The population of wolverines in the contiguous United States has rebounded to an estimated 250 to 300 since the early 20th century, when predator control in the West nearly wiped them out, the U.S. Fish and Wildlife Service said in its report.
The U.S. Fish and Wildlife Service said in their report that the wolverine warrants protection under the Endangered Species Act.
"After review of all available scientific and commercial information, we find that the North American wolverine occurring in the contiguous United States is a distinct population segment and that addition of this population to the lists of endangered and threatened wildlife and plants is warranted," said the agency.The agency said the impact of climate change constitutes a threat to the contiguous U.S. population of the wolverine and will likely be irreversible within the foreseeable future. The population of the wolverine of North America is likely to become in danger of extinction in the foreseeable future due to destruction, modification and curtailment of its habitat and range. (Left: historical wolverine distribution in western US)
The wolverine is the largest member of the weasel family, weighing up to thirty pounds. With its dark, shaggy hair and short bushy tail, the wolverine looks something like a small bear. It lives in northern forests. Wolverines are cousins to everything from sea otters to skunks. They are known for their voracious appetites, cantankerous dispositions, skunk-like scent for defense and preference for extreme alpine environments.
Wolverines need deep snow for successful wolverine reproduction because female wolverines dig elaborate dens in the snow for their offspring. The den structures are thought to protect wolverine kits from predators as well as harsh alpine winters. However, warmer winter temperatures are reducing the snow pack in the West, making climate change the "primary threat to the wolverine population," the report said.
Environmental models project the wolverines' habitat will shrink by roughly a quarter by 2045 and nearly two-thirds by 2099, agency wildlife biologist Shawn Sartorius said. (at left:Historical wolverine distribution overlaid on map of probable snow cover during denning period.)
That means the animals will not be added to the federal Lists of Endangered and Threatened Wildlife and Plants. Instead, it will join the sage grouse, plains bison and hundreds of other species on a candidate species list awaiting federal protection.
While the polar bear in 2008 was the highest profile species to receive U.S. government protection because of the warming global climate, the wolverine is also affected.
Scientists say wolverine numbers in the high country of Idaho, Montana, Washington and Wyoming have dwindled to fewer than 300 and they are virtually gone from the rest of their historic range in the lower 48 states -- including Michigan where the University of Michigan mascot is the wolverine. (At right: recent distributions of wolverines)
Wolverines, which eat meat and range from 17 to 40 pounds, need deep snow in seclusion to reproduce and raise their young. Mother wolverines dig elaborate snow caves for dens.
A study by the University of Washington and U.S. Forest Service Rocky Mountain Research Station predicts that a warming West will cut suitable wolverine habitat by 23 percent in 2045 and by 63 percent in 2099.
"The threats to the wolverines are long-term due to the impacts of climate change on their denning habitat, especially important to assist the species in successfully reproducing," said Steve Guertin, the U.S. Fish & Wildlife director for the agency's mountain-prairie region. "If we work with state and other partners to help the wolverine now, we may be able to counter the long-term impacts of climate change on their habitat and keep them from becoming endangered."Extreme winter sports are making it even more difficult for wolverines, with snow-mobliers and skiers seeking the rugged and remote terrain preferred by the people-shy animals.
But Fish and Wildlife officials say the animals must get in line behind other species deemed by the service to have a higher priority as candidates for listing.
Conservation groups praised the government's decision to acknowledge the wolverine's dwindling population, but this does not does not result in a plan to protect them.
"It's a tough species to restore because we still know very little about them but it is frustrating and disappointing that we will have to wait for years until they're actually listed," said David Gaillard, Rocky Mountain representative with Defenders of Wildlife.
Wolverine whereabouts and numbers have been tracked only recently, with an estimated 100 in the Sawtooth Range of central Idaho and a high-density population of up to 50 animals in Glacier National Park (left).
Development, including cities, roads and ski resorts, has confined wolverine range to isolated islands. Scientists say that places the animals at undue risk by forcing them to wander hundreds of miles in search of mates. The distance between the semi-isolated populations is growing, making it more difficult for the wolverine groups to exchange genes and maintain a viable population.
Environmentalists last petitioned in 2000 to have wolverines added to the endangered species list. Eight years later, the government said protections were not warranted.
Conservation groups sued, forcing the Fish and Wildlife Service to revisit -- and now reverse -- the decision by the administration of former President George W. Bush.
Wolverines join more than 250 animal and plant species considered candidates for federal protections.
The wolverine has a broader range in Canada and Alaska, territory separate from the newly designated distinct population segment in Montana, Idaho, Washington, Wyoming, Colorado, Oregon, Utah and California.
In Canada, wolverines are considered endangered in the eastern part of the country and a species of special concern in the western part of the nation.
Reuters, "Wolverine latest wildlife endangered by climate change", accessed December 15, 2010
Denver Post, "Feds: Wolverine warrants protection", by Harold Pankratz, accessed December 15, 2010
Google News, "Feds: Wolverines need protection but have to wait", accessed December 15, 2010