Ready for wolverines?
Colorado is planning on reintroducing wolverines in the near future. As state officials work to finalize the rollout of these predators, we want to know what questions you have. Email reporter Tracy Ross at tracy@coloradosun.com with subject line Wolverines. We may ask your question at an upcoming virtual conversation.
Wolverines will take a bite out of the Colorado Parks and Wildlife Commission meeting in Denver on Thursday when agency biologists unveil their plan for restoring the long-haired predators with bone-crushing jaws to the state.
They’ll be the first predator released in Colorado since 25 wolves were uncrated in Grand, Summit, Pitkin and Eagle counties between December 2023 and January 2025. Canada Lynx were reintroduced into the same habitat wolverines will be released starting in 1999, with CPW releasing 218 of them into the San Juan Mountains. They’ve since established a self-sustaining population with documented reproduction.
No date is set for releasing wolverines, as CPW has several steps to move through before they can put the animal’s considerable claws on the ground.
But finalizing the 106-page plan is a big step toward bringing more “charismatic critters” to Colorado, says Luke Perkins, agency spokesperson. And release of the plan is timely, as it comes a day after wildlife advocates filed a complaint against the U.S. Fish and Wildlife Service for failing to designate critical habitat for wolverines in Montana following their 2023 listing as a threatened species under the Endangered Species Act.
Somewhere between 300 and 400 wolverines live in the Lower 48 states, and the largest member of the weasel family is native to Colorado. But the last wolverine here was killed in 1919. CPW conducted a dozen surveys in the late 1980s to the mid-1990s searching for wolverines across the Western Slope and found none.
A single GPS-collared male was radio-tracked traveling from northwestern Wyoming into Colorado in 2009, however, and someone snapped his picture within 24 days of his arrival. None have been seen since.
But with Colorado having “probably 20% of wolverine habitat in the Lower 48,” according to Robert Inman, CPW’s wolverine program manager, “if we can reintroduce them here and get a population going, it will be a significant increase to the overall population” within the contiguous United States.
Varmint legislation
Colorado lawmakers in 2024 overwhelmingly approved the return of wolverines to the state’s alpine landscape. Legislation for the reintroduction passed with bipartisan support after cosponsors Sen. Dylan Roberts, a Democrat from Avon, and Sen. Perry Will, a Republican from New Castle, billed it as being “completely opposite of wolf reintroduction.”
Senate Bill 171 allows the U.S. Fish and Wildlife Service to designate an experimental population of wolverines in Colorado, which gives CPW the ability to manage reintroduction, like they’ve been able to with wolf reintroduction. That federal approval of a state-managed population of federally protected animals is allowed under section 10(j) in the Endangered Species Act. Designation will come only after the federal government reviews the reintroduction plan under the National Environmental Policy Act.
CPW is under intense scrutiny by Fish and Wildlife over what the service says are violations of the 10(j) rule during wolf-reintroduction activities, however. In a letter dated Dec. 18 service director Brian Nesvik told the agency it had 30 days to do a full accounting of all gray wolf conservation and management activities occurring since Dec. 12, 2023. If CPW does not comply, after 60 days, Fish and Wildlife could revoke the state’s authority and take over Colorado’s wolf project. CPW said it’s unclear if or how that situation would impact wolverine reintroduction, because it could still be years off. The agency is complying with Fish and Wildlife’s demands.
Senate Bill 171 also called for establishing a funding tool so ranchers who lose livestock to wolverines can be compensated. There is no deadline for when Colorado Parks and Wildlife should return wolverines to the state. But Perkins said the following requirements must be met:
- Establish the livestock compensation rule.
- Draft a communications plan that describes how the division will communicate to stakeholders and county commissioners in locations of proposed releases.
- Complete the process of establishing wolverines as a 10(j) nonessential experimental population in Colorado.
Why Colorado?
A model of wolverine habitat for the Western U.S. shows Colorado has approximately 11,500 square miles of ideal wolverine landscape: high enough, cold enough and devoid enough of people, with two-thirds classified as designated wilderness, national park, wilderness study area or U.S. Forest Service roadless area.
Colorado also has abundant ungulate and marmot populations — two favorite wolverine foods.
And although winter recreation may cause wolverines to avoid certain areas or abandon their dens, Perkins said “the 10(j) rule would help minimize regulatory burdens on current land uses as much as possible” and “it was a key component of the legislative process for several stakeholder groups whose industries are most likely to be affected by wolverine restoration.”
Drought is also bearing down on the West. But the plan says Colorado is still a good place to restore wolverines.
“Climate change is expected to have a generally negative impact on wolverine populations worldwide owing to their adaptation to cold, snowy environments. Colorado’s wolverine habitat will not escape the impacts of climate change, but its high elevation and topographically complex terrain is expected to buffer impacts as well, if not better, than lower elevation habitat elsewhere in the Western U.S.”
Wolverine rollout
The Colorado Wolverine Restoration Plan calls for the translocation of up to 15 wolverines per season for 3-plus seasons for a total of 45 translocated individuals.
When the time comes, wolverines will be released in coordination with the Southern Ute and Ute Mountain Ute tribes in one of three zones — mountainous regions north of Interstate 70, between I-70 and U.S. 50 or within the San Juan mountain range south of U.S. 50. CPW believes Colorado can hold about 100 wolverines once the population has been established. Suitable wolverine habitat occurs at about 10,000 feet elevation and above in Colorado.
“Wolverines naturally exist at very low densities wherever they are found” said Inman. “Fifty to 100 wolverines may not sound like a lot, but that is likely in the same ballpark as the historical capacity here in Colorado.”
Captures will occur between November and January, timed to annual trapping seasons for source sites that allow it, and to capture, transport and release pregnant females prior to them giving birth. Capture of males could continue through April.
Wolverines will be released into holding facilities at the Frisco Creek wildlife rehabilitation center in Del Norte, where personnel will be responsible for monitoring them for stress and health problems, coordinating collection and stockpiling game carcasses for feeding them and fulfilling all other animal care requirements, according to the plan. A CPW veterinarian will be on call while wolverines are in the holding facility if an emergency arises. Human contact at the pens (visual, auditory and olfactory) will be minimized to reduce habituation of the wolverines to human presence.
Releases will meet guidelines created by a Wolverine Translocation Techniques Working Group created in 2013, although Ivan said biologists “think more critically about wolverine biology in the reality that’s right in front of us now.”
“I feel we’ve done our due diligence,” he added. “I think we feel pretty good about what’s in the plan, realizing that no one’s ever done this and it is just a plan, and we’ll see what happens, and things are likely to change.”
Communication and compensation
“Wolverines are about 25 to 30 pounds, the size of a beagle dog or a corgi with long legs,” Inman said, “so depredation on cattle is just not really going to happen.”
They will likely kill sheep, however, “so it’s important to have a compensation rule in place that doesn’t put the burden of putting this animal back on the landscape on agricultural producers,” he added.
Ranchers in Grand County hit CPW with $580,000 in compensation claims for livestock lost to wolves in 2024; they were awarded $450,000. Ranchers submitted claims totalling $1 million in 2025; many are still pending. But the legislature allocated just $350,000 for compensation in 2024 and 2025, and it is unclear, amid a huge state budget imbalance, how much compensation money there will be going forward.
But Inman said wolverine kills “aren’t even going to be in the same ballpark as something like coyotes and wolves and so forth.” There are no records of them attacking or killing people, either. “It’s a 25- to 30-pound animal that has a big reputation, but they’re not as aggressive as their reputation suggests.”
According to a news release from CPW, the agency on Thursday will propose a wolverine depredation compensation rule that mimics the long-established rule governing mountain lion and black bear depredation of livestock. It will be the first of a two-step rulemaking process. Based on direction from commissioners informed by public comment, CPW will then make revisions to the proposed rule that have been requested by the commission and bring the updated rule back to the commission at a future meeting for final approval.
Tune in to the hybrid meeting in Denver to hear the discussion.