Wolverines
08/15/2024 12:38PM ● By Jennie Lay
Steamboat Springs, CO - On the heels of wolf reintroduction, another missing native Colorado species is about to make its return to the local alpine landscape. North American wolverines, the world’s largest terrestrial weasels, are set for restoration in their rugged Rocky Mountain home range.
Gulo gulo (wolverines’ Latin name means “gluttonous glutton”) were trapped and poisoned out of existence in Colorado in the early 20th century. The last confirmed sighting was in 1919. There are currently no known wolverines in Colorado, although one collared interloper in 2009 wandered down from Wyoming’s Teton Range, hung around Rocky Mountain National Park for a couple years, then meandered up to North Dakota before being shot by a cattle rancher.
Now, climate change has made Colorado one of the last best hopes for wolverines. Colorado’s high-elevation public lands harboring late-spring snowpack have a projected carrying capacity of 100-180 wolverines, poising the state to become a meaningful stronghold on a warming planet for this endangered species.
In May, a bipartisan group of state legislators led by Republican Sen. Perry Will and Democrat Sen. Dylan Roberts passed SB24-171, “Restoration of Wolverines,” and Gov. Jared Polis signed the bill atop Loveland Pass. Colorado Parks and Wildlife is now committed to establishing a viable population of wolverines in the state.
“We could be restoring a population in somewhat of a climate change refugium,” CPW’s David Klute said in a briefing. “Colorado’s high country is expected to weather climate change as good or possibly better than wolverine habitat that is provided by lower elevations and other parts of the range further north.”
Future climate models for Colorado show the state may be a lifeline for an elusive scavenger that relies on deep snowpack. Coupled with the political will to build complexity and sustainability in statewide ecosystems, Colorado’s large blocks of rugged and uninterrupted wilderness are sustaining some of the coldest and snowiest parts of the West.
Unlike the contentious reintroduction of wolves, wolverines are a simpler sale for the public. Mostly, they’re opportunistic hunters who will scavenge carrion or nibble on birds, eggs, fish, plants and small rodents. They live solitary lives above the treeline, claiming home territories of 200 square miles or more. Also, they dislike humans and our busy developments, which means they’re likely to steer clear of communities, ski areas and ranching operations. Probably the starkest contrast to last year’s wolf reintroduction is that the wolverine bill was written and approved by the state legislature in a bipartisan effort, not a ballot initiative.
Perpetuating its groundbreaking rewilding efforts, Colorado is attempting the first wolverine reintroduction in North America. There is no deadline, and there is a funding tool built into the legislation to compensate ranchers for any livestock lost to wolverines, although that threat is considered extremely low.
“Wolverines require huge, huge territories, so there won’t be that many of them. There aren’t that many of them even in areas where they’re not endangered... and they are cryptic. They will very, very rarely be seen,” says Joanna Lambert, a wildlife ecology and conservation biology professor at University of Colorado Boulder and a member of the Wolverine Coalition. “As someone who is thinking about... the measures that we need to take to address the biodiversity extinction crisis that we are living through – on the verge of losing a million species in the next couple of decades – what are the definitive, unequivocal actions that we can take part in to offset that? A big part of that is reintroducing species back to where they belong.”
Adult wolverines can range from blond to dark brown to black, with light lateral stripes, round ears, a stocky body shaped not unlike a small bear, and a long bushy tail. Weighing up to 40 pounds, they have big paws, strong jaws, and keen noses that can track the scent of a frozen buried carcass. They can run up to 30 miles per hour, swim, climb trees and communicate via vocalizations and scent-marking. They breed in the summer, give birth in the winter, and litters are typically two to four kits born in a den inside a debris pile at the snowy mouth of an avalanche chute. They live six to 10 years, and their predators include bears, wolves and mountain lions.
As for being a “gluttonous glutton” – consider their chosen habitat and home sites, then remember that wolverines are mammals with warm bodies. They don’t hibernate. They need to eat a lot to stay warm in those dens.
In November 2023, the U.S. Fish and Wildlife Service listed wolverines as threatened under the Endangered Species Act, but Colorado was already ahead of the game. State wildlife officials first started planning wolverine reintroduction in 1998, along with Canada lynx; but lynx restoration took precedence and then wolverines got caught up in federal protection status debates. Now CPW biologists are picking up where they left off in 2010. Their current preferred plan is to release up to 45 genetically diverse wolverines over three years (30 females and 15 males), spread over a spine of highest-altitude forest and wilderness along the length of the state.
Local to Steamboat Springs, U.S. Forest Service lands around the Flat Tops and Mount Zirkel Wilderness Areas have been targeted as primary wolverine habitat for potential drop zones.
Legislation is a victory, but only the first step. Yet to be hashed out is the final reintroduction plan, a donor to send us wolverines, and approval from the feds for Colorado to designate the returnees a nonessential experimental population (a.k.a. 10(j) designation). Prior to release, wolverines will have to be acclimatized at a wildlife rehab center near Del Norte, and they’ll be GPS collared for further study in the wild.
This is a novel reintroduction, so it will surely require adaptation along the way. “I do recognize the challenges and in no way want to diminish that. But, to me, the more the merrier,” says Professor Lambert, who has been on the frontlines of conservation for decades. “Let’s bring back what we can, when we can, and do something to address this global crisis that we are living in. Colorado has extraordinary potential because of our landscapes, because of our public lands, both state and federal. We’ve got the social carrying capacity for it in addition to the prey base and the landscapes.”
What’s next on the bipartisan rewilding agenda? In the wake of wolverines, it’s likely that Colorado’s drought-weary landscapes will meet opportunities for a resurgence of nature’s preeminent ecosystem engineers: beavers.
Gulo gulo (wolverines’ Latin name means “gluttonous glutton”) were trapped and poisoned out of existence in Colorado in the early 20th century. The last confirmed sighting was in 1919. There are currently no known wolverines in Colorado, although one collared interloper in 2009 wandered down from Wyoming’s Teton Range, hung around Rocky Mountain National Park for a couple years, then meandered up to North Dakota before being shot by a cattle rancher.
Now, climate change has made Colorado one of the last best hopes for wolverines. Colorado’s high-elevation public lands harboring late-spring snowpack have a projected carrying capacity of 100-180 wolverines, poising the state to become a meaningful stronghold on a warming planet for this endangered species.
In May, a bipartisan group of state legislators led by Republican Sen. Perry Will and Democrat Sen. Dylan Roberts passed SB24-171, “Restoration of Wolverines,” and Gov. Jared Polis signed the bill atop Loveland Pass. Colorado Parks and Wildlife is now committed to establishing a viable population of wolverines in the state.
“We could be restoring a population in somewhat of a climate change refugium,” CPW’s David Klute said in a briefing. “Colorado’s high country is expected to weather climate change as good or possibly better than wolverine habitat that is provided by lower elevations and other parts of the range further north.”
Future climate models for Colorado show the state may be a lifeline for an elusive scavenger that relies on deep snowpack. Coupled with the political will to build complexity and sustainability in statewide ecosystems, Colorado’s large blocks of rugged and uninterrupted wilderness are sustaining some of the coldest and snowiest parts of the West.
Unlike the contentious reintroduction of wolves, wolverines are a simpler sale for the public. Mostly, they’re opportunistic hunters who will scavenge carrion or nibble on birds, eggs, fish, plants and small rodents. They live solitary lives above the treeline, claiming home territories of 200 square miles or more. Also, they dislike humans and our busy developments, which means they’re likely to steer clear of communities, ski areas and ranching operations. Probably the starkest contrast to last year’s wolf reintroduction is that the wolverine bill was written and approved by the state legislature in a bipartisan effort, not a ballot initiative.
Perpetuating its groundbreaking rewilding efforts, Colorado is attempting the first wolverine reintroduction in North America. There is no deadline, and there is a funding tool built into the legislation to compensate ranchers for any livestock lost to wolverines, although that threat is considered extremely low.
“Wolverines require huge, huge territories, so there won’t be that many of them. There aren’t that many of them even in areas where they’re not endangered... and they are cryptic. They will very, very rarely be seen,” says Joanna Lambert, a wildlife ecology and conservation biology professor at University of Colorado Boulder and a member of the Wolverine Coalition. “As someone who is thinking about... the measures that we need to take to address the biodiversity extinction crisis that we are living through – on the verge of losing a million species in the next couple of decades – what are the definitive, unequivocal actions that we can take part in to offset that? A big part of that is reintroducing species back to where they belong.”
Adult wolverines can range from blond to dark brown to black, with light lateral stripes, round ears, a stocky body shaped not unlike a small bear, and a long bushy tail. Weighing up to 40 pounds, they have big paws, strong jaws, and keen noses that can track the scent of a frozen buried carcass. They can run up to 30 miles per hour, swim, climb trees and communicate via vocalizations and scent-marking. They breed in the summer, give birth in the winter, and litters are typically two to four kits born in a den inside a debris pile at the snowy mouth of an avalanche chute. They live six to 10 years, and their predators include bears, wolves and mountain lions.
As for being a “gluttonous glutton” – consider their chosen habitat and home sites, then remember that wolverines are mammals with warm bodies. They don’t hibernate. They need to eat a lot to stay warm in those dens.
In November 2023, the U.S. Fish and Wildlife Service listed wolverines as threatened under the Endangered Species Act, but Colorado was already ahead of the game. State wildlife officials first started planning wolverine reintroduction in 1998, along with Canada lynx; but lynx restoration took precedence and then wolverines got caught up in federal protection status debates. Now CPW biologists are picking up where they left off in 2010. Their current preferred plan is to release up to 45 genetically diverse wolverines over three years (30 females and 15 males), spread over a spine of highest-altitude forest and wilderness along the length of the state.
Local to Steamboat Springs, U.S. Forest Service lands around the Flat Tops and Mount Zirkel Wilderness Areas have been targeted as primary wolverine habitat for potential drop zones.
Legislation is a victory, but only the first step. Yet to be hashed out is the final reintroduction plan, a donor to send us wolverines, and approval from the feds for Colorado to designate the returnees a nonessential experimental population (a.k.a. 10(j) designation). Prior to release, wolverines will have to be acclimatized at a wildlife rehab center near Del Norte, and they’ll be GPS collared for further study in the wild.
This is a novel reintroduction, so it will surely require adaptation along the way. “I do recognize the challenges and in no way want to diminish that. But, to me, the more the merrier,” says Professor Lambert, who has been on the frontlines of conservation for decades. “Let’s bring back what we can, when we can, and do something to address this global crisis that we are living in. Colorado has extraordinary potential because of our landscapes, because of our public lands, both state and federal. We’ve got the social carrying capacity for it in addition to the prey base and the landscapes.”
What’s next on the bipartisan rewilding agenda? In the wake of wolverines, it’s likely that Colorado’s drought-weary landscapes will meet opportunities for a resurgence of nature’s preeminent ecosystem engineers: beavers.