On the Edge
Wolverines, long admired for their ferocity and canniness, are so elusive that few people have even seen one. Now biologists are racing to find them before trappers do.
Springtime high in the Rockies, where the calendar reads May 9, but it's snowing in rattling bursts of graupel. After snow-shoeing for hours up a tilted, twisted drainage in Montana's Gallatin Mountains, south of Bozeman, I emerge into the headwaters cirque and stagger to where a cluster of researchers, led by Wildlife Conservation Society biologist Bob Inman, are gathered around three holes bored into the snow.
Nobody seems to think the climb has been exhausting except me. Wolverine researchers are freakish in their ability to cover punishing vertical terrain--and yet their subject routinely eludes them. "A wolverine will climb up an avalanche chute, climb up over a cornice, belly-slide down the other side, and keep running," says Tony McCue, then a field biologist on the crew. "They're so fast in covering their habitat, we just can't catch up with them unless they've decided to stop."
Inman, McCue, and the rest of the team fervently hope a wolverine has stopped somewhere under our feet. Even after the grueling ascent, the biologists seem energized by the knowledge that we're standing around the entrances to one of only a few wolverine natal dens ever discovered in the United States.
It's as close as I've ever been to wolverines, closer than all but a handful of people will ever come to one. Wolverines, the largest terrestrial member of the weasel family--a male weighs 30 to 35 pounds, an average female about 20--inhabit such austere territory in such meager numbers that even people who spend their entire lives exploring high-mountain backcountry may never see one.
Human encroachment of another sort could render the embattled mammal all but invisible: Trappers and outdoor recreationists, such as snowmobilers, might provide the one-two punch that limits current wolverine population growth. After spiraling to near extinction by the 1920s, wolverines in the Lower 48 managed a dramatic recovery in some states from the 1960s to the 1980s, aided by bans on wolverine trapping in most places. Today small, genetically isolated populations hang on in Montana and northwest Wyoming, central Idaho, and the Cascade Mountains in Washington. Still, the animal remains highly sought by trappers.
In 2003 conservation groups petitioned the U.S. Fish and Wildlife Service to review studies and consider the wolverine for protection under the Endangered Species Act. Under the influence of now-disgraced Interior Undersecretary Julie MacDonald, the agency found that there was not enough information about the animal to act on the request. (A federal judge ruled in 2006 that the agency's finding was "in error," and a formal review is now under way by court order.)
Although the agency's reasoning seems circular, it's true that until recently wolverines were North America's least-studied large carnivore. Before the 1990s, mythology for the most part substituted for science. In an early account, wolverines were such gluttons--their Latin appellation, Gulo gulo, means glutton--that they gorged themselves on prey, then forced their bodies into tight gaps between trees and squeezed the flatulence from their bowels so they could eat more. In Native American lore, the wolverine was a conduit to the spirit world and often served in the role of trickster-hero. Fur trappers called the wolverine the "devil bear."
Mention a wolverine to anybody who knows just a little bit about wildlife, and you will almost certainly hear about ferocity, and maybe a story about how these animals win battles against grizzly bears 10 times their size. This, too, is largely myth. Inman knows two of his collared wolverines have been killed by black bears, and another researcher described seeing a coyote snatching a wolverine by the tail and flipping it into the air repeatedly, as if toying with the animal.
Although there is evidence of wolverines killing moose trapped in deep snow, their bone-crunching jaws and powerful shoulders and neck--ideal for digging--are built to scavenge. A foraging wolverine can smell carrion, like a bighorn sheep or a mountain goat that starved or perished in an avalanche, buried under six feet of snow from a considerable distance. Because a female wolverine must forage for scarce carcasses, kits learn about high-country travel early in life. About nine weeks after giving birth in a natal den--an average of two or three kits is common--a female wolverine begins to move her kits to a series of temporary dens she digs closer to sources of food.
Inman and McCue suspect the den we've reached in the Gallatins is a natal one. McCue happened on it a few days earlier when, during a routine survey, he cut tracks made by the female and one kit and followed them to the entrances. For Inman, a lean man with a sturdy chin cupped in a reddish brown beard, this is a big moment. Partway through a scheduled decade-long study, Inman is trying to capture a kit to monitor for the project. This year none of the eight radio-collared females in his study group denned. The den we've hiked to is his only shot at digging out a kit until next winter. But a fresh blanket of snow combined with the absence of telemetry beeps makes knowing where--or even if--a female wolverine and her kit are huddled beneath our feet pure guesswork.
The plan is to excavate until a crew member can belly-crawl in and snatch a squalling six- to eight-pound kit, then surgically implant it with a radio tracking device about the size of a AA battery. It's an intrusive procedure, Inman admits, but other studies have demonstrated its relative safety for the young wolverine. So little is known about the wolverine in the United States that successfully implanting a kit today could advance the state of the science significantly.