BILLINGS, Mont. — A top federal wildlife official said there's too much uncertainty about climate change to prove it threatens the snow-loving wolverine — overruling agency scientists who warned of impending habitat loss for the so-called "mountain devil."
There's no doubt that the high-elevation range of wolverines is getting warmer, U.S. Fish and Wildlife Service Regional Director Noreen Walsh said.
But any assumption about how that will change snowfall patterns is "speculation," Walsh said. She told her staff to prepare to withdraw a proposal to protect the animals under the Endangered Species Act.
Walsh's comments were contained in a May 30 memo obtained by the Center for Biological Diversity, an environmental group. Fish and Wildlife Service spokesman Chris Tollefson confirmed that Walsh — who heads the agency's mountain-prairie region — authored the document.
Agency Director Dan Ashe will have the final say, with a decision due Aug. 4.
The animals max out at 40 pounds and are tough enough to stand up to grizzly bears. Yet some scientists warn that they will be no match for anticipated declines in deep mountain snows, which female wolverines need to establish dens and raise their young.
Federal biologists last year proposed protections for an estimated 300 wolverines in the Lower 48 states. At that time, Walsh said "scientific evidence suggests that a warming climate will greatly reduce the wolverine's snowpack habitat."
In the recent memo, she expressed the opposite view: "Due to the uncertainty of climate models, I cannot accept the conclusion about wolverine habitat loss that forms the basis of our recommendation to list the species."
Walsh, also a biologist, said she reached that conclusion after reviewing the latest science on wolverines and consulting with other agency officials.
But most of that science already was available when protections were first proposed, leading Noah Greenwald of the Center for Biological Diversity to criticize the about-face. He said the likelihood of climate change harming wolverines was too great to delay action because of any lingering uncertainties.
"There is no reason to think they are going to be OK," Greenwald said.
Fish and Wildlife Service officials say Walsh's memo was just one step in the agency's deliberations over wolverines.
Once found throughout the Rocky Mountains and in California's Sierra Nevada mountain range, wolverines were wiped out across most of the U.S. by the 1930s due to unregulated trapping and poisoning campaigns. In the decades since, they have largely recovered in the Northern Rockies but not in other parts of their historical range.
In some areas, such as central Idaho, researchers have said suitable habitat could disappear entirely.
Wolverines are found in the North Cascades in Washington and the Northern Rocky Mountains in Idaho, Montana, Oregon and Wyoming. Individual wolverines have also moved into California and Colorado but have not established breeding populations.
Larger populations persist in Alaska and Canada.
Officials from Western states including Montana, Wyoming, Utah and Idaho had objected to more protections and said the animal's population has been increasing in some areas.Comment on this story
Two members of an independent peer review panel also raised questions about the science behind last year's proposal. They suggested that no direct link could be made between warming temperatures and less habitat.
Panelist Audrey Magoun, a researcher based in Alaska, said shifting weather patterns that come with a warming climate could mean more snowfall, not less, in the mountains where most wolverines den.
Wolverines were twice denied protections under the Bush administration. In 2010, the Obama administration delayed action on the issue and said other imperiled animals and plants had priority over wolverines.