Background and Recovery
Then and Now
Wolverines historically inhabited much of the northern United States, including the Sierra Nevada, Cascade and Rocky Mountain ranges, as well as parts of the Great Lakes and the northeast. Wolverines are solitary creatures, prefer high elevations at or above treeline, reproduce slowly and have large home ranges (as big as 350 square miles!)—all of which result in a naturally low population density. Sadly, these characteristics made the species susceptible to eradication in the late 1800s and early 1900s due to extensive unregulated 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 (USFWS) 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 USFWS to reconsider their initial finding. The court ruled in favor of Defenders in 2006 and ordered the USFWS to prepare a new finding by early 2008.
In March 2008, the USFWS once again determined that wolverines did not warrant protections under the Endangered Species Act. Later that year, Defenders filed another lawsuit against the USFWS 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 USFWS agreed to reconsider protections for wolverines.
In December 2010, the USFWS determined that protections for wolverines were indeed warranted, but put any further action on hold until protections for higher priority species were addressed. Then in 2011, USFWS agreed in a multi-species legal settlement that wolverines would be reconsidered for listing, and to make a listing determination no later than 2013 for wolverines in the contiguous U.S.
In February 2013, the USFWS officially proposed to protect wolverines in the contiguous U.S. as a ‘threatened’ species under the Endangered Species Act, citing the threats posed to their habitat by climate change. The agency will make a final determination by early 2014. Alongside the proposed listing, the USFWS also annoinced their proposal to designate the entire southern Rocky Mountains (southern Wyoming, Colorado and northern New Mexico) as an experimental population area for wolverines, which allows Colorado Parks and Wildlife to renew conversations with stakeholders about reintroducing the elusive animals to Colorado.