Colorado recently unveiled plans to move forward with the restoration of another species eliminated from the state in the 1900s, the wolverine. The effort is spearheaded by Colorado Parks and Wildlife, and supported by a wide-array of groups including scientists at the Denver Zoo, Colorado State University and a variety of conservation organizations.
The reintroduction effort has been in the works since 1997, and marks a significant step in Colorado's progress restoring species extirpated during the frenzy of trapping and poisoning during the 19th and 20th century. Wolverines would join a list of other native species returned to Colorado or recovered, including river otters, lynx, black-footed ferrets and wolves.
Colorado's law requires legislation be enacted to authorize reintroduction of threatened or endangered species, and because wolverines are listed as threatened under the Endangered Species Act, the Colorado legislature is now considering a bill to direct Colorado Parks and Wildlife to proceed. In Colorado, legislation can be adopted either in the Colorado legislature or by citizen ballot initiative. Among the co-sponsors is our local Rep. Barbara McLachlan. The prime sponsor is Republican state senator Perry Will from northwest Colorado, a former wildlife staffer.
Colorado wildlife officials first rolled out a proposal to reintroduce wolverines in the 1990s, in a study that looked at restoration of both lynx and wolverine. The lynx reintroduction proceeded first, in 1999, owing in part to easier logistics with a more abundant lynx population in Canada to draw upon. Once lynx were successfully established, conversations moved to wolverine restoration, and a stakeholder group met for several years from 2010 to 2013. However, progress stalled while court battles in the Northern Rockies played out about whether or not wolverines would receive consideration under the Endangered Species Act. That question was finally resolved last fall, with wolverines gaining protection as a threatened species.
The reason that matters is so wildlife managers know what legal parameters are needed to move forward with reintroduction, in this case under a rule defining wolverines in Colorado as a nonessential experimental population that provides management flexibility.
Wolverines have a deserved reputation, perhaps not quite as ferocious as the character of the same name depicted in Marvel Comics, but they are solitary with enormous capacity for long-distance travel across the most imposing high mountain landscapes.
Wolverines are the largest terrestrial member of the weasel family, and feast primarily on carrion. They opportunistically might eat a marmot or birds, but are extremely unlikely to bother domestic livestock like sheep.
Why return wolverines to Colorado? The Southern Rocky Mountains generally, and our high elevations ranges across Colorado, offer premium habitat most likely to persist in the face of a warming climate. A critical habitat factor for wolverines is persistent deep snowpack late into the spring, so that wolverines can den securely. An indicator of prime habitat is a one-meter snow depth on May 1, and Colorado's high elevations suggest longer-lasting snowpack in a warming climate than in areas farther north.
Returning wolverines to Colorado opens up a huge swath of additional habitat for the species, accounting for 20% of suitable habitat in the lower 48-states. Wolverines avoid people and development, and with the abundance of undeveloped high mountain habitat protected in wilderness areas like the Weminuche, Colorado is an ideal location for wolverine restoration.
An estimated population of less than 400 individuals in the lower forty-eight might pose one of the biggest challenges for reintroduction in terms of finding a suitably robust source population for wolverines. But the process could be well underway later in 2025, eventually offering lucky wildlife watchers a glimpse of an elusive symbol of wildness.
Mark Pearson is Executive Director at San Juan Citizens Alliance. Reach him at mark@sanjuancitizens.org.
