Cascades wolverine population growing, expanding southward

Last week, we got some news that that made everyone in our office smile: Washington State Department of Transportation (WSDOT) biologist Josh Zylstra and Okanogan-Wenatchee National Forest biologist Aja Woodrow found probable wolverine tracks just eight miles north of I-90.

Not only is this the furthest south that wolverines have been documented in the North Cascades (the area from I-90 in Washington to Canada’s Fraser River Valley) since they were confirmed back in our state, but it is also exactly why we’ve worked so hard to create safe passage for wildlife under and over the busy interstate.

The wolverine tracks, found in the upper Cle Elum River drainage, come on the heels of wolverine photos captured by Woodrow in December 2014. Those photos came from trail camera locations further up the Cle Elum River watershed and in the nearby Teanaway River drainage, locations northeast of where the wolverine tracks were found last week.

Wolverines are intrepid travelers, capable of covering many miles through rugged and snowy terrain, so it’s possible these sightings represent the movement of one individual wolverine.

If this wolverine is able to successfully expand its territory south of I-90, it might be the start of a vital link between the growing wolverine population in the North Cascades and individual wolverines documented in the Central Cascades (the area from I-90 south to the Columbia River). This southward expansion could also jump-start the species’ recovery in Mount Rainier National Park and the Gifford Pinchot National Forest.

A number of other wolverine sightings were confirmed across the North Cascades in 2014, evidence that this population is likely growing and expanding it’s range southward.

In August, hiker Jake Gentry captured astonishing photos of a wolverine near the Spider Gap trail north of Lake Wenatchee, delighting outdoor recreationists, conservation organizations and the local media.

Conservation Northwest’s Citizen Wildlife Monitoring Project also documented four individual wolverines during our recent Spring-Fall 2014 monitoring season, including at locations north of Stevens Pass and in the Chiwaukum Range west of Leavenworth. Hair samples collected at these monitoring sites are being tested to determine if they represent a new generation of wolverines in the North Cascades, or if they are individuals previously documented.

Cascades wolverines recovering, threats remain

Researchers have called the wolverine “the superheroes of the animal world.” As biologist Doug Chadwick puts it in his book The Wolverine Way, “If wolverines have a strategy it’s this: Go hard, and high and steep and never back down. Not even from the biggest grizzly and least of all from the mountain.”

Once shot on sight, trapped and poisoned as vermin, wolverines were thought to be locally extinct in Washington by the 1930s. But in recent years Gulo gulo, a member of the weasel family the size of a small Labrador retriever, has been making a comeback in the North Cascades under state protections from hunting and deliberate trapping. Genetic data from “hair snares” has linked Washington’s resurgent population to wolverines in Canada.

Today biologists believe Washington’s North Cascades wolverine population consists of less than three dozen animals, with only around 300 wolverines remaining across the lower 48 states. A lone wolverine was also documented north of Mount Adams and in the Goat Rocks Wilderness area in 2009, but no wolverine population has been confirmed in Washington south of I-90.

Nationally, the U.S. Fish and Wildlife Service (USFWS) proposed listing the wolverine under the Endangered Species Act (ESA) in 2013. However, that proposal was withdrawn in 2014 at the request of state officials in the Northern Rockies opposed to the ESA listing.

Conservation groups, including Conservation Northwest, have sincefiled an intent to sue notice with the USFWSfor its refusal to protect the species under the ESA, citing that the agency disregarded well-established scientific evidence, including the recommendations of its own scientists, in refusing to protect wolverines.

Though wolverines are renowned for being bold and ferocious, they are primarily carnivorous scavengers, feasting on a wide variety of foods, including carrion from winter-killed deer, elk and mountain goats. They will also hunt small mammals, including pikas, marmots, ground squirrels, porcupines and snowshoe hares, as well as eat bugs, berries, eggs and roots.

Wolverines are generally extremely wary of people and do not pose a risk to hikers or backcountry travelers.

Though they’re making a comeback in our region, these elusive creatures have slow reproductive rates and are highly dependent on protected mountain habitats, large wild territories, and a deep snowpack that persists well into the spring for their breeding dens. While they occupy an important niche in the mountain ecosystem, wolverine populations are slow to recover from threatened levels, and are notoriously difficult to study.

Wolverine research ongoing in the Cascades

Biologists like Woodrow and Zylstra, as well as researchers from the Washington Department of Fish and Wildlife (WDFW), Woodland Park Zoo and our own Citizen Wildlife Monitoring Project (CWMP), are continuing to add to our knowledge about the resurgence these animals are making in the Cascades.

Researchers are hoping to better understand the distribution and abundance of wolverines in the Cascades said Woodrow. They’re also working to answer the question of “Does I-90 currently fracture the flow of wolverine genetics between the North and South Cascades? And if so, once the I-90 wildlife crossing structures are complete, will wolverine genetic connectivity be restored?”

The result of years of work by Conservation Northwest, the I-90 Wildlife Bridges Coalition, the Cascades Conservation Partnership, state, community and business leaders, and WSDOT, construction is now complete on three wildlife undercrossings at I-90 near Snoqualmie Pass. Construction on two overcrossings, or wildlife bridges, is fully funded and scheduled to begin this spring near Lake Easton. This important connectivity work is part of the state’s I-90 Snoqualmie Pass East Project.

When the project is complete, wildlife including elk, deer, wolves and wolverines will have access to numerous safe crossings under and over the busy interstate, connecting habitat in the north and central Cascades, promoting genetic interchange between animal populations, and protecting both wildlife and drivers from potentially deadly collisions.

Only time will tell if the wolverine documented last week just north of I-90 will find the new undercrossings at Gold Creek and Rocky Run this winter. If it does, WSDOT motion-activated cameras should be able to photograph the historic crossing.

Whether that happens this winter or sometime in the future, the recent sightings are evidence that the wolverine population in the North Cascades appears to be growing, and is expanding it’s range southward. 

If this recovery continues, it’s possible Washington’s wolverines could someday link up with wolverines in Oregon, where at least two wolverines exist in the Wallowa Mountains but the species remains unconfirmed in the South Cascades. Or even with wolverines in California, where at least one exists in the northern Sierra Nevada.

Return of a mountain icon

The elusive wolverine is an icon of North American wilderness — an animal that can scale steep, snow-covered mountains, dig dead mountain goats out of avalanche debris for food, fend off much larger predators, and travel hundreds of miles during the middle of winter. When most creatures are hunkered down in hibernation or have fled to the lowlands to wait for spring, the wolverine remains, lord of it’s mountain domain.

It’s easy to be inspired by these amazing creatures. At Conservation Northwest we’ve been rooting for them and working hard to support their recovery since they returned to the Washington Cascades in the mid-2000s. Today, we’re thrilled to see these indomitable Northwest natives reach a new milestone in their epic return to our region.