When Hugh Jackman agreed to play the mutant superhero Wolverine in the X-Men franchise, he didn’t know that wolverines were real.He thought he was playing a wolf. At a loss for how to mimic a wild canine, he watched a documentary on wolves to better understand how they moved and acted, arriving on set with a “funny” gait. He recalled the ridicule of his director Bryan Singer in an interview with Page Six in 2017: “He said, ‘You know you’re not a wolf, right? ... Go to the zoo, dude.’ I literally didn’t know [wolverines] existed.”
Colorado wants to bring back the wolverine. There’s just one problem.
Should we help wild animals get to better habitats to survive?
Mary Kirkpatrick for Vox
Christine Peterson is a freelance journalist who covers science, the environment, wildlife, and the outdoors. She is based in Laramie, Wyoming.
The famous actor isn’t alone in this oversight. Wolverine biologist Rebecca Watters has gotten used to people thinking wolverines are deep fakes or mythological creatures. She’s spent more than a decade explaining to a sometimes bewildered public that wolverines are not another name for wolves (which exist) or werewolves (which don’t).
“People just don’t know what the animal is,” Watters says.
Wolverines are, in fact, real creatures that like cold weather. They build their dens in deep piles of snow.
But these days, the misunderstood and rarely considered wolverine is running out of places to go. Many parts of their current range— from Alaska to Wyoming — are becoming warmer and less snowy because of climate change. And even as suitable habitats disappear, human development is cutting into what little remains.
A plan is underway to reintroduce the creature into the Southern Rocky Mountains in Colorado, where wolverines once thrived and have since disappeared. They fell victim to unregulated trapping and to consuming poisoned carcasses set out for the wolves, bears, lions, and coyotes that American settlers targeted en masse in the 19th and 20th centuries. The wolverine’s managed return is part of the larger story of many threatened or endangered predators coming back to their original ecosystems, such as the grizzly bear’s possible restoration to Washington’s North Cascades, snow leopards to Central Asia, and the lion’s return to the East African country of Mozambique.
Like any wildlife restoration, these endeavors come with inevitable trade-offs. The return of the tenacious wolverine to its native range in the Southern Rockies may seem like a win for this elusive creature. But it’s also a gamble.
Some wolverine biologists question the ethics of capturing wolverines from the cold of northern Canada and bringing them to a more southern region that may not be able to support them as climate change warms our winters.
The debate leaves biologists and wolverine advocates weighing humanity’s responsibility to reestablish vanished species in environments where they haven’t existed in decades — or, in some cases, more than 100 years. It also has biologists scrambling with how best to hit the moving target of habitability when global warming ensures that the climates of today are mere tenuous snapshots in time.
Is moving a species, especially a cold-adapted one, into new habitats a life raft? Or another nail in its coffin?
Where’s a wolverine to go?
For what is effectively a giant weasel that often dines on dead stuff, wolverines have remarkably specific habitat needs.
Jeff Copeland, a board member of the Wolverine Foundation and longtime wolverine researcher, says the animals prefer to build dens in several feet of snow to provide their young — known as kits — with a temperature-controlled home away from predators and storms. Their sweet spot is an elevation somewhere around the treeline, not too high in the mountains away from where deer and elk die, but not too far down into the areas where humans, coyotes, wolves, and other predators live. This is why the species only occupies the upper elevations of the western US.
But it’s possible that researchers have overestimated the need for snow depth. Jason Fisher, an adjunct professorin wildlife ecology at the University of Victoria in British Columbia, agrees wolverines need snow to take advantage of their big, snowshoe-like feet, which are adapted to the drifts. However, he argues that wolverine preferences for colder habitats may have had more to do with human interference. He says wolverines in the lower 48 states may only den in deep snow because humans have relegated the species to remote places that also happen to have deep snow.
Regardless, both Copeland and Fisher say wolverines thrive in wide swaths of relatively unoccupied, cold territory — environments increasingly threatened by oil and gas extraction, logging, residential development, the recreation of terrain-seeking backcountry skiers, and climate change.
The US Fish and Wildlife Service agreed, deciding after years of indecision to place wolverines in the contiguous US on the threatened species list because of “climate change and associated habitat degradation and fragmentation.” And even though wolverines are expanding their range, they still live in small pockets of available habitat. Biologists worry populations may not be robust or close enough to intermingle and provide important genetic exchange, without which species with small populations run the risk of inbreeding.
“Even in places where they’re doing well, in the best of circumstances, they’re just really, really rare,” says Jake Ivan, a wildlife research scientist with Colorado Parks and Wildlife, the agency charged with restoring the wolverine. “It’s harder to make those populations stick and grow compared to some other species.”
Colorado’s audacious restoration plan
Decades ago, Colorado Parks and Wildlifedeveloped a plan to satisfy their mission statement to conserve and restore native flora and fauna. Since then, the state has actively reestablished wildlife in places where they flourished before colonization. Its successful track record includes reintroducing black-footed ferrets, river otters, lynx, and, more recently, gray wolves, which were released into Colorado’s high country in December last year.
If Colorado’s wolverine restoration moves forward, the plan calls for rehoming ideally up to 45 wolverines — 30 females and 15 males — from Canada and Alaska. Colorado’s wildlife agency would collect its returning cohort from trappers who legally kill hundreds of wolverines between Canada and Alaska each year. The idea is to replicate what Colorado did with lynx: Make saving wolverines more lucrative than killing them by paying trappers far more than the market value for their hides.
Colorado also has plenty of habitat, Ivan argues, including areas like the more than 260,000-acre Rocky Mountain National Park and other high-country wilderness areas. A population in the Southern Rockies could be a wolverine insurance policy of sorts — if the Canadian Rockies have a bad snow year and Colorado’s mountains fare better, reintroduction would essentially hedge the bets for wolverine survival and create more conditions that would help them thrive long-term.
“Having more [wolverines] in more places is generally a better thing,” Ivan says. “We’re in this era of crazy climate change and potential catastrophes in terms of wildfire and drought and long-term movement of snow layers. You get a wildfire in the wrong place, that can really take a toll on wildlife over a big area. If there’s only wolverines in four places and you take out one of those four, you just took a bad situation and made it really, really bad.”
While Colorado’s proposed reintroduction is not final, it is moving forward. The bill was introduced in March, passed the state Senate and House, and was signed by the governor in late May. The reintroduction, however, depends on the US Fish and Wildlife Service. The federal agency would need to create an exception to specific Endangered Species Act provisions that allow wolverines to be reintroduced — but only under certain conditions. The allowances would create a carveout protecting, for example, the state’s influential ski industry if wolverines were harmed during normal operations. The state plan also calls for compensating ranchers if wolverines attack their livestock. From there, Ivan says, wolverines would likely be released over a handful of years, scattered throughout suitable habitat.
But even if Colorado’s high country remains suitable for a stretch of some really good years — let’s be generous and even say 40 years — is it the right habitat beyond that time frame?
Since 2020, Colorado has experienced four of the five driest years in the last 128 years. Researchers at Colorado State University say the state’s precipitation future is uncertain, but models “predict a 5–30 percent reduction in both stream flow volume and snow-water equivalent” by 2050.
And according to the Intergovernmental Panel on Climate Change, mountain winters will have one forecast: shorter, warmer, and less snowy.
What do we owe to a species we once exterminated?
The question facing rewilding advocates across the globe, from those who want to bring wolves back to Scotland to those championing the return of grizzlies to California, is this: Does wildlife benefit from being reintroduced into areas where they haven’t lived in more than a century in the face of an uncertain climatic future?
The answer is complicated. On the one hand, Colorado’s plan could provide a buffer population, a reservoir of about 100 wolverines, to create an even more diverse genetic pool as other populations become more fragmented. On the other hand, as the planet continues to warm even more dramatically, the Colorado transplants could become marooned on a metaphoric island, surrounded by forbidding heat, inhospitable prairie, and habitat-destroying development.
Populations generally only need modest genetic diversity every few years to persist, Ivan says. Take the story of a wolverine named M56, a male juvenile that traveled almost 600 miles from Wyoming’s northwest corner to Rocky Mountain National Park, likelyin search of a mate, in 2008. If a male wolverine wanders into Colorado from somewhere else, like M56 did, the DNA from a single stranger could be enough to boost the health of a new generation. Alternatively, the state may need to consider periodically infusing the population with wolverines from elsewhere.
As the climate changes, many alpine and subalpine species, especially in the contiguous US, will exist on islands under projected climate scenarios. Wolverines in portions of western Canada and Alaska currently have vast, relatively connected swaths of habitat. Those in Washington, Montana, Wyoming, and Idaho already exist on mountain ranges surrounded by lower, warmer prairie.
So Ivan frets for wolverines either way — whether they are reintroduced or not.
“What is climate change going to look like? How fast is that coming? How fast are things going to change? Is it going to be as bad as we think? Is it going to be worse than we think? Will wolverines respond like we think or will they tolerate more than we think?” Ivan says. “I worry about all of those things. But I do think it’s important, and we have a good shot at it. It’s worth trying.”
“What is climate change going to look like? ... How fast are things going to change? Is it going to be as bad as we think?”
But Copeland, from the Wolverine Foundation, believes a reintroduction into Colorado is fraught with problems. He says people should not remove wolverines from other fragile populations, and some of the state’s transports will likely die after reintroduction.
He also believes some roving wolverines will get to the Southern Rockies on their own, even though Colorado is many hundreds of miles away from current populations. And it’s possible that even though not many have made that trek, hot-and-bothered wolverines might increasingly seek out cooler climes. Climate change will force species of all kinds to move not just up on the globe, but up in elevation. Wolverines could satellite from Wyoming or even Utah to seek out Colorado’s higher mountains. They could thrive there. And, Copeland says, we should let them.
“These are not bighorn sheep or elk or beaver. When you go into the Yukon or wherever and you trap a handful of wolverines, you’ve completely disrupted the integrity of the population,” Copeland says. “It’s just not justifiable.”
Justifiable or not, in Colorado, the wolverine reintroduction has been far less controversial than other efforts to bring back apex predators like wolves or grizzly bears. Wolverines in North America rarely prey on livestock and aren’t a threat to humans. Wolverines are elusive, which is why so few people have ever encountered one. That’s part of the reason so many of the people Watter talks to aren’t sure they even exist (and why Hugh Jackman was urged to visit a zoo to see one).
But how much do we continue to tinker with a species we already failed once? Do we let them try and recolonize on their own, or do we intervene in their lives again? Bald eagles, another predator and scavenger, and bighorn sheep, a rugged mountain animal, have been reintroduced in native ranges and thrived. On the other hand, many coral reefs restored by human intervention are not surviving a warming world.
Watters sees wolverines as the test case for how humans deal with wildlife in an era of climate change: “Maybe in some respects it makes sense to just put as many animals down on the map as possible and hope for the best in the future.”
