Then and Now

Wolverines historically inhabited much of the northern United States from Maine to Washington, including parts of the Great Lakes region and the Sierra Nevada, Cascade and Rocky Mountain ranges. Wolverines are solitary creatures, prefer high elevations at or above treeline, reproduce slowly and have large home ranges (as big as 300 square miles!)—all of which result in a naturally low population density. Sadly, these characteristics made the species susceptible to rapid decline in the late 1800s and early 1900s due to extensive fur trapping and predator control.

Today, fewer than 300 wolverines are estimated to exist in isolated parts of Idaho, Wyoming, Montana and Washington, and scientists believe their “effective” population size—that portion that successfully breeds—may be as low as 35 individuals. On a positive note, there have been confirmed wolverine sightings in California, Oregon, Colorado and Michigan in recent years, indicating that they may still be expanding from their historic low in the early 1900s. Yet now the wolverine is at risk again from loss and fragmentation of its alpine habitat from human activities and future losses due to climate change.

Key Recovery Milestones

In 2000, Defenders of Wildlife and other conservation groups petitioned the U.S. Fish and Wildlife Service to protect wolverines under the Endangered Species Act. The Service initially determined that there was insufficient information that wolverines needed protection. However, Defenders followed up with a legal challenge in 2005, forcing the Service to reconsider their initial finding. The court ruled in favor of Defenders in 2006 and ordered the Service to prepare a new finding by early 2008.

In March 2008, the Service once again determined that wolverines did not warrant protections under the Endangered Species Act. Later that year, Defenders filed another lawsuit against the Service and the Department of the Interior for their failure to comply with the law and properly assess the status of wolverines in the lower 48 separate from much healthier populations in the Alaska and Canada. A settlement agreement was eventually reached in 2009, and the Service agreed to reconsider protections for wolverines.

In December 2010, the Service determined that protections for wolverines were indeed warranted [1], but further action has been put on hold until protections for higher priority species are addressed. As a result of a settlement agreement with two other conservation groups, a final listing decision and recovery plan is now expected by 2013 [2].