Wednesday, February 4, 2009

Wandering wolverine surprises biologists

Two-year-old Gulo gulo caught in foothold trap on arid lands north of Idaho Falls

Express Staff Writer

A young male wolverine runs through a snowy meadow in Idaho’s Centennial Mountains moments after its recent release. Wildlife biologist Bryan Aber, who took this photograph, transported the two-year-old animal to the rugged area after it was caught but not injured in a foothold trap in a high desert area north of Idaho Falls. Photo by

The undulating high-desert steppe that stretches on for miles north of Idaho Falls isn't typical wolverine habitat. Rather, it's where you'd expect to see pronghorn antelope speeding off into the distance.

But that apparently didn't matter to a young male wolverine that recently found itself on the wrong side of a bobcat trap set by a trapper from the nearby town of Menan.

When the trapper arrived at the trap set among tall sagebrush he found the animal waiting unharmed. Contacted by the trapper, a wildlife biologist with the Caribou-Targhee National Forest was able to sedate and remove the wolverine.

Biologist Bryan Aber whisked the animal, whose Latin name Gulo gulo means "glutton," to the Driggs veterinary clinic. The clinic's vets have helped with wolverine research in the past.

The wolverine's capture comes at a time when the Idaho Department of Fish and Game, Forest Service and nonprofit Wildlife Conservation Society have come together to jointly fund a wildlife biologist position headed up by Aber. As part of the job, Aber manages wolves, grizzly bears and wolverines that occupy lands next to Yellowstone National Park in the upper Snake River region.

After a thorough checkup, the vets implanted an internal radio transmitter in the wolverine to allow its movements to be tracked. According to Fish and Game, internal transmitters have proven successful in the past.

Though the tapered bodies of wolverines make the use of traditional radio collars difficult, the Fish and Game also decided to fit the animal with a GPS tracking collar that will provide its exact time and location data for as long as it remains on, typically about 15 weeks.

After a brief holding period, the animal was released in the high-elevation Centennial Mountains to the north on the Idaho-Montana border, considered better habitat for wolverines. Aber and other biologists will track the wolverine, hoping to learn what attracted him down into the Menan area. They'll be specifically watching what landscapes the wolverine uses to cross from mountain range to mountain range, Aber said.

"We can start to figure out what areas might be more important for crossing points," he said.

This information may help conservationists identify lower corridors—which are often privately owned—that could be protected through conservation easements.

Because so little is known about these shy animals, it's even possible that the young wolverine knew where he was going, said Gregg Losinski, Fish and Game's Upper Snake Regional conservation educator. The animal may have been using nearby riparian lands to travel between mountain ranges.

"It could be perfectly within its range," Losinski said. "We just don't know."

With its release in the rugged Centennials, which are just a short distance away from other remote backcountry areas, predicting where the young wolverine will end up next is anybody's guess.

One thing biologists do know about wolverines is that they really like to travel.

Several years ago, Wildlife Conservation Society scientists equipped a wolverine captured in Wyoming's Teton Range with a GPS collar to better understand the habitat needs of this largest member of the weasel family, which can weigh up to 55 pounds.

The wolverine immediately traveled from the Tetons to the Portneuf Range in Idaho and then back again, covering 256 miles in only 19 days. It then trekked to Mount Washburn in central Yellowstone and back to the Tetons in a week, a distance of 140 miles. In all, the wolverine covered 543 miles in 42 days before its collar fell off.

According to Robert Inman of the Wildlife Conservation Society, the tracking data suggests that wolverine populations may function over a "huge geographic scale."

Many conservationists consider wolverines, which also inhabit the scenic mountain ranges surrounding the Wood River Valley, a threatened species, and have petitioned the U.S. Fish and Wildlife Service to list the animal under the Endangered Species Act. They claim that as few as 550 of the secretive animals survive in the lower 48 states.

The Fish and Wildlife Service has yet to announce whether it will grant the request.

Jason Kauffman:

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