May 20 is the one-year anniversary of Colorado’s Restoration of Wolverines Act. North American wolverines — Gulo gulo luscus — were added to the U.S. Fish and Wildlife’s threatened species list in 2023, giving them federal protection under the Endangered Species Act of 1973. 

So, where are Colorado’s new wolverines?

Not here quite yet. Our state’s new law authorized Colorado Parks and Wildlife to create a plan for reintroduction. 

The result of bipartisan legislation, the law requires Colorado Parks and Wildlife to create rules and regulations for the reintroduction program. As of last week, Colorado Parks and Wildlife reports that they are in the final stages of drafting the plan.  

But perhaps the greater time investment is the requirement for Colorado Parks and Wildlife to work with the U.S. Fish and Wildlife Service over the next two years to develop a “10(j) rule” and complete the associated NEPA process, including public engagement and comment periods.  

What’s a 10(j) rule? Entitled “10(j) EXPERIMENTAL POPULATIONS,” it’s a provision in the Endangered Species Act providing a conservation tool for threatened or endangered species reintroduction. Given the strict regulations protecting these species, landowners and permit holders, such as ranchers or ski resorts, could have legitimate concerns about having a protected species released on or near their land. But with a 10(j) designation as “nonessential, experimental,” both the “take” prohibitions and consultation requirements of the Endangered Species Act are relaxed, easing the regulatory burden. See the service’s 10(j) fact sheet for more information.

So why such interest in wolverine reintroduction in Colorado? First, they belong here! Wolverines are native to Colorado’s High Country, but years of trapping and poisoning decimated their populations, while climate change and habitat fragmentation limited their natural range. Today, it’s estimated that only about 300 wolverines survive in the lower 48 states.

Second, wolverines are fascinating creatures. Solitary by nature, wolverines live at high-mountain elevations, often above treeline. Dense underfur provides excellent insulation, while 4-inch guard hairs shed snow and frost. Their large paws act as snowshoes.

Why “Gulo gulo?” Weighing between 15-40 pounds, wolverines are the largest terrestrial member of the Mustelidae family (from the Latin mustela, or weasel), a diverse family of carnivorous mammals that includes weasels, badgers, and pine martens. In Latin, “gulo” means “glutton” or “greedy eater,” reflecting the wolverine’s reputation as a powerful and opportunistic hunter and scavenger.

But despite this reputation — and teeth and claws to match — wolverines prefer to feast on carcasses of animals killed by other causes. Capable tree climbers, they’ll also consume small mammals, birds, eggs, fish and plants. Occasionally, they’ll even eat deer, elk and other ungulates, if weakened or trapped in deep snow. 

Wolverines use potent scent glands for defense and marking territory. There are no documented cases of wolverines attacking humans in the wild. And, despite the name, wolverines are unrelated to wolves.

Female wolverines, called “jills,” prefer deep snow for giving birth, digging their dens at the end of long tunnels to provide protection and insulation. 

Wolverines breed in the summer, but females delay embryo implantation, giving birth to 1-2 kits in late winter or early spring. Kits are born blind, weighing less than a pound, with white fur that lets them blend with the snow. 

For now, wolverine enthusiasts must be patient. According to Colorado Parks and Wildlife, “public scoping is expected to occur in 2025. A final rule is expected by early 2027.”

Meanwhile, learn more at one of the wolverine ecology and reintroduction series offered virtually and around Colorado this summer by CSU Extension, Defenders of Wildlife, and Center for Human Carnivore Coexistence. Stay tuned to your local extension office for event dates and locations.

“Get Wild” publishes on Fridays in the Summit Daily News. Frances Hartogh is a volunteer wilderness ranger for Eagle Summit Wilderness Alliance, an all-volunteer nonprofit that helps the U.S. Forest Service protect and preserve the wilderness areas in Eagle and Summit counties. For more information, visit EagleSummitWilderness.org.