On an overcast March morning at a trailhead in eastern Idaho's Centennial Mountains, wolverine research technician Kyle Crapster eyed two snowmobilers from across the parking lot as they pulled avalanche safety gear from a sticker-emblazoned truck. He suspected they were heading for the steep, open slopes that help make this area west of Yellowstone National Park, known as Island Park, an international snowmobiling destination.

Wolverines share the snowmobilers' affinity for isolated alpine terrain with deep snow, and Crapster was part of a research team tracking the movements of both to learn if the traffic impacts the animals. He approached the two men to ask them to take a GPS along on their ride. One of them noticed his clipboard and the fluorescent orange bracelet containing the tracker, and cut him off before he could start: "I'm not carrying one."

Fortunately, such rejections are rare. About 90 percent of snowmobilers and skiers approached have taken the GPS units into the mountains. Since 2010, researchers have collected roughly 10,000 such GPS tracks in four Idaho national forests and one in Wyoming. They've fitted 23 wolverines with radio-collars in those areas, including two in the Centennials. Eventually, they'll compare the two datasets to see if the presence of people affects how the "mountain devils" behave, reproduce, and where they choose to live – things that could ultimately affect their survival.

Wolverines are scrappy scavengers, generally weighing between 20 and 60 pounds, with stout legs, snowshoe-like paws and sharp claws that equip them for travel near treeline. When a three to four-foot dump overwhelmed the researchers' snowmobiles in 2011, a GPS-collared wolverine cruised the stormy slopes and ridgelines as briskly as a human striding down a flat, dry trail. "They are just like a little super animal," says Kim Heinemeyer, a biologist with Round River Conservation Studies, a research nonprofit co-leading the study with the Forest Service's Rocky Mountain Research Station.

But they are also vulnerable. So far, their remote lifestyle has protected them from most of the pressures that other charismatic carnivores face – like development, livestock and logging. That, and their natural rarity, has also kept them relatively understudied. While there are thousands of wolverines in Alaska and Canada, plus more in northern Europe and Asia, the Lower 48 probably hosts fewer than 300. But no one knows for sure. It's clear that climate change threatens their snowy habitats, so they'll be considered for endangered listing this August, even as their populations in Idaho, Montana, Wyoming and the North Cascades are bouncing back from early 20th century trapping and poisoning. Yet the effects of increasing numbers of snowmobiles, helicopters, snowcats and skis in wolverine territory are uncertain.

Surprisingly, the Idaho State Snowmobile Association endorses the study. The potential for a listing has raised the stakes for everyone: Snowmobilers hope the study's findings will prevent large closures, while managers and scientists are optimistic that getting the recreation community involved early on could help wolverines remain relatively uncontroversial, even if listed.

"My hope is that regardless of the results, recreationists take ownership of this animal and become largely self-policing, and we don't have to force regulations upon them," says Jeff Copeland, a Forest Service researcher who started the project before retiring to direct the Idaho-based Wolverine Foundation.

Like Island Park, western Idaho's Payette National Forest is a snowmobile magnet. In 2008, a Forest Service plan to ease the pressure of increasing motorized recreation on wildlife and trails threatened to close thousands of acres there. But the proposed closures were based on educated guesses – not hard evidence – about how traffic might discourage wolverine movements or disrupt denning.

In response, the snowmobile association did something desperate people rarely do: They searched the scientific literature. That yielded a few anecdotes – one female abandoned her den when helicopters were nearby – but no proof that snowmobiles harm wolverines. Copeland's name was on many studies, so they called him. "He admitted that there was no science," says Sandra Mitchell, the association's public-lands advocate. "If there is an impact, we need to act responsibly. But to close the public lands because there's a perceived impact, that's not good enough."

Mitchell invited Copeland to speak at the International Snowmobile Congress in Boise in 2008. Together with several Forest Service biologists, they agreed that a wolverine and recreation study was overdue, and the snowmobile association offered to help the Forest Service promote and fund it.

It was an unusual alliance: Idaho snowmobilers have fought federal agencies in court for years over motorized recreation bans in national forest wilderness study areas, and over 70,000 acres of closures to protect endangered caribou. Copeland, for his part, says he hates riding snowmobiles, a necessary, but noisy, tool of his trade. In 40 years as a wildlife biologist, he's clocked countless miles on them and owns two old beaters to access his off-grid house. "I sure as hell would never ride one for recreation," he says.

Still, he wanted to maintain wildlife management's credibility by avoiding arbitrary closures. Most of all, he recognized a rare opportunity to improve the adversarial relationship between snowmobilers and the Forest Service. The snowmobile association, in turn, saw that Copeland didn't have an anti-motorized agenda. "Their position is that if you do good science and you come up with a result that says we are damaging wolverine populations by recreating on top of them, we will change our behavior," says Copeland. "That is a huge step. They came to the 'enemy' and said, 'We're going to trust you to do this.' "

That trust has been crucial to the study. When the project began, researchers weren't sure how snowmobilers at trailheads would respond. But the Idaho State Snowmobile Association encouraged its members to participate, and some snowmobile rental companies helped distribute GPS units. Local businesses provided beer and pizza discounts to riders that returned GPS units (as opposed to dropping them in pit toilets, which once happened). Yurt and helicopter skiing operators and ski areas have also begun equipping customers with GPS trackers.

It hasn't hurt that snowmobilers are confident that their sport does not harm wolverines. "It's not a sissy animal," says Mitchell. While other animals hibernate, wolverines sniff out mountain goats frozen in avalanches, devouring even the bones. They can take down prey 10 to 20 times their weight, like caribou or moose. Noisy engines should be no problem for a species with that kind of grit, she reasons, but admits, "Maybe that's wishful thinking."

Initially, no one knew if wolverines could coexist with intense recreation. Now that they've been captured in high-use areas, some individuals for five years running, it's clear they tolerate traffic to some extent. One female even migrated 100 miles last year and denned in the heavily used Payette National Forest this spring.

Though Heinemeyer is encouraged, the study needs to include more animals to justify policy decisions, and the wolverine's rarity makes accumulating a large sample tough. A preliminary analysis revealed some snowmobile impact: Wolverines seemed to move more during high-traffic weekends than during the quieter workweek. But it's not yet known if that creates difficulties finding food, burns too many calories, or hinders survival and reproduction.

Winter recreation plans for the Payette National Forest are on hold until the work is complete. If researchers do conclude that wolverines have limited tolerance, managers could consider smaller closures, seasonal closures during denning, or even reopening long-closed areas that aren't good wolverine habitat. "My sincere hope is that if there are any impacts, that we have this group of folks that continue to work together and figure out ways to sustain both winter recreation and wolverines on the landscape," says Heinemeyer.

There is another problem that makes the study even more relevant. Most researchers agree that female wolverines, which dig snow tunnels to birth kits in late February and March, need deep snowpack lasting until late April and early May, likely to protect their denning kits. "Where you don't have those (cold, persistently snowy) conditions, you don't have wolverines," says Shawn Sartorius, a U.S. Fish and Wildlife Service biologist based in Helena, Montana, who is overseeing the endangered species listing decision.

Climate change is the main threat motivating the proposed listing, but the study could help managers if dwindling snowpack means that winter recreation adds stress to wolverines. "Winter recreation is one of the areas where we have more control," says Ana Egnew, a wildlife biologist on the Payette National Forest. "Climate change is a bigger issue than the Forest Service can take on alone."

Back in Island Park, Crapster prepares to approach the next truck that pulls in. The driver, a sunburned construction contractor with two teenage boys, is curious about wolverines: where they live, what they eat, how the research team captures them. Researchers stash partial elk carcasses in traps that look like small log cabins, Crapster explains. The man accepts a GPS unit. "If we're harming anything, I wouldn't go there," he says. "I'm glad that (wolverines) are here."