The secret life of wolverines

  • A yearling wolverine approaches a high-altitude trap

    Photo courtesy, Jeff Copeland

STANLEY, Idaho - Snow machines finally silent, four researchers walked toward a trap for elusive wolverines. All was still in the thick timber of the Sawtooth Wilderness until a growl made the hair on the back of my neck stand up.

Pacing inside the log-house trap was a wolverine about as big as a bear cub. "Ferocious-sounding beasts, aren't they?" whispered research team leader Jeff Copeland.

The crew quickly set up a camp table which would serve as the operating table. David Hunter, the state veterinarian, arrived to cut open the wolverine's stomach cavity and implant a radio transmitter. But first they had to anesthetize the animal. Copeland shined a light inside, ready with his jab stick. The animal let out an even nastier bloodthirsty growl.

Copeland jabbed for the animal's shoulder and connected. Five minutes later, he reached in and lifted the limp wolverine out of the trap and onto the table.

Another five minutes and Hunter had implanted the new transmitter - a 1-inch diameter tube about the size of a large shotgun shell - and had sewn up the animal's belly. Forty-five minutes later, the wolverine woke up, climbed out of the trap and scampered off in the snow on its big snowshoe-like feet.

The researchers named this mature male "Sox" for the patch of white fur on his left foot. Sox is one of a dozen wolverines researchers have trapped in central Idaho over the past three years - more wolverines than anyone knew lived in the region. A quick view of Copeland's radio-tracking map reveals over 800 sightings of 10 to 12 different wolverines in a 300-square-mile region.

This indicates that though they have lost ground throughout much of their traditional range, wolverines are probably not endangered in the Sawtooths. But just as the most extensive wolverine research study ever conducted in the contiguous United States has started to yield fruit, it has hit a giant snag. About $350,000 in research support from government agencies such as the Forest Service and from private foundations has dried up.

"It's a shame because there's still so much to learn," says Copeland, who is working on a master's thesis at the University of Idaho. "There's still a lot of basic, baseline stuff where we don't have any idea what's going on."

As Copeland searches for funds, biologists in Colorado, Wyoming, Washington, Oregon and California continue to look for wolverines in the Cascades, central Rockies and Sierras. So far, they haven't turned up many. Dave Kenvin, a wildlife biologist for the Colorado Division of Wildlife, has looked for wolverines all over the San Juan Mountains in southwest Colorado. They covered 800 miles of trail, and found none.

The only confirmed wolverine populations in the United States are in Montana, Idaho and Alaska. And there may be wolverines in Wyoming.

That's why Jasper Carlton, director of the Boulder-based Biodiversity Legal Foundation, filed a petition with the U.S. Fish and Wildlife Service to list wolverines as a threatened or endangered species in the lower 48 states.

The agency rejected the petition last April, concluding that there was insufficient scientific information to protect wolverines under the Endangered Species Act. Earthlaw, a public-interest law firm based in Denver, filed notice it intends to sue the agency.

A people-shy traveler

Copeland's research in central Idaho, along with Maurice Hornocker's studies in the Bob Marshall Wilderness in Montana, indicate that wolverines prefer the highest, most remote and most rugged mountain terrain.

"The only places you find them are in places where you don't find many of us," Copeland says. His aerial tracking shows wolverines travel immense distances over a short amount of time - sometimes as much as 50 miles a day.

"The hallmark of the wolverine is its almost insatiable need to be on the move," Copeland says. "They cross a topo map like we cross the street."

To make a living in the highest reaches of the mountains, particularly in the dead of winter, wolverines have to be extremely adaptable. Copeland says wolverines dig through 6 to 8 feet of snow to feed on rodents in hibernation. They cache winter-killed deer beneath the snow in strategic locations, and feed on them later.

"If they come onto a fawn or a calf elk, they'll kill it if the opportunity is there," Copeland says, "but they don't seem to follow the ungulates (deer and elk) on the winter range because they're not as good (as a mountain lion or bear) at taking them down."

How wolverines react to human pressures is another question the Idaho research team hopes to answer. Scientists speculate that logging, mining, road-building, heli-skiing, backcountry skiing and snowmobiling all affect wolverines. In the late spring, wolverines raise newborns, called "kits," in high-mountain dens among big boulders on talus slopes. During this time, it's possible that a skier or snowmobiler could cause wolverines to flee and abandon the kits, Copeland says. The Biodiversity Legal Foundation's Carlton also cites research in his petition that shows wolverines avoid clearcuts.

Montana still allows trapping of wolverines, which kills up to 18 animals per year. Hornocker's study in Montana discovered that wolverines caught in live traps often had missing toes and broken teeth, the likely result of getting caught and escaping a leg-hold trap.

Carlton wants trapping stopped in Montana, but, without federal protection, that's unlikely.

In the spring of 1994, Copeland and his research team caught two juvenile wolverines and implanted them with radio transmitters to better understand their behavior. How long do they stay with their mother? How do they learn to eat? When does a young male establish its home range?

Thus far, the results have been "pretty darn fascinating," Copeland says.

In the literature, he says, wolverines are described as solitary carnivores. "What we're seeing is a lot of social interaction."

Late in the summer, Copeland spotted Sox traveling for 30 miles with a young male, apparently "showing him the ropes' - finding food, eluding other predators, and staying out of trouble. He also saw a 3-year-old male wolverine playing in a meadow with a juvenile female.

Copeland suspects that Sox might be a polygamist, siring multiple litters in one season. "The old man is kind of the patriarch of the whole clan. He seems to know where everyone is, and he comes back to visit the adult females."

As of fall 1995, eight wolverines, including the two kits, were transmitting radio waves. Some of the animals will transmit for another two years, allowing Copeland to continue to track them.

"It never ceases to amaze me when I'm flying in the winter and I see a set of wolverine tracks crossing a 9,000- or 10,000-foot peak," he says. "I mean, what in the world is he doing up there?"

For more information, contact Jeff Copeland at 208/885-5868 or 208/883-1587.

Steve Stuebner reports from Boise, Idaho.

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