The most famous wolverine is arguably a surly, lonely superhero human with deadly, retractable claws. One of the most famous actual wolverines, at least in the world of wolverine researchers, was named M56.
The wandering male with stubby legs embodied all the elusive mustelid’s personality traits when it trekked hundreds of miles from north-west Wyoming through desert and sagebrush sea to Rocky Mountain national park in central Colorado. There he spent a few years looking, presumably, for a mate, before turning back north, walking hundreds of more miles and getting shot by a ranch hand in North Dakota.
M56’s journey into Colorado, a state where wolverines hadn’t been spotted in more than a century, proved that male wolverines could cover significant ground. Recent documentation of a male wolverine in California – another state that hasn’t had a viable population since the 1920s – along with other isolated sightings, emphasizes the fact.
These are hopeful signs for a creature that, despite a century of challenges, remains a symbol of wildness in the American west.
Wolverines had largely disappeared from the contiguous US in the early 1900s as a result of poisoning and drops in big game populations. Thanks to environmental efforts in recent decades, today there are around 300 animals occupying pockets of Montana, Idaho, Washington and Wyoming. But the climate crisis looms over the snow-loving species, as do threats from backcountry recreation encroaching further into their habitat.
While wolverines may excel at the occasional walkabout, some researchers say the animal needs help re-establishing in remaining viable historical range like the mountains of Colorado and California. Other researchers say wait and let them wander.
The question of how much humans should intervene in the wolverine’s future will come to a head later this year when the US Fish and Wildlife Service faces a deadline to decide – finally – whether the species need federal protections.
“People talk about wolverines as being the embodiment of wilderness and that if there are wolverines, there are good wilderness areas still around,” said Eric Odell, species conservation program manager for Colorado Parks and Wildlife. “I think that there’s some truth to that.”
A curious carnivore
Wolverines never roamed the west’s mountains in high numbers. Glacier national park in northern Montana, for example, has some of the lower 48’s best wolverine habitat and is currently home to around 50, said Jeff Copeland, a longtime wolverine researcher and board member of The Wolverine Foundation. Conversely, the park has about 300 grizzly bears – another solitary species not known to exist in large densities.
They’re the terrestrial largest member of the mustelid family, growing up to 3ft long and weighing up to 50lbs, and walk on the soles of their feet like humans. Wolverines have a reputation for ferocity, but they’re actually curious and can be social.
The animal’s most impressive feature isn’t its claws, contrary to the comic book character, but its teeth and jaws able to tear and chew meat from frozen carcasses. Copeland once dragged a dead deer into the Sawtooth Mountains of Idaho in the depths of winter and waited for weeks while nothing touched the rock-hard meat.
“The ravens, the hawks, the coyotes, they couldn’t tear into it,” Copeland said. “Then a wolverine came along and ripped the thing apart and everything came in for this great meal.”
Unfortunately, the wolverine’s reliance on carcasses led to its near extermination in the contiguous US. Following European settlement of the west, ranchers began lacing dead animals with poisons like Strychnine and 1080 to kill predators like bears, lions, wolves and coyotes. The efforts proved effective not only on the target large carnivores, but also wolverines. At the same time, overgrazing by sheep and cattle and market hunting and mass slaughter of big game like elk, deer and bighorn sheep meant fewer carcasses for wolverines to find in the winter.
Where wolverines once roamed from Alaska and Canada to California and Colorado, their range largely shrank to just Canada and Alaska. But then states began reestablishing big game herds and in 1972, the US banned lacing carcasses with poisons like 1080. Eventually, wolverines reclaimed some of their historic range.
They wandered down into Montana, Washington, Idaho and Wyoming in great enough numbers that Montana trappers killed on average about 10 wolverines a year. Then researchers realized the threats to wolverines extended beyond poison and lack of food. Wolverines live large portions of the year in heavy snow and some research shows females likely require snow 9- to 12-feet deep to create dens. If their dens melt out earlier and they’re forced to move, their numbers could once again contract, Copeland said.
The great debate over reintroduction
Federal protections have long evaded the wolverine amid debate about how the climate crisis is impacting the species, and whether or not US populations are distinct from those living in Canada and Alaska.
The past decade has seen intensifying debate over whether or not wolverine should receive help to recover. In 2013, the US Fish and Wildlife Service proposed giving the species federal protections before withdrawing the proposal the following year, saying that wolverines in the lower 48 states aren’t distinct from healthier populations in Canada and Alaska, and climate crisis wasn’t as serious a threat previously believed because some female wolverines could den in less snow.
The listing proposal seesawed back and forth between the feds and courts, and in May 2022, a district court judge in Montana gave the US Fish and Wildlife service 18 months to decide, officially, if the species needs protections.
One of the best remaining unoccupied refuges for wolverines in the face of climate crisis may, ironically, be farther south, not north. Colorado’s mountains, with more than 50 peaks over 14,000ft and deep winter snows, could provide one more place for wolverines to eke out a living in a warming planet, said Jake Ivan, a wildlife research scientist with Colorado Parks and Wildlife. California’s mountains could also offer ideal habitat.
But such a proposal is thorny. The local skiing and timber industries fear that sharing space with a federally-protected species could hinder their operations, while others worry that making wolverines an endangered species would create more hurdles for using public land.
Odell understands the hesitancy, but says “from a biological perspective, the territory size for each wolverine is so large and the amount of habitat ski areas take up is miniscule, that the likelihood they set up a den in a ski area is really thin,” Odell said.
Another question is how the wolverines would get to Colorado. Human transport would likely be the quickest way, but Copeland believes they can make it on their own. Bringing them to Colorado could harm numbers in areas where they’re taken, he said. Wolverines would also likely die in the reintroduction process, which Copeland views as unacceptable.
States should focus instead on monitoring current populations and ensuring their stability instead of carting animals around, he argued. Strong core populations will result in wolverines searching for new places to live and while that may take time, their recolonization of states like Montana, Idaho and Wyoming, as well as the recent sighting in California, prove they can do it.
Ivan disagrees. Male wolverines may wander hundreds of miles on their own, but establishing a new population requires females also make the trek, the male and female find each other and that more wolverines also join the mix to introduce genetic diversity.
“That just doesn’t feel very likely to me,” he said. “We’re also up against a time crunch when it comes to climate change.”
Until the Fish and Wildlife Service makes a final decision, though, all efforts are on hold. If they’re not placed on the endangered species list, a state like Colorado could move forward. If they are placed on the list, wolverines could be reintroduced under a special clause that protects economic interests when reintroducing endangered species. But until then, everyone waits.
Even after decades of studying wolverines, Copeland will not say if the species should or shouldn’t receive protections.
“That’s a decision for the policy makers,” he said. “And I want them to make their decision based on biology not based on politics.”
