Scavenger Weasels Move a Step Toward State Reintroduction

The Cascades Carnivore Project shared this photo of a young male wolverine approximately one year old taken in the wild in Jan. 2022 at Mount Rainier National Park in Washington.
Kayla Shively/

Wildlife experts hope the encounter of one young male wolverine on the hunt for a new home range will change in a few years. They hope Colorado will once again become home to a viable breeding population of wolverines in high-Alpine areas. Trapping and poisoning wiped out the animals in the state some 100 years ago.

Experts believe less than 400 wolverines exist in the lower 48 states today.

“They are just this amazing Alpine species that we lost from Colorado,” said Stefan Ekernas, a wildlife biologist and director of field conservation for the Denver Zoo. “Ethically speaking, we killed the last wolverine, trapped and poisoned every last wolverine in Colorado, so it’s up to us to be the solution now and help the species come back.”

The wolverine is the largest land-dwelling member of the weasel family, and the solitary scavenger has a fierce reputation. Wolverines reach up to 35-40 pounds and live at high Alpine elevations primarily eating rodents and carrion.

Colorado Parks and Wildlife officials have worked on a wolverine reintroduction plan since 2010. Wolverines have long been a state-protected species, and in November, the North American wolverine received federal protection as a threatened species under the Endangered Species Act.

“Current and increasing impacts of climate change and associated habitat degradation and fragmentation are imperiling the North American wolverine,” according to the U.S. Fish and Wildlife Service.
The Cascades Carnivore Project shared this photo of a young male wolverine approximately one year old taken in the wild in January 2022 at Mount Rainier National Park in Washington.

On Friday, Colorado Senator Perry Will, a retired wildlife officer, planned to introduce a bill that would give Colorado Parks and Wildlife the authority to reintroduce wolverines into the state. In his Feb. 22 online newsletter, Will noted, “By introducing and hopefully passing this bill we can take the bull by the horns on this issue. The goal is to provide the legislature with oversight authority of the reintroduction to allow for more public participation in the process.”

“The species can have the greatest chance at a successful reintroduction when state and federal agencies work hand in hand with farmers and ranchers, ski industry, mining industry,” said Will, a Garfield County resident.

Wolverine experts and reintroduction modeling say high elevation areas in Routt County with extended snowpack into spring would be prime wolverine habitat. Females den very deep in the snow, so areas that hold snow longer are the best habitat. Ivan said the weasels have wide feet well suited to traveling on snow and live most of their lives above 10,000 feet.

Megan Mueller, who grew up in southern Routt County, now works as a conservation biologist for nonprofit Rocky Mountain Wild, a science-based organization working to conserve wildlife and wildlands in Colorado.   

“I spent a lot of time hiking and backcountry skiing in the Flat Tops and the Sawtooth Range, which have excellent habitat for wolverines, but I had to travel all the way to Denali National Park in Alaska to see a wolverine in the wild,” Mueller said. “It was one of the most amazing experiences of my life.”

“As the climate changes, Colorado’s high elevation mountains are expected to stay snowier and colder than other places where wolverines live,” Mueller explained.

Wolverines currently exist in the contiguous U.S. only as small populations in Idaho, Montana, Washington, Wyoming and northeast Oregon due to habitat loss, trapping and human disturbance, according to Rocky Mountain Wild.

Ivan said the closest breeding population to Routt County is in the Wind River Range in west-central Wyoming. However, since young female wolverines remain near the range of their mothers, females migrating to Colorado is very unlikely.

“The reason we need an active reintroduction is female wolverines are simply not going to disperse into Colorado,” Ekernas said.

Assuming the reintroduction process moves forward in Colorado, releasing wolverines likely trapped from Canada would not happen before 2026, Ivan said. The initial plan is to release 10 females and five males each year for three years in three high-elevation zones.

The Colorado Parks & Wildlife biologist said he is certain there is no viable population of wolverines in Colorado due to the extensive amount of wildlife research, surveys and baited game cameras, especially as the agency studies lynx that were reintroduced in 1999.

Experts say wolverine reintroduction is not expected to be controversial because of the solitary scavenging nature of the weasel, with only two documented cases of wolverine killing sheep in the past 100 years.

“There’s always fear about carnivores, but with wolverines, it’s more about the perception than what the reality will be,” Ekernas said. “Colorado has a long and rich history of reintroduction including river otter, Canadian lynx, bison, black-footed ferret and grey wolves. The last species remaining that we have not brought back is wolverines.”

This article was written by Suzie Romig for the Steamboat Pilot and was reposted by the Summit Daily.

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