GREEN RIVER -- What's small with big feet, has great ferocity and cunning, lives mostly out of sight in Canada, and is soon to be the subject of a federal lawsuit?

Federal scientists know it's the reclusive wolverine, the fierce, furry scavenger that roams parts of western and northwest Wyoming, Idaho and Montana as well as Canada.

Last March, U.S. Fish and Wildlife Service officials decided the wolverine did not warrant federal protection under the Endangered Species Act.

On Tuesday, a coalition of 10 conservation groups announced its intention to file a legal challenge within 60 days against the agency that will seek to overturn the decision.

The groups contend the Fish and Wildlife Service violated the terms of the Endangered Species Act when it refused to protect wolverines in the United States -- just because a healthy population still persists in Canada.

The decision "is essentially outsourcing responsibility for our wildlife to other countries," said David Gaillard, the Rocky Mountain region representative for Defenders of Wildlife.

"With global warming compounding the many threats facing snow-dependent wolverines, protections are needed more than ever to ensure that this magnificent animal continues to call the U.S. home," Gaillard said in a release with Earthjustice, the Center for Biological Diversity, and other conservation groups involved in the lawsuit.

Those groups include the Greater Yellowstone Coalition, the Jackson Hole Conservation Alliance and the Wyoming Outdoor Council.

The largest of the weasel family, the wolverine -- once described as a weasel with a scrap of demonic fury -- is a scavenger that is found in the highest elevations of Wyoming's Rocky Mountains, including the Gros Ventre and Absaroka mountains.

The animal is also found in parts of Alaska and Canada and some parts of the midwestern United States. Scientists say the animal lives in just a fraction of its historical range.

Conservationists have been battling the Fish and Wildlife Service over a possible endangered listing for the wolverine for nearly a decade.

Wolverine advocates contend populations are in steep, drastic decline and need help. Problems for the species include loss of habitat because of roads and other human development, trapping in Montana, and denning disturbances caused by snowmobiles.

In response to a court ruling in 2006, the Fish and Wildlife Service conducted a "status review" to determine whether the species warranted further protection as a threatened or endangered species. Agency officials said in the final review document released in March that the wolverine did not warrant that protection.

The agency said the wolverine population in the United States is "not discrete, because it is not separated from wolverine populations in Canada, and is likely dependent on them to some degree to maintain genetic diversity."

But Tim Preso, an attorney with Earthjustice, said the wolverine warrants federal protection in part because the animal is especially vulnerable to the effects of global warming, as it depends on deep snow habitat to survive.

"We will do everything we can to reverse this stunning ... interpretation of the law," he said.

The wolverine is the largest terrestrial mammal in the weasel family. The large-footed animal grows to about 25 pounds and more than three feet in length, according to Wyoming Game and Fish Department biologists.

Small populations of the wolverine can be found in the mountains of extreme western and northwestern Wyoming. The animal ranges from the high Teton Mountains near Jackson to the low, sagebrush mule deer winter range near Kemmerer and Cokeville.

While little research has been done on wolverines in Wyoming, there have been several wolverine sightings in recent years, including sightings along State Highway 30 near Kemmerer, in Buffalo and north of Cheyenne.

Southwest Wyoming bureau reporter Jeff Gearino can be reached at 307-875-5359 or at gearino@tribcsp.com.