High Country Drifter

wolverine on snow

Will wolverines return to Colorado?

By Deanna Drew

You are unlikely to ever spot a North American wolverine, one of the most rare and elusive creatures in the forest. It lives in high elevations near tree line, hiding out in rocks and roaming the rough terrain and deep snow of the Rocky Mountains. This nomadic animal prefers to live away from activity, and travels alone over home ranges that can cover hundreds of miles of remote alpine habitat that is largely inaccessible to man.

Wolverines are considered one of the few remnants of true, pristine wilderness. They used to inhabit Colorado, but like their fellow predators the wolf and grizzly bear, were killed off by trappers in the early 1900s. The medium-sized animal is the largest member of the weasel family, with round ears and dark brown to black fur with blond markings. It has a bushy tail, large feet, and long claws, and can be mistaken for a small bear, badger, or porcupine. Due to the wolverines’ solitary nature and expansive territories, their exact locations and numbers are hard to pinpoint. Researchers say wolverine populations appear stable in Alaska and Canada, but estimate only a few hundred animals have moved back to the northern Rockies in Wyoming, Montana, and Idaho. Colorado’s last record of wolverines was in 1919, and not until 2009 did another confirmed wolverine wander into the state from Grand Teton National Park in Wyoming.

Regardless of the animals’ apparent absence, scientists say Colorado’s high country had, and still has, good wolverine habitat: vast amounts of mountainous, public land with extremely rugged terrain. They say the wolverine’s favorite type of land is no good for other forest practices such as recreation, logging, or prescribed burns, so their presence will not interfere with the state’s economy. And since wolverines are opportunistic eaters, they can survive on the seasonal variations of food available in their harsh environment better than other animals. For these reasons, wildlife officials are now considering a plan that would return the reclusive animals to the mountains and restore its species in the snowy Centennial state.

Colorado has successfully reintroduced other animals to the forest, including moose, river otter, and lynx; but the current effort to bring back the great gray wolf is full of controversy, mostly over potential impacts to ranching and hunting. However, the wolverine’s relative anonymity, independent nature, and lack of conflict with mankind could work to the animals’ advantage. Although wolverines are known as strong and fearless animals that can drive a bear from its kill, they weigh under forty pounds, mostly eat small mammals, and don’t attack livestock. Unlike wolves, wolverines scavenge deer and elk carcasses but will rarely take one down on their own, so they do not threaten the state’s large game.

Currently, trapping and hunting wolverine is illegal in all the lower 48 states. But even if wolverines are no longer vulnerable to the hand of man, according to a United States Fish and Wildlife Service report they remain susceptible to changes in the environment. Wolverines are mostly nocturnal and stay active all winter long without hibernating. Their young are born in dens dug deep under the snow by their mother; a thick mountain snowpack is necessary to keep the kits warm and safe from predators until the snow melts away in the spring, usually mid-May. Until fall, the young animals travel the steep slopes with their mother, learning how to navigate their challenging mountain landscape.

Because these animals are so dependent on snow to live and raise their young, biologists say the greatest threat to wolverine recovery in the wild is climate change. Based on the report, suitable wolverine habitat in the lower 48 states is projected to shrink in size and break apart, as warming temperatures diminish the spring snowpack. As a result, the number of wolverines that the habitats can support will decrease, as will the animal’s ability to travel from place to place.

Government officials have not yet decided whether they will reintroduce wolverines to Colorado’s high country and if so, where and how many. A previous proposal to establish a small experimental population in southern Colorado was later withdrawn. Wolverines naturally have small numbers, and exist in less density than any other carnivore in the mountains. Scientists estimate that the state’s high elevation public lands—the only suitable habitat for the far-roaming wolverine—could only sustain about 100 individual animals. Luckily, much of Colorado’s prime wolverine habitat is already federally managed as a National Forest, Wilderness Area, or National Park, with laws that protect the land from most human development.

Until a reintroduction decision is made, state and federal wildlife agencies are working together to conserve wolverines across the western United States. Someday, perhaps, these reclusive creatures will once again roam the high country in Colorado.