000.
The environmental groups say wolverines in the United States and those in Canada are genetically separate. That is disputed by the Fish and Wildlife Service.
Agency spokeswoman Diane Katzenberger said Tuesday that officials had not seen the notice of intent to sue and have a policy of not commenting on pending litigation.
She said an analysis of threats to wolverines did not support Endangered Species Act protection.
"The finding was that the U.S. population does not significantly contribute to the overall viability of the North American population," Katzenberger said.
Many wolverines were killed during an early 20th century poisoning campaign against wolves and other large predators in the United States.
Threats to wolverines today include helicopter skiing, unregulated use of snowmobiles, and trapping in Montana, the only state besides Alaska that allows trapping, the groups said.
They include the Center for Biological Diversity, Conservation Northwest, Friends of the Clearwater, Greater Yellowstone Coalition, Idaho Conservation League, Jackson Hole Conservation Alliance, Klamath-Siskiyou Wildlands Alliance and Wyoming Outdoor Council.
