USFWS Logo U.S. Fish and Wildlife Service Banner
The Mountain-Prairie Region


U.S. Fish and Wildlife Service
134 Union Boulevard
Lakewood, Colorado 80228


October 21, 2003

Contacts: Lori Nordstrom (406)449-5225, x208
Sharon Rose (303)236-7917, x415




The U.S. Fish and Wildlife Service has evaluated a petition to list the wolverine under the Endangered Species Act and has determined that the petition does not provide substantial information indicating that listing may be warranted.

The Biodiversity Legal Foundation and five other organizations petitioned the Service to list the wolverine within the contiguous United States and designate critical habitat for it.  The Service determined that the petition and other currently available data is insufficient to determine wolverine distribution, habitat requirements, and whether there are threats to the continued existence of the wolverine.

Wolverines naturally occur in low densities.  Wolverines are difficult to study and rarely observed, so lack of sightings does not necessarily mean that wolverine numbers are declining.

“Very little is currently known about the wolverine,” said Ralph Morgenweck, the Service’s Director of the Mountain-Prairie region. “We will continue to seek new information on the biology, ecology, distribution, and habitat of the wolverine, as well s potential threats to its continued existence.  We anticipate that ongoing research will greatly improve our understanding of the wolverine and how its conservation can be incorporated in land management activities.”

Because much of the wolverine’s known range occurs in land managed by the U.S. Forest Service, that agency is leading a cooperative research effort with other Federal agencies, States and Tribes.  These groups will develop a scientifically based strategy for conservation of the wolverine.

A similar petition to list the wolverine was filed by the Biodiversity Legal Foundation in 1994.  The 90-day finding the Service published at that time determined that the petition did not contain substantial information to warrant listing.  Since then, little new information has been published regarding wolverine ecology.

The wolverine is the largest land species of the “mustelid” or weasel family, with adults weighing 17 to 40 pounds.  In appearance it is more similar to a small bear than a weasel.  It feeds primarily by scavenging on carrion.

In North American, wolverines occur in a variety of habitats, primarily boreal forests, tundra and western mountains throughout Alaska and Canada with the southern portion of the range extending into the contiguous United States.  The current range of the wolverine in the contiguous United States is believed to include Montana, Wyoming, Idaho, Washington, Oregon, and possibly California.  Within these states, the range and habitat requirements of the species is not well understood, thus the Service cannot use existing data to accurately delineate the historic or current range.  The historic range in the Great Lakes region and northeastern United States is difficult to determine because records are sketchy.  Until the Service has a better understanding of the habitat requirements of the wolverine, it cannot ascertain whether habitats in many states were historically capable of supporting the wolverine.

This finding is published in today’s Federal Register.  Additional information regarding the finding can be obtained at the Service’s web site at

The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 542 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 64 fishery resource offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.


         - FWS -


         For more information about the U.S. Fish and Wildlife Service,  visit our home page at


Email Us:

FWS Mountain-Prairie Region Press Releases

FWS Mountain-Prairie Region Home Page FWS National Website
PrivacyDepartment of the InteriorFirstGov
Freedom of Information Act (FOIA)
Who We AreQuestions/Contact Us