While legend paints the wolverine as a solitary, blood-thirsty killer, there is another, more complex image of the wolverine that is just beginning to emerge. This episode of NATURE takes viewers into the secretive world of the largest and least known member of the weasel family, revealing it to be one of the most efficient and resourceful carnivores on Earth. Buy the DVD. This film premiered November 14, 2010.

Hardy, elusive, and smart, the wolverine dominates the harsh Alaskan wilderness.

Wolverines are among the most elusive creatures on the planet. They seek out the toughest terrain – the most rugged, remote and fiercely raw – and they’ve always been scarce to begin with. So they’re hard to find. They weigh only about 30 pounds, but they have a ton of attitude and a reputation to match. They eat everything, dead or alive, warm or frozen, and will climb anything, even mountains. It’s impossible for humans to keep up with them. They’re built to travel long distances with minimum effort across deep snow or up the sides of sheer cliffs. They roam an enormous territory of about 500 square miles – a home turf larger than an average grizzly bear’s. And they share it only with their immediate family. It’s “no trespassing” for everybody else.

Few researchers have observed wolverines in the wild, though some have tried, for years on end. Most must settle for capturing their images on remote cameras, tracking them from a distance, and getting to know them from their DNA. Those that study them become completely captivated by them, full of admiration and respect for these totally outrageous and independent creatures. Author and wolverine enthusiast, Doug Chadwick, puts it this way: “Like most of the guys on the project, what I really want to do is just be a wolverine. I want to go where I want to go, do what I want to do, bite who I want to bite, and climb what I want to climb.”

Yet there is one man whose experience with wolverines has been completely different. Wildlife filmmaker Steve Kroschel has spent 25 years with wolverines, and has even shared his home with them. Caring for injured and orphaned animals on a sixty-acre refuge in Alaska, he is one of the few men in the world to raise wolverines in captivity. The two orphans he has cared for since their birth have become his lifelong responsibility – and they are a handful! But he remains their committed and devoted advocate, a more than willing substitute parent to these remarkable animals he has come to love.

Photos by Gianna Savoie/©WNET.ORG, ©2009 Kory Pettman, and ©WNET.ORG Properties LLC

Doug Chadwick seeks out remarkable stories of the natural world and brings them to the public. With ten books and hundreds of articles to his name, he’s traveled the globe from Hawaii to the Himalayas. But it’s when he returns to Montana and hits the wolverine trail as a volunteer with the Glacier Wolverine Project that Doug feels he’s on sacred ground.

Doug Chadwick writes about the elusive wolverine as well as the experience of tracking wolverines through the harshest of conditions in The Wolverine Way.

Page 19:

Using an overhead pole attached to the front of the box trap, I levered the lid open wide. Like most captive wolverines, M1 waited a while, evaluating the sudden change before jumping out. And as usual for him, he didn’t run very far before he stopped cold and looked over his shoulder as if he’d suddenly remembered the beaver carcass left in the trap and was wondering why the hell he shouldn’t go back and take it along with him. He then started circling us at a distance of 40 to 50 feet, pausing to rub his belly and urinate on some alder brush nearly buried in snow, scent-marking the branches. After all, this was his territory. He had a claim to that beaver carcass we’d used for bait.

Marci Johnson, a former assistant on the project who continued to volunteer on breaks from her graduate studies in wildlife, had told me that when she raised the lid on a trap that held M1 one time, he didn’t leap out at all. He jumped atop the front of the box and perched there, regarding her, as if challenging Johnson to make the next move. Her take on M1 was, “He’s exactly what I think a wolverine is supposed to be: fearless.”

Once released from a trap, no wolverine we’d handled had ever attacked us or attempted to bluff us into leaving by making threatening rushes. Still, wolverines have been reported fighting over food with larger carnivores, up to and including grizzly bears. That wolverines were willing to even try driving off a full-grown grizz was astounding. The fact that they sometimes succeeded tended to stick in your mind when one was circling, especially when the circler was a big gnarly guy with anger management issues like M1.

Pages 20-25:

This unprecedented study of the most important population of wolverines left in the lower 48 states had been underway since mid-2002. I was a volunteer… it wasn’t long before all my outdoor clothing and gear began to smell like dead beavers and live wolverines.

To this day, I can’t quite explain what drove me to get involved in the first place. Curiosity, naturally; my life has largely been ruled by a fascination with wild creatures. The fact that I was a wildlife biologist who’d become a journalist and sorely missed doing hands-on research also played a role.

Then there was the lure of the setting itself. Glacier National Park is the centerpiece in the section of the Rockies many call the Crown of the Continent. When I’m away from this tall, never-tamed country, I ache to be back within its folds the way other folks miss home. I chose to live close by the 1,500-square-mile reserve, and it’s never taken much of an excuse to get me out hiking and skiing its contours on a moment’s notice. It makes sense to me to wander around in Glacier purely to air out the soul.

But there was an especially pressing reason to go wandering after wolverines. To use a phrase that sounds shopworn because the words apply to so many life forms these days: The animals are in serious trouble.

Still fairly widespread in the far North, Gulo gulo was also common across northern states from Washington to Montana during the 19th century and occasionally reported from the Great Lakes to New England. Its range continued south along the Pacific Coast range and Sierras far into California and all the way down the Rockies into Colorado and New Mexico. Today, the wolverines of the Lower 48 are confined to a few remote parts of Montana, Idaho, and northern Wyoming, with perhaps a….. dozen more in Washington’s North Cascades. They total no more than 500 and more likely number just 300 or fewer. To make a point about their present status, you could cram all of them into one person’s mountainside trophy home. It would be a snarlfest, but they’d fit.

Part of the predicament for this hunter-scavenger is that it has proved so hard to find and follow that much of its existence remains a blank. The public scarcely knows what a wolverine actually is apart from cartoon versions and trappers’ yarns about the beast. Unfortunately, natural resource managers don’t have much more to go on when deciding how best to promote the species’ survival.

Adding to the urgency is the current rate of climate change. What little was known about the range of wolverines made it plain that they are tied to environments with fairly heavy snowfall and cool year-round temperatures. In southern Canada and the Lower 48, that translates into a number of small, widely separated subpopulations in the alpine and subalpine zones of high mountain ranges, rather than a single continuous population.

To endure over time, though, the animals are going to need wildland corridors that guarantee individuals the freedom to roam from one chain of peaks to the next. As wolverines struggle to adapt to changing weather and shifting habitats in the warmer years to come, linkage zones running in a north-south direction may prove especially vital. Yet before ecologists can identify the best routes – the wildways that hold the most promise for keeping groups connected – many more gaps in our knowledge of the species’ natural history have to be filled in.

Except for mating, male wolverines were said to be strictly solitary – too volatile and vicious to tolerate company of any kind, least of all male company. Females were held to be equally short-tempered and unsociable apart from the six months during which they reared their kits. After that, the young were supposedly on their own. Yet from tracking radio signals on other days, I’d already gathered evidence of older juveniles spending time with their mother now and then. I’d also found M1 traveling with one of his mates outside the breeding season – more than once, suggesting that the pair maintained a long-term bond with each other.

Now I was documenting the case of a year-old youngster, already adult size, that had left its mother and gone on to hang out with Dad for a while – a sort of wolverine version of joint custody. What kind of mammal does that? None that I knew of other than Homo sapiens. What seemed odd was that in the 21st century we understood so remarkably little about one of the most intriguing creatures to ever walk the wild.

Pages 60-61:

The hallmark of our particular era is the startling pace at which humans multiplied to the point of monopolizing much of the biosphere and altering its basic qualities. When Glacier Park was established in 1910, it had about 150 glaciers. Today, with human activities spewing carbon dioxide and methane as if we were intent on re-creating Earth’s ancient atmosphere, a warming climate has reduced the number of glaciers to 25, and those are shrinking three to four times as fast as they were just half a century ago. The last one is expected to vanish by 2020.

I still don’t really understand what makes wolverines tick. But I learned that they tick at a higher metabolic rate than other animals their size. If you were to picture them as organic cruising machines with a souped-up carburetor, you wouldn’t be far off the mark. To hold in the heat of this internal engine, wolverines, like many northern mammals, wear a double coat – a dense inner layer of air-trapping wool beneath a cover of stout guard hairs, which add extra insulation. Textured to resist absorbing moisture, the long guard hairs that drape from wolverines are not only close to waterproof but also excel at shedding frost.

A gulo’s crampon-clawed feet are enormous relative to its body, spreading its weight like snowshoes – a major advantage over most competitors and prey during the cold months. By contrast, long, harsh winters drain the energy reserves of hoofed animals postholing through the snow, leaving some dead to be scavenged and others weaker by the day, more easily overcome for dinner. In steep terrain like Glacier, heavy snowfalls also mean more avalanches, which claim their own share of mountainside grazers. If buried deeply, the carrion keeps like meat in an ice chest until it melts out for gulos to gorge on through spring and early summer. Many of the avalanches replace forests with vertical stripes and fans that start life over as meadows filled with wolverine summer snacks such as ground squirrels and voles. In addition, wolverines cache food in snowbanks and in boulderfields with icy water running underneath.

The list of adaptations that allow wolverines to make an ally of winter is impressive. Yet until scientists started to focus on climate change, no one gave much thought to how creatures with built-in snowshoes, a super-cozy fur coat, smoldering metabolism, and food cached in nature’s refrigerators are supposed to handle swimsuit weather in our ever-toastier Age of Industrial Exhaust.

Combined, these two key requirements – a deep, lingering snowpack suitable for denning plus low to moderate summer temperatures – largely define the wolverine’s native range. Since much of the continent north of about 50 degrees latitude offers suitably frosty environments, the species is fairly widespread in the arctic, the subarctic taiga, and portions of Canada’s boreal forest. Farther south, the animals have to go up in elevation to find heavy winter accumulations of snow, just as they must to reach more tolerable summer temperatures. This explains why the wolverines of the Lower 48 are confined mainly to western mountain regions. The species’ relationship to cold and snow is what ecologists term obligate – it can’t get by without these factors.

Wolverines are emerging as a far more sensitive and more important indicator of global warming than wildlife managers were aware of before. If you want to take this a step farther, you might even be justified in thinking of Gulo gulo as the land-based equivalent of the better-known polar bear.

Excerpts from Douglas Chadwick’s The Wolverine Way courtesy of Patagonia Books.

Species: Gulo gulo

Type: Weasel

Family: Mustelidae

Habitat: Arctic, subarctic, alpine, and boreal zones such as forests, grasslands, tundra, and rocky areas (e.g. inland cliffs, mountain peaks).

Range: Circumpolar: Canada, China, Estonia, Finland, Mongolia, Norway, Russian Federation, Sweden, and the United States.

Population Health: Decreasing, but classified under “Least Concern” according to the IUCN Red List due to its “wide distribution and remaining large populations.”

Estimated Population Size: Due to low density and wide distribution, estimates are extremely difficult. Combining conclusions from various recent studies, the worldwide population likely ranges between 15,000 and 30,000 individuals.

Size: Resembling a small bear, the wolverine is 26 – 36 inches long, excluding its bushy, 5 – 10 inch tail; shoulder height is 14 – 17 inches, and weight is 20 – 66 pounds.

Diet: Deer, sheep, small bears, rodents, hares, and other small burrowing mammals. Large portion of diet also comes from scavenged meat from carcasses of large mammals such as caribou and elk.

Additional Facts:

• The wolverine’s binomial name, Gulo gulo, comes from the Latin word gulo meaning glutton. It’s a fitting name; the wolverine has a voracious appetite and is known to devour even the bones and teeth of the animals it finds or kills. The wolverine can accomplish this feat thanks to its razor sharp teeth and powerful mandibles.

• During the 19th century, wolverine populations nearly disappeared due to hunting and other human activities like deforestation and recreational use of their habitats. But over the last few decades, they have been staging a comeback—many scientists expect large populations living in Canada and the northern United States.

• While the wolverine is the largest species of the land-dwelling weasels, it is much smaller than many of the other mammals within its territory. However, its size belies its strength and remarkable fearlessness—there is at least one reported story of a 30 pound wolverine attempting to steal a kill from a 400 to 500 pound black bear!

• The wolverine’s sense of smell is uncanny—it can detect a carcass lying 20 feet under the snow, allowing it to find the remains of animals killed in avalanches.

• A solitary and nocturnal hunter, the wolverine spends most of the year by itself, roaming its enormous territory, which varies from 65 km in Montana, USA to over 600 km in Scandinavia.

• Wolverines were once thought to be entirely reclusive and anti-social, getting together only for the purpose of mating. However, new findings indicate that after infants are born, they stay with their mother for up to an entire year and the dad returns periodically to help raise the kits. It turns out wolverine dads like to show their offspring the ropes.

• Wolverines have an average life expectancy of 4 to 6 years, but some can reach up to 13. They come to sexual maturity around 2.5 years and mate during the spring and summer months with new litters of 1-2 infants, sometimes as many as 5, being born between February and April.

• Weighing only 30 pounds, the wolverine’s proportionally enormous paws act as snow shoes, allowing it to move quickly over snow covered areas. While this gives wolverines a huge advantage over their competitors, it also makes them highly vulnerable to climate change. Snow, in other words, is crucial for their survival.

• Wovlerine paws not only act as show shoes, but also double as claws, with the tip of each of its twenty toes curved and extremely sharp. Equipped with these hook-like extremities, the wolverine possesses what might be called natural crampons, which allow it to scale an ice fall or a sheer cliff with little difficulty.

• Not only do wolverines use snow to their advantage when hunting, they also build snow dens in which the kits are born and nursed. Because reproduction occurs during spring, this requires that snow cover persists well into February and March. Climate change, however, will likely bring spring temperatures earlier in certain areas, which poses another risk to the wolverine’s survival by further limiting its range.

• When female wolverines build their dens in late February, they dig as deep as 15 feet below the snow to protect their young from predators and the cold.

• Wolverines are perhaps best known for their attitude. They don’t hesitate to fight with wolves and other predators over a meal, and given the right snow conditions are even capable of taking down a moose—a feat wolverine specialist Doug Chadwick likens to “a house cat bringing down a deer.”

• In 2009, a wolverine named M56 was captured near Grand Teton National Park. Scientists tracked M56 using radio equipment and were astonished by its journey—it traveled 550 solitary miles during April and May, over highways, mountain ranges, and across state lines. M56 became the first observed wolverine in Colorado since 1919.

• The wolverine has a great deal of spiritual significance for Native Americans. For some, it functions as a link to the spiritual world and is understood as both a trickster and a hero.

• Wolverines are known for having a very strong odor. They use their pungent smell in order to mark their territory and ensure that no rival wolverines invade their range.

• Because wolverines are both extremely territorial and highly sensitive to disturbance, the increasing popularity of winter backcountry recreation combined with new and more powerful snow machine technologies suggests that wolverine range will continue to diminish to due human activity.

• Wolverines are notoriously difficult to study in the wild, which is why so little has been known about them. Scientists are only just beginning to put together an accurate picture of this marvelous creature by combining a number of research methods such as radio-tracking, remote camera surveys, live traps, and DNA traps.

Northern Rockies Conservation Cooperative – Wolverine Ecology
http://www.nrccooperative.org/
Organization dedicated to the conservation of species, ecosystems, and human communities

Glacier National Park
http://www.nps.gov/glac/

Wildlife Conservation Society – Wolverine
http://www.wcs.org/saving-wildlife/other-carnivores/wolverine.aspx
Organization conducting Yellowstone wolverine study

Kroschel Films Wildlife Refuge
http://kroschelfilms.com/
Steve Kroschel’s center in Haines, Alaska

The Wolverine Blog
http://egulo.wordpress.com/

Wolverine Network
http://www.wolverinenetwork.org/
Researchers, educators, advocates, and other citizens passionate about wolverines in the western U.S.

International Union for the Conservation of Nature (IUCN) Redlist of Threatened Species
http://www.iucnredlist.org/apps/redlist/details/9561/0

Copeland, et at., “The Bioclimactic Envelope of the Wolverine: Do Climactic Constraints Limit its Geographic Distribution?”
http://www.fs.fed.us/rm/pubs_other/rmrs_2010_copeland_j001.pdf
US Forest Service document

Central Idaho Wolverine – Winter Recreation Research Project
http://www.rmrs.nau.edu/wildlife/forest_carnivores/wolverine/
Study by the Rocky Mountain Research Station

A Humane Nation
http://hsus.typepad.com/
Blog of Wayne Pacelle, President and CEO of The Humane Society