The wolverine, Gulo gulo, is the largest terrestrial member of the Mustelidae family, which also includes weasels and badgers. This powerful, solitary carnivore is elusive and wide-ranging, making it difficult to study in the wild. Its current distribution is a fragmented shadow of its former expanse across the northern latitudes.
The Circumpolar Range
Historically, the wolverine occupied a vast circumpolar belt that stretched across the Northern Hemisphere, covering boreal and subarctic regions of the Old World and the New World. In Eurasia, the species ranged from Scandinavia across Russia and Siberia, extending south to approximately 50 degrees North latitude. The North American population stretched from Alaska and northern Canada into mountainous and forested regions. Since the 19th century, this expansive distribution has been drastically reduced due to trapping, habitat loss, and fragmentation. Today, the global population is highly localized, confined to remote, high-latitude, and high-elevation wilderness areas.
North American Strongholds
The most stable and numerous wolverine populations are found in Canada and Alaska. Northern Canada, including the Yukon, Northwest Territories, British Columbia, and Alberta, provides vast tracts of continuous, undisturbed habitat. Estimates suggest that more than 10,000 wolverines reside in the Canadian territories and provinces.
In the United States, populations are concentrated in the remote, high-elevation areas of the western states. The current U.S. distribution centers on the Northern Rocky Mountains across Montana, Idaho, and Wyoming. Isolated, reproducing populations also exist in the Cascade Range of Washington and the Wallowa Mountains of northeastern Oregon. These lower 48 populations are small and highly fragmented, numbering fewer than 300 individuals. Transient males have been sighted as far south as the Sierra Nevada in California and the Southern Rocky Mountains in Colorado.
Essential Habitat Requirements
Wolverines inhabit a range of cold-climate biomes, including alpine tundra, taiga, and boreal forest. They are highly dependent on environments that maintain cold temperatures and significant snowpack. The presence of deep, persistent snow is particularly important for reproductive success.
Females must dig their natal dens into snow that lasts into late spring, typically from February through May. This deep snow provides insulation and security for the young kits from predators and harsh weather conditions. Den sites are often located in remote areas, such as snow-covered rock scree, boulder talus, or under uprooted trees near or above the timberline. This specific environmental condition, often requiring over a meter of snow depth, restricts their distribution to high-altitude or high-latitude regions. Wolverines prefer large, undisturbed wilderness areas and avoid high levels of human activity.
Population Status and Protected Areas
Because wolverines require large, undisturbed home ranges and occur at naturally low densities, their presence is often tied directly to designated protected areas. In the contiguous United States, many wolverines are found within national parks, wilderness areas, or national forests. These protected zones offer the necessary solitude and expanse, minimizing human development and disturbance.
The species’ low population size and reliance on specific habitat features have led to legal protections. In 2023, the U.S. Fish and Wildlife Service listed the wolverine population in the lower 48 states as threatened under the Endangered Species Act. This official status recognizes the vulnerability of the small, isolated groups in the Northern Rockies and Cascades. Monitoring efforts are conducted within these protected zones to understand the species’ distribution and ensure its persistence.