Feds propose threatened listing for wolverine

A wolverine in snow. Photo courtesy USFWS/Steve Kroschel.

Nonessential, experimental designation could help restoration effort in Colorado

By Bob Berwyn

SUMMIT COUNTY — North American wolverines may get some help facing the threat of global warming, as the U.S. Fish and Wildlife Service this week proposed listing the omnivorous mammal as a threatened species, while designating a nonessential experimental population of the animals in the southern Rockies, including Wyoming, Colorado and New Mexico.

The designation provides for allowable legal incidental taking of the wolverine within the defined nonessential population area and opens the door for a possible state-led reintroduction effort in Colorado. Under this designation, current land uses could generally continue unchanged if wolverines are reintroduced to Colorado in the future.

The announcement triggers a public comment period, as the agency seeks to shape a final version of the listing, taking input on any other potential threats faced by wolverines, and how the listing may affect human activities. Federal biologists aid they’d also consider whether reintroductions should be considered in other areas, including the Sierra Nevada of California. The formal proposal, along with public comment information, is HERE.

“Wolverines naturally live in small populations over large areas, and the predicted loss of spring snow due to climate change makes them vulnerable to population decline,” said Jason Wilmot, executive director and wolverine researcher with Northern Rockies Conservation Cooperative, a research based conservation organization in Jackson, Wyoming.

Female wolverines require deep snow that persists through mid-spring for raising their young, but wolverines may lose up to two-thirds of suitable habitat by the end of this century. Researchers estimate that the extent of areas in the western U.S. with persistent spring snowpack is likely to recede 33 percent by 2045 and 63 percent by 2099 as a result of climate change.

“Colorado could serve as an important refuge for the species because the high elevation and rugged terrain may remain cold and snow-covered longer than other areas in their range.If wolverines lived in the large amount of high quality habitat in Colorado, the overall wolverine population in the lower 48-states stands a much better chance of lasting long into the future,” Wilmot said.

“One of the most important things that we can do to ensure the survival of wolverines in the West in the face of climate change is to get them back on the ground in Colorado,” said Megan Mueller, senior conservation biologist with Rocky Mountain Wild, a Denver-based conservation organization. “Ideally, we’d like to see wolverines reintroduced with the full protections of the Endangered Species Act. However, we are hopeful that the experimental designation is a compromise that will make it possible for everyone to support reintroduction of wolverines to Colorado.”

The species historically lived in the remote, high-elevation areas of Colorado until the early 1900s when they are thought to have been eliminated from the region by poisoning and trapping. In the spring of 2009, researchers in northwest Wyoming tracked M56, a lone male wolverine, as he traveled 500 miles from near Grand Teton National Park into north central Colorado. He is thought to be the region’s first wolverine in over 90 years.

Based partly on experience gained during a decade-long lynx recovery effort, Colorado wildlife biologists developed a draft wolverine restoration plan and engaged with a group of stakeholders to broach the idea. The talks were paused while the U.S. Fish and Wildlife Service was considering its listing decision.

According to federal biologists, wolverines appear to be distributed in two regions in the lower 48 states: the northern Cascades in Washington, and the northern Rocky Mountains in Idaho, Montana, and Wyoming.  Wolverines were extirpated in historical times from the Sierra Nevada and the southern Rocky Mountains.

Experts say it’s challenging to determine present and historical populations because wolverines  live in remote and inhospitable places away from human populations, at low densities. Encounters are rare and unpredictable, making it difficult to determine their present range, or trends in range expansion or contraction that may have occurred in the past.


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