FWS weighs climate threat to fierce 'survivor' in Northern Rockies

Posted: Dec 20, 2012

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The wolverine can roam hundreds of miles, make short work of steep mountain faces and endure harsh winters on mountain ranges -- but it's no match for climate change.

So say biologists who see a dire threat in vanishing spring snowpacks that wolverines use as dens for their young.

The Fish and Wildlife Service is expected to decide next month on whether to protect the wolverine under the Endangered Species Act in what some see as the agency's most high-profile climate decision since the listing of the polar bear five years ago.

"Wolverines are organisms of the north, and if those places warm up, they are not going to like it. If spring snow shrinks, it defines where they den and where they live," said Kevin McKelvey, a scientist at the Forest Service Rocky Mountain Research Station and the author of a 2011 study on wolverines and climate change. "With wolverines, we have a very clean play on climate. Most organisms are not going to react like that."

A listing could also raise questions for how the government can protect an elusive animal -- difficult to track and research -- whose primary threat could be shrinking snow coverage.

"Wolverines are considered the embodiment of wilderness because they are such rugged characters, living in extreme alpine environments and over vast distances," said Kylie Paul of the nonprofit Defenders of Wildlife in Montana. "With climate change being their primary threat, it is difficult to consider what could be done, in light of the major problem of global climate change."

Dozens of environmental groups have been pushing for nearly two decades for protections for the wolverine in the lower 48 states. They may finally have their day as FWS is on track to issue a proposal by Jan. 18, 2013, spokeswoman Diane Katzenberger said.

The wolverine is currently listed as a "candidate" species, a designation FWS has used for plants and animals that merit ESA protections but are outweighed by other priorities.

The agency agreed to address the status of all its candidates under a massive 2011 legal settlement with the Center for Biological Diversity and Wild Earth Guardians. Under that agreement, the service is on deadline to decide on the wolverine by next December.

The agency agreed in recent months to accelerate its work on the wolverine, in response to another lawsuit from groups concerned about the trapping season for wolverines in Montana. Agency officials reported to a federal judge last week that they are on track for a January proposal.

The wolverine is best known as a mascot for the University of Michigan or a superhero from the X-Men than as a real, living creature in the Northern Rockies.

"Wolverines do not have a public constituency yet, and that's a problem because species conservation requires that the general public knows what the animal is, at least, and a lot of people don't," said Jason Wilmot, a biologist for the Northern Rockies Conservation Cooperative. "It's not a mythological creature, it's a real, live, flesh-and-blood creature, native to the United States."

'Tough as nails'

A member of the weasel family, the wolverine resembles a small bear with a bushy tail. They weigh 17 to 40 pounds and are 26 to 42 inches long. Their claws are significantly smaller than those brandished by actor Hugh Jackman's Wolverine in the X-Men movies.

The animal is a superhero in its own right. A wolverine has a home range of as much as 500 square miles. They roam rugged mountain passes with little effort. A wolverine tagged with a radio collar climbed the highest peak in snowy Glacier National Park in under 90 minutes, Wilmot said.

They can cover great distances: A wolverine from the Yellowstone area recently crossed into Colorado, and a wolverine from Idaho is now roaming the mountains of Northern California. They scavenge for food and can sniff out carcasses buried in the snow and eat the entire thing, including the bones. Their thick coats keep them so insulated, the snow around them doesn't even melt.

Even in Alaska and Canada, which have relatively large numbers of wolverines, population densities are small: four to five animals for 1,000 square kilometers (386 square miles). They mostly roam on their own and have few interactions with humans.

"You could spend your lifetime in the woods and never see one," Wilmot said. "They are tough as nails and will persist no matter what -- they are scrappy and mostly a survivor. They have an ecological niche in high altitudes and wintry conditions. Very few animals can survive there, cover the huge distances they cover or do such amazing feats."

There are believed to be no more than 300 wolverines in the lower 48 states, the Fish and Wildlife Service said. They live in the northern Cascades in Washington and the northern Rockies in Idaho, Montana and Wyoming. Their largest population is in Montana, especially around Glacier National Park. They are prized for their fur, and Montana has had a limited trapping season until this year, when a judge put a hold on trapping in response to environmentalists' lawsuits.

If the federal government protects the animals, the listing would not include Alaskan wolverines. The Fish and Wildlife Service determined that wolverines in the Rockies are a "distinct population segment" separate from Canada and Alaska, where populations are larger.

Historically, wolverines roamed in the Sierra Nevada and the southern Rocky Mountains. Many were killed in early trapping and predator-control efforts. There are scattered records of wolverines in the Great Lakes region in the 1800s, but there is evidence they were individuals dispersing from Canada and the area didn't have its own established population, Fish and Wildlife said.

Wolverines live in Arctic and Alpine regions; they are also found in Russia and Scandinavia. The International Union for Conservation of Nature's Red List of Threatened Species lists the wolverine as a species of "least concern" because of its wide distribution around the world.

Spring snow is key

The problem for wolverines is melting snow.

They rely on spring snow, which scientists say is particularly vulnerable to climate change.

When federal officials proposed the wolverine as a candidate for protection in 2010, they identified climate change as the biggest threat to the species. Fish and Wildlife had dismissed previous attempts to protect the species until new information about climate came into play.

"Across their worldwide distribution, wolverines are dependent on persistent spring snow cover for successful reproduction," the agency wrote in its listing proposal. "Essentially, wolverines use the coldest available landscapes within their geographic range."

Females build deep dens in the snow in the winter to give birth and use the dens to shelter and care for their young through a denning period that lasts until mid-May. Wolverines exclusively den in the snow, even when they are near other suitable habitat, like rocky caves. If rising temperatures bring spring two weeks sooner, it could significantly affect wolverines' ability to reproduce.

"From a scientific standpoint, the relationship between wolverines and climate is simple. Snow is a product of climate, a product of rainfall and temperature. It is not that wolverines react to climate because they use a particular plant type or are one or two steps away from the actual climate effects. ... Wolverines react directly to climate as far as we can tell through this snow relationship," the Forest Service's McKelvey said. "That makes them a more certain target for research into how climate change affects them. There is less uncertainty about wolverines than other species."

McKelvey and his colleagues looked at climate data and projections to estimate how wolverine habitat may change during the next century. They found that at least half of the existing wolverine habitat would persist for at least the next 50 years but that populations would likely become smaller and more fragmented. Thirty-seven percent of spring snow cover in wolverine habitat would persist through 2070-2099, according to their projections.


The Obama administration is expected to propose "threatened" or "endangered" protections for the wolverine next month.

Little has changed in wolverines' status since the Fish and Wildlife Service determined they were candidates for protection. Of 121 candidate species the agency has addressed in the past two years, it's proposed protection for 112 and withdrawn nine from the list.

Environmentalists who have pushed for wolverine protection hope the listing could draw more attention to the species' plight and the effects of climate change -- much as the polar bear listing did five years ago.

"The loss of mountain snowpack is something that people should be concerned about in general because it determines how much water there is in the summer. ... It matters a lot for water supply and stream temperature, which affects a lot of fish and aquatic species and people as well," said Noah Greenwald, the endangered species director for the Center for Biological Diversity. "It helps make people aware of the problem and what they are at risk of losing."

A listing, he said, could affect the wolverine trapping season in Montana, which has faced multiple lawsuits of its own in state and federal court. It could also open opportunities for reintroduction of wolverines in Colorado and Utah -- which would have suitable spring snowpack for the animals, even as some other parts of their habitat diminish.

Colorado officials have discussed a reintroduction program but put those conversations on hold while the wolverine's ESA status was in question.

Protections for the animal could give the state some certainty on management and allow the state to move forward with discussions on reintroduction, according to Eric O'Dell, conservation program manager at Colorado Parks and Wildlife.

"Once we know what that landscape looks like," he said, "we can assess and see if that creates a decision that is amendable to moving forward with reintroduction."

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