Tracking a Wolverine Through the American West

Researchers track a lost wolverine, Buddy, on his odyssey through forests, mountains and frozen lakes. 

By Jeff Wheelwright|Monday, February 3, 2014

A trail camera snaps a photo of Buddy on May 8, 2013. 

Pacific Industries

Sometime in 2008 a young male wolverine left his home in the mountains of Idaho. No one saw him go. He probably went west and then south, keeping to the highest ground and powering over obstacles, as wolverines tend to do. He forded a major river, the Snake, and a major highway, I-84, then had smooth sailing through the emptiness of eastern Oregon. Traversing a distance of 500 miles, he finally reached a forest near Truckee, Calif., in the central Sierra Nevada range. It had been decades since a wolverine roamed these woods.

As the largest terrestrial members of the Mustelidae (weasel) family, wolverines are creatures of snow, cold and peaks, but especially of snow. Their thickly furred, bowling-ball bodies are perfectly constructed to retain heat during blizzards. Their paws, seemingly too big for their stubby legs, let them bound over the snowpack without breaking through. Sniffing a dead deer buried beneath an avalanche, a wolverine bores down like a tunneling machine on full throttle. (Wolverines are scavengers, eating anything that once was alive.) Since females bear their young in snow chambers late in wintertime, the sites they select for denning have to maintain their snow cover long into spring to protect the kits. 

In short, no snow, no wolverines. On the basis of climate change’s threat to snow levels, the U.S. Fish and Wildlife Service found wolverines warranted listing as a threatened species in the continental U.S. in 2010. As of this January, the agency was in the process of determining if the federal listing should be finalized. According to the agency’s analysis, issued last year, the wolverine may lose a third of its current habitat by the middle of the century. The agency predicted that reduced snowpacks would hurt females’ denning; that home ranges would be pressed into tighter, more isolated spaces as animals moved higher with the retreating snow; that warmer temperatures would cause physiological stress.

Of course, long before climate change threatened the snowpacks, unbridled trapping and poisoning had driven most wolverines from the continental U.S. Wolverines hung on in the northern Rockies, but the thin populations in Colorado, Michigan, Minnesota and the Northeast were gone by the middle of the 20th century. Wolverines in the southernmost group, those in the Sierra Nevada, were hurt by a change in their food supply — deer, elk and bighorn sheep. Biologists think those animals were pushed out by livestock grazing in the high summer meadows of the Sierra. When winter came and the livestock were herded to lower range, little carrion remained for wolverines. Although a furtive few probably survived through the 1930s, the last confirmed Sierra wolverine was shot as a specimen in 1922.


Buddy was first spotted by a remote camera in California's Tahoe National Forest. 

U.S. Forest Service/Oregon State University/Katie Moriarty

But over the past 50 years, as trapping and high-elevation grazing were curtailed, wolverines stole down from Canada. Perhaps 300 live today in Montana, Idaho and Wyoming and the Cascade range in northern Washington. The young male that reached California was a big surprise, but the distance he traveled isn’t unheard of. Scientists have captured wolverines and let them go with radio transmitters attached. This kind of tracking has revealed beeline migrations of hundreds of miles with males moving farther and faster than females, often covering 20 miles in a day. 

Young male wolverines typically leave their birthplaces — often older males kick them out — while young females set up shop close to home. A 2-year-old male wolverine, testosterone spiking in his blood, does not know where the females are, but he takes his best shot and if he’s lucky, he lands in a territory where he can mate with two or three. Robert Inman, a researcher for the Wildlife 

How do biologists capture a spark? The Sierra wolverine, whose name is Buddy, made his first appearance in 2008. A graduate student named Katie Moriarty was working on a survey of martens, small, willowy, tree-climbing weasels in the Tahoe National Forest north of Truckee. The marten might be thought of as a Lilliputian wolverine, with habits and range that overlap. To detect martens for the United States Forest Service that winter, Moriarty used bait stations and motion-sensitive digital cameras. When a marten went up a tree after a piece of deer or chicken, its movement and body heat triggered a trail camera mounted about 10 feet away. Every few weeks Moriarty would retrieve the memory cards from about 30 cameras and download their contents onto her computer.

One day in March she was reviewing the latest images on her computer. Marten … red squirrel … another marten … coyote … the usual suspects. A technician in the lab had left her a sticky-note to be alert for an unknown creature from camera 371. She saw a large animal snuffling about the base of a tree. It had a shaggy ring of tawny fur running from its shoulders to its rump, so that its high, rounded back looked like a shaved head turning in the snow. Moriarty stared at the wolverine for a long time — it couldn’t be anything else — and then picked up the telephone.

The Forest Service fielded a SWAT team. Deploying additional cameras, dogs that sniffed feces (or scat), and people on skis and snowshoes, the research team combed a 50-square-mile area for signs of wolverine. On March 13, a second camera picked up the animal, and investigators followed its tracks away from the bait station. Everyone was excited, thinking that a long-lost remnant of the Sierra population had surfaced at last.

That notion was soon overturned. It’s become routine in wildlife biology to identify animals through the DNA in hair samples and scat. The Forest Service had installed hair snares at some of the bait stations. When the wolverine went up for the bait, a strand of barbed wire would snag hair from its coat. The analysis revealed the animal to be a male wolverine whose genetic ancestry was not Californian — an assessment made by comparison with wolverine pelts from California museums. Rather, the mysterious wolverine was a much closer genetic match to the wolverines in the northern Rockies, specifically to a subset in the Sawtooth Mountains of Idaho.

Next researchers analyzed carbon and nitrogen in the wolverine’s hair. Plants take up isotopes, or variants, of carbon and nitrogen in ratios that differ from one place to the next. When a wolverine in the Rockies eats a deer that has fed on the local plants, an isotopic signature is passed up the food chain into its hair. The same is true for the Sierra wolverines whose pelts were archived. When the researchers looked at the isotopic signature of the new wolverine, they realized it fell between the values for the two wolverine territories — just what you would expect from a predator that began its life foraging in the Rockies and then switched its diet to the Sierras.

Amanda Shufelberger is a wildlife biologist for Sierra Pacific Industries, which owns timberland in the Truckee area. Among her duties she surveys martens, foxes and other carnivores on company land. In fall 2008, the wolverine started showing up on her trail cameras, too. In the photos and video snippets he looked healthy, and definitely well-fed. A camera even captured him gorging himself on raw chicken and lolling on the snow like a pasha after a banquet — the wolverine’s scientific name, Gulo gulo, means “gluttonous glutton.”

Since the wolverine was stranded without a mate, the news media depicted him as lovelorn. Shufelberger and Chris Stermer, a biologist for the California Department of Fish and Wildlife, described him as “lost.” The cameras watched him roam a 300-square-mile block of forest as if he were searching for something. Shufelberger, touring the bait stations on her snowmobile, would look for his tracks and say to herself, “Has my little buddy been here?” When a newspaper reporter wanted to name the animal Randy because he was horny, Shufelberger replied, “No. His name is Buddy.”


Biologist Chris Stermer prepares a bait station on Sierra Pacific land. Copper wires, visible below the chicken leg, snag Buddy's hair for DNA detection. 

Jeff Wheelwright

Some experts doubted that Buddy could have come all the way from Idaho on his own. Noting the proximity of Interstate 80 to the initial sighting, Shufelberger and Stermer wondered if someone had trapped him up north and brought him here. But that possibility weakened when additional wolverines from the northern Rockies relocated to distant habitats containing no females. A young male with an implanted radio transmitter, known as M56, took off from northwestern Wyoming in April 2009 and arrived in northern Colorado in June, the first wolverine detected in Colorado in perhaps 90 years. In Oregon, where there had been fleeting reports but no confirmed wolverines, trail cameras observed three males in 2011.

The research biologist in charge of the Oregon work, Audrey Magoun, then with the U.S. Forest Service Rocky Mountain Research Station, thinks some wolverines, male and female alike, may avoid the normal territorial competition for mates. Rather, they settle in a productive, vacant area and wait for a breeding partner to show up. It could be what Buddy is doing, she contends. “This scenario has a much lower chance of [his] eventually breeding,” Magoun wrote in an email, “but it is one way to deal with overcrowding. As long as it works some of the time, then individuals with that ‘personality’ will remain in the gene pool.”

To Jeffrey Copeland, who specialized in wolverines for the U.S. Forest Service and now heads the Wolverine Foundation in Idaho, that argument fails to stand up or make much sense. “How’s he supposed to reproduce?” Copeland asks. “His range ought to be a function of females’ range. He should leave. It’s fascinating that he doesn’t.”

Whether stymied by highways or simply unwilling to move, Buddy has established a home on the piney crest of the Sierras. Shufelberger and Stermer, though they have other work, still keep tabs on him during the snowy part of the year. Camera stations rarely pick up wolverines in summer. Trying to beat the heat, the animals withdraw to remote pinnacles, and with more game available, they aren’t attracted to bait.


In March 2008, a second camera picked up Buddy, and investigators followed his tracks away from the bait station. 

California Department of Fish and Wildlife

Between them, the two biologists have compiled a thousand images of Buddy, counting stills and video, and they’ve confirmed his DNA 18 times. But each winter begins with uncertainty about his survival. “He’s never not there,” Shufelberger says, as she unloads her snowmobile from its trailer. She admits she has grown attached to a virtual creature. Wolverines are so elusive that they often exist only as pixels in a camera or beeps on a radio receiver, and it follows that when a wolverine disappears from detection, it may well be dead.

Only three human beings have seen Buddy in the flesh, and just one has photographic evidence. In May 2012, a solo backpacker saw a wolverine gallop across a frozen lake at dusk, and snapped a picture with his cell phone. Without the photo, the camper’s sighting would have been filed as unverified.

It is January at 6,400 feet on Little Truckee Summit and three snow machines roar into a forest of lodgepole and Jeffrey pine. Immaculate white meadows, threaded by iced-over streams, peek briefly through the trees. Like a rug thrown over a scratched floor, the snow masks the twiggy litter of the terrain, and the landscape rushes past in a tableau of green, brown and white. 

After four miles Stermer stops near a grove of lodgepoles. He clambers into the woods through 4 feet of snow. He straps a trail camera to a trunk, positioning it about five feet high. Then he affixes an array of copper brushes, the kind used to clean rifle bores, but used here for obtaining hair samples. Next he ties a raw chicken leg to a stout string and screws the string into the tree so that the chicken hangs above the brushes. “We want the wolverine to fight a bit to yank the bait off,” Stermer says, “so he will leave some hair.”

In discussions, Stermer takes pains to say “the wolverine” instead of “Buddy” because he thinks his position with the Fish and Wildlife agency calls for that formality. “I don’t want people to say, when I talk about him, ‘Don’t you have any real work to do?’ ” he says.


Buddy is caught on camera gnawing a hunk of meet from a bait station on Feb. 8, 2010. 

Sierra Pacific Industries

“Our job is to survey populations,” Stermer continues. “If it’s not breeding, we’re only gathering information on a recently arrived wolverine. If we found a second wolverine and a family, we’d probably [catch one and] attach a transmitter. I can’t justify the cost of running more than a camera or two. ... I have to have a scientific purpose. And I don’t.” 

Stermer buries a second chicken leg in the snow. “To make a natural presentation,” he says, converting supermarket chicken into carrion. The last step is to douse the suspended meat with a liquid called Gusto. It’s a concentration of skunk, offal and hair that trappers use to attract fur-bearing animals. The ferocious aroma of Gusto cuts through the wind and pervades the pines.

Shufelberger maintains a camera station a few miles farther on, in a thin stand of white fir. She’s making her first check today. Her hopes are high because this is Buddy’s “magic chicken tree,” the most reliable site for detections. The bait is gone, but the 69 pictures on the memory card show only martens, squirrels and blank shots triggered by waving branches. “Bummer,” Shufelberger says. Well, she has additional cameras to check. She puts a fresh cache of chicken into a tangle of wire and forges back through the drift to the snowmobiles.

Why not introduce a mate for the wolverine? To bring in a female or two and jump-start a population is the obvious solution to Buddy’s reproductive predicament, but, as Shufelberger points out, he would probably expire of old age before the necessary paperwork could be completed. The environmental ramifications of re-establishing a long-absent species in California would need hard scrutiny. 

The move by the U.S. Fish and Wildlife Service to list the animal as threatened under the Endangered Species Act includes scenarios for establishing wolverines in their former range, with Colorado taking the lead; the male stranded in Colorado, M56, had chosen an excellent spot in the southern Rockies and was already fitted with a transmitter. The agency considers the Sierra Nevada a candidate for translocations sometime in the future, as well.

Shawn Sartorius, the lead biologist for the federal project, explains, “We’d like to see them continue to expand — naturally or with help. We predict we’ll lose a lot of habitat [to climate change], and so while conditions are favorable, let’s get wolverines into a habitat that will be good for the foreseeable future. The projection is that the Sierra will maintain its snow.” Given Sartorius’ timeline, though, Buddy may miss the boat for a mate.

In late January of last year, Shufelberger sent an email with the title “BUDDY’S ALIVE.” The message read: “Whew…. I just got him on one of my survey cameras in a new place on the Henness Pass Rd.... Looks like he was last there Jan. 9.” A day later — the day after she and Stermer put out fresh bait — the wolverine appeared at his magic chicken tree. “He traveled 8.08 miles in almost exactly 24 hours,” Shufelberger wrote, marveling.

 Buddy returned to his favorite spot several times during 2013. From her digital photo album, Shufelberger passed along the year’s best shots. The picture taken Jan. 10 shows Buddy having mounted the tree. Fresh snow sifts from the boughs of the forest. He’s clamped the claws of all four feet onto the rough bark like a lineman gripping a telephone pole. In profile, his nose is inches from the chicken, and the gleam in his eye seems to say: For a wolverine, life doesn’t get any better than this. 

[This article originally appeared in print as "Where's Buddy?"]

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