As Colorado Parks and Wildlife maps out wolf reintroduction, the agency is considering how to support wolverines, revisiting a stalled plan to reintroduce the rare carnivore in the state.
The last time wildlife officials confirmed a wolverine in Colorado was June 2009, when a male – tagged with a radio collar in Grand Teton National Park in Wyoming and known as M56 – wandered south to Rocky Mountain National Park and even into the Collegiate Peaks outside Leadville.
M56 roamed – as wolverines are wont to do – and eventually reached North Dakota in 2016, where he was shot by a ranch hand guarding his cows. That was the first confirmed wolverine in North Dakota since 1889. (And wolverines, while opportunistic eaters, have not been known to hunt cattle.)
Before M56 ambled into Colorado, the last confirmed sighting in the state was 1919. A dozen surveys by Colorado biologists from 1979 to 1996 yielded no evidence of wolverines. (There have been unconfirmed sightings in southern Colorado, which means there could be “a small but persistent number of individual wolverines” in the Rio Grande National Forest and the southern San Juan Mountains, according to a 2003 survey by the Rio Grande National Forest.)
Wolverines in the Yellowstone Region claim a home range as large as 500 square miles. Females roam a range about half that size. The elusive carnivores – the stoutest of the weasel family that includes otters and martins – can traverse nearly 20 miles of alpine terrain and deep snow in a single day. Researchers estimate there are between 250 and 625 wolverines in the Lower 48.
They are peculiar animals. Males claim ranges that span hundreds of miles. Somehow they know not to occupy each other’s home areas, so young males often wander hundreds of miles to find unclaimed territory. But how can they know that a remote mountain range has been staked by another wolverine?
“You got me,” said Jeff Copeland, a 20-year wolverine researcher with the Wolverine Foundation. “They develop a wanderlust about reproduction maturity, around two years of age, and they just end up in the darndest places.”
Trappers nearly eradicated wolverines in the early 1900s. In 2013, the U.S. Fish and Wildlife Service proposed protecting wolverines under the Endangered Species Act, which would have established “an experimental nonessential population” of wolverines in southern Colorado. The service withdrew the proposal in 2014 and a consortium of wildlife groups sued the federal government.
The groups won their case and the Fish and Wildlife Service launched a new study – a species status assessment completed in 2018 – that included how a warming climate and melting snow might impact the wolverine. Females can burrow 10 feet into alpine snow fields for denning. The 2018 study acknowledged climate change as a “significant stressor” on wolverines but concluded that snow will persist at higher elevations through 2055.
In 2020, the Fish and Wildlife Service again declined to protect wolverines under the Endangered Species Act.
“The cumulative effects of wildland fire and climate change (e.g., snowpack) will continue to represent a low impact to the wolverine and its habitat into the mid-21st century, based on climate change projections,” the agency’s 2020 decision reads.
Colorado does consider the wolverine an endangered species.
Colorado first gentleman Marlon Reis last month posted on Facebook his support for reintroducing wolverines to Colorado, noting that Colorado Parks and Wildlife was “in discussion with partners and stakeholders” about the return of the rare mammal.
Wolverine reintroduction has not come up in Colorado Wildlife Commission meetings for more than a decade. The agency began a wolverine reintroduction process in 2010 and created “an extensive plan for how reintroduction could be accomplished,” said CPW spokesman Travis Duncan.
Recently, the agency has been reviewing that plan and process to find possible updates and what remains workable, Duncan said.
“We will be working with a wolverine expert who is going to take on updating and providing greater detail on a wolverine restoration and management plan,” he said. “The contract isn’t in place yet, but we hope to be able to say more on this soon.”
CPW Director Dan Prenzlow kicked off his agency’s first Colorado Outdoors podcast in October 2020 with a discussion about restoring species in the state. Just about all the wildlife in the state – including deer, elk, bighorn sheep, river otters, turkeys and cutthroat trout – were reintroduced with support from the wildlife agency, he said.
“We are having robust discussions about wolverines in the state,” he said. “We are interested in restoring wolverines at some level.”
Wildlife commissioner Jay Tuchton supports wolverine reintroduction as well. He was an attorney with wildlife groups that urged wolverine reintroduction in 2010, which led the state to draft the plan.
“We are at that preliminary stage of dusting off the process from 2010 and working through what needs revision, updates, etc. before anything more formal is underway,” CPW spokeswoman Rebecca Farrell said in an email.
Copeland does not support reintroduction of the species. “It’s a last-resort kind of approach.”
Relocating animals usually kills about half of the transplanted animals, Copeland said. That’s fine for elk deer, pronghorn and bighorn sheep, he said.
“But when you are dealing with a very rare animal like a wolverine, there is no room for error and there are not any surplus animals anywhere in the world,” Copeland said.
Montana allowed wolverine trapping in the early 2000s and that limited the numbers of wolverines that were roaming south. When Montana stopped trapping in 2012, researchers started to see more young wolverines venturing south, Copeland said.
Wolverines have been working to reoccupy their historical range across the Southern Rockies since the 1960s and the animals are making progress. Slowly, but it’s happening, Copeland said.
“They are doing it on their own. It’s a historic moment. Why don’t we just watch it happen?” Copeland said. “They will reoccupy Colorado and they will be in Utah and there is every reason to believe they will survive on their own. So why spend millions of dollars and kill a dozen wolverines just because we want them there now? It may take 40, 50 years, but so what?”