Wolverines in the lower 48 states are threatened by the low number of individuals contributing to their genetic diversity,  as well as the low overall population number; relative isolation from populations in Canada; global warming (which reduces the snow pack wolverines rely on for den sites); winter recreation in denning areas; and trapping in Montana.

Why Protection is Needed

Low populations – The lower 48 population of wolverines is reduced to a perilously low number.  Their breeding population is estimated at fewer than 50 individuals.  Compounding the problem, wolverines in the western U.S. are segmented into subpopulations effectively separated by low valleys, altered land uses or other obstacles. This has resulted in decreased genetic exchange and decreased ability for self-sustaining populations or repopulation of areas that may be suitable for recovery, such as the Southern Rockies and Sierra Nevada.

Global warming – Wolverines rely on snow packs that last into late spring to successfully raise young kits. Global warming is resulting in a loss of springtime snow pack and this loss may accelerate.  The result may be further isolation of different populations as the vital alpine habitat becomes restricted more and more to higher elevations.

Human disturbances and trapping – Resource extraction, roads, winter recreation (such as snowmobiling and helicopter skiing) and other disturbances near denning sites may negatively impact the ability of wolverines to reproduce.  In addition, Montana continues to maintain an annual trapping season for wolverines, despite their low population number and the risk it poses to maintaining a self-sustaining population.

Additional Information

Two years ago, the U.S. Fish and Wildlife Service (USFWS) declared that the last few wolverines in the continental United States should be protected under the Endangered Species Act, but that the Service had higher priorities at the time. Thus, these ferocious members of the weasel family earned the dubious designation of “warranted, but precluded” from federal protection.

The fate of the wolverine changed on February 1st, when the USFWS declared that the wolverine would finally be protected throughout its range in the lower 48 states.

Although wolverines are plentiful in Canada and Alaska, scientists believe there are fewer than 300 of these animals left alive in the entire contiguous U.S., with most of them inhabiting Wyoming, Montana, Idaho and Washington.

The scientific name for wolverine is Gulo gulo, meaning “glutton.” Wolverines are the largest member of the weasel family, and the home range of single wolverine may span several hundred square miles.

Wolf in Yellowstone in snowy environment with forested background
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