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American wolverine
Candidate Project
The Denver Post, December 14, 2010

Wolverines merit endangered species protection, but must wait
By Howard Pankratz

The U.S. Fish & Wildlife Service announced Monday that the wolverine warrants protection under the Endangered Species Act, but the listing will be delayed because other species take higher priority.

Wolverines, who are members of the weasel family, are only a candidate for listing, and their status will be reviewed annually, the agency said.

Reasons for protection include destruction, modification and curtailment of its habitat and range by climate change.

Shawn Sartorius, a Fish & Wildlife Service biologist, said the effect of climate change is the biggest threat to the wolverine population in the contiguous U.S., and it will probably be irreversible within the foreseeable future.

Sartorius noted that deep snow is required for successful wolverine reproduction because female wolverines dig elaborate dens in the snow for their offspring. The den structures protect wolverine kits from predators and harsh alpine winters.

Predictions by the University of Washington Climate Impacts Group and the U.S. Forest Service Rocky Mountain Research Station show a reduction of their cold and snowy habitat of 63 percent by 2099.

However, Sartorius said the number of wolverines in the lower 48 states — 212 — is the highest it has been in 100 years.

Sartorius said it appears wolverines in the lower 48 have expanded to the point where they may be close to peaking in numbers. They need an arctic or sub-arctic climate, which can only be found now in the highest mountains, he said.

The fact that wolverines were not listed immediately upset numerous conservation groups.

"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, a lawyer for Earthjustice, a nonprofit law firm that fights for protection of wildlife and natural resources. "Unfortunately, the decision still fails to give the wolverine the legal protection it needs."

A coalition of conservation groups — including Defenders of Wildlife, Conservation Northwest, the Center for Biological Diversity and Earthjustice — said a recent study found that just 35 individual wolverines are breeding successfully in the lower 48 states.

"Important and powerful new research techniques show that wolverines need reliable snowpack and that consistently snowy areas are declining and increasingly isolated in the western United States," said Dave Gaillard, the Rocky Mountain representative for Defenders of Wildlife. "Similar to the polar bear, the wolverine needs our immediate help to compensate for this significant decline in their effective range."

The Fish & Wildlife Service said the wolverine wouldn't be immediately listed because its primary threat — global warming — is not imminent.

A young wolverine made history this year when it traveled more than 500 miles from Grand Teton National Park in Wyoming into Colorado, the first sighting of a wolverine in the Centennial State since 1919.

The Fish & Wildlife report noted that the wolverine is listed as endangered by the states of Colorado, Washington and California. In Idaho and Wyoming, it is designated as a protected nongame species.

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Photo © Paul S. Hamilton