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Wolverine Returns to Colorado After 90 Years

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Photo of wolverine courtesy National Parks Service

A wolverine that Wildlife Conservation Society researchers have been tracking since early April has crossed into northern Colorado–the first known incidence of a wolverine in the state since 1919, the New York-based conservation charity said this week.

“The wolverine, a young male labeled M56, [that] was captured near Grand Teton National Park … traveled approximately 500 miles during April and May, successfully navigating significant man-made features, including Interstate 80–the heavily trafficked route across Wyoming that links Chicago, Salt Lake City and San Francisco,” WCS said.

Researchers placed a radio-tracking collar on the wolverine as part of an ongoing study to understand the wide-ranging, little-known animals.

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Wolverines are the largest land-dwelling members of the weasel family. They live in arctic habitats in Alaska and Canada, and range south into the lower 48 states only high in mountains where near-arctic conditions exist.

“A growing body of research is showing that wolverines need large areas to survive and that the young often disperse long distances between mountain ranges to find a territory and mates,” WCS said in a statement.

“Even though adult wolverines average about 30 pounds, a home range is often as large as a grizzly bear’s.

“The size of a wolverine’s territory, as much as 500 square miles for some adult males, limits the number of individuals that a given area can support. Adults tend to inhabit areas above timberline where there are snow-covered avalanche chutes and freezing temperatures much of the year.”

Iron Men of the Animal Kingdom

“Wolverines are the real ‘iron men’ of the animal kingdom, traveling seemingly nonstop in some of the most rugged country in North America,” said Robert Inman, director of WCS’s Greater Yellowstone Wolverine Program.  “It is great news that this animal has ventured into Colorado, where it hasn’t been documented in 90 years, but it also underscores the need to manage this species at a multi-state, landscape scale.”

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Photo courtesy WCS

The Greater Yellowstone Wolverine Program is a public-private partnership between the Wildlife Conservation Society, the state game departments in Wyoming, Idaho and Montana, Grand Teton National Park, and the Bridger-Teton, Caribou-Targhee, Beaverhead-Deerlodge, and Gallatin National Forests.

The state, federal, and private partnership represents the longest ongoing study of wolverines in North America, and has focused its field-based research on documenting the species-specific biology necessary to develop successful management strategies in the lower 48 U.S. states, WCS added. 

“The partnership has been able to increase research capacity of the governing agencies by combining resources from private sources together with the limited public funding available to learn about wolverines,” said Mark Orme, a biologist for the Caribou-Targhee National Forest. 

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Photo of wolverine and cubs courtesy WCS

The wolverine was once native to the mountainous areas of Washington, Idaho, Montana, Wyoming, Utah, Colorado, and California. Records indicate that populations were nearly wiped out by about 1930, according to WCS. “Recovery has occurred to some degree during the previous 80 years. However, vast areas of suitable habitat on public lands in California, Utah and Colorado do not appear to have breeding populations at present.”

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Map showing how wolverine was tracked into Colorado courtesy WCS

The Colorado Division of Wildlife (CDOW) is working with WCS to track the wolverine in order to monitor its movements and activities. “At this time the CDOW has no plans for either wolverine reintroduction or surveys,” the WCS statement said. “Future considerations for wolverine management in Colorado would have to involve members of the public and would be guided by direction from the Colorado Wildlife Commission.”

Something of an Anomaly

“This is certainly an interesting event and could give us some initial information on wolverines in Colorado,” said Rick Kahn, Terrestrial Section Manager for the CDOW.  “But the occurrence of a single animal needs to be treated as somewhat of an anomaly.”

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Image courtesy WCS

In 2008 and again in 2009, a lone male wolverine thought to be from a Rocky Mountain population was photographed by a remote-controlled camera in Tahoe National Forest of northern California.

“The single instances of male wolverines being documented in California during 2008 and now Colorado are encouraging,” said Shawn Sartorius of the U.S. Fish and Wildlife Service.  “But it remains to be seen if females can make similar movements that would be required to establish populations.” 

The dispersal of young wolverines from one mountain range to another where there are unrelated individuals is essential, according to WCS. “One of the reasons the researchers were tracking M56 was to understand which habitat features wolverines key-in on while dispersing across arid valley bottoms, many of which are under increasing pressure to be converted from ranchland to subdivision. Ultimately these data will help identify migration corridors and other habitats important for wolverine conservation.”

“A glimpse of one … becomes a moment that is not forgotten.”

“As a state with a source population of wolverine, Montana has adjusted wolverine management to be in line with these landscape-scale, multi-state objectives,” commented Brian Giddings with Montana Fish, Wildlife and Parks. “If we had the opportunity to make further progress toward collaborative wolverine management at this large scale, I could see using our sportsmen to help live-capture and restore the species to some of its former range. Then they could be part of a historical achievement for wildlife conservation in the U.S.” 

said Robert Inman, director of WCS’s Greater Yellowstone Wolverine Program,”The great thing about wolverines is that almost everyone finds them interesting. They live in such rugged terrain and are so elusive that even the most weathered outdoorsmen have rarely caught a glimpse of one.

“When they do, it becomes a moment that is not forgotten.”