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.”