Wildlife advocates are thrilled to document a breeding female wolverine south of I-90 for the first time in modern times. The carnivore is a cherished commando of the forest realm, and a master of its landscape.

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The first breeding female wolverine has been documented south of Interstate 90 in modern times, confirming a comeback for the charismatic carnivore in the Cascades.

Renowned for their agility, power and all-terrain finesse, wolverines are among the most rare mammals in North America.

A denizen of deep snows, capable of traveling hundreds of miles in conditions that send other land animals into hibernation, wolverines were extirpated in Washington by over-trapping, and shot on sight as vermin, like most other predators in the 1900s.

Remnants of Washington’s native wolverine population retreated to Canada. From there, they have begun a slow recolonization of their native habitat in Washington, starting with the North Cascades.

The sighting of the breeding female indicates they may be extending their range into the south Cascades.

“This is showing that wolverines are able to expand into more of this historic distribution that has been unoccupied since the 1930s,” said Jocelyn Akins, a wildlife biologist and conservation director of the Cascades Carnivore Project, a nonprofit formed to monitor rare carnivore populations in the Cascades.

Wolverines used to range along the Cascade Crest but today remain exceedingly rare, with perhaps just 25 animals in Washington and only about 250 to 300 in the entire Lower 48.

Also called the skunk bear for their striped coat, wolverines (scientific name “Gulo gulo,” or the “gluttonous glutton”) are solitary, secretive and furtively avoid humans, keeping to remote, wild places.

Pound for pound, they are among the most ferocious carnivores in Washington, capable of sniffing out frozen carcasses and tunneling through feet of snow to crack open bones and tear apart even frozen carrion. Their powerful jaws and molars are specially adapted to shear off chunks of rock-hard flesh and bone.

“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. Climb everything … eat everybody. Alive, dead, long dead, moose, mouse, fox, frog, it’s still warm heart or frozen bones,” writes Doug Chadwick in his book, “The Wolverine Way.”

Their long, thick, brown and gold coat sheds frost and is underlaid with a soft insulating layer of fur that lets the wolverine shrug off the most brutal cold. Sharp, semi-retractable claws make them the superheroes of the wild, able to scrabble up and down trees and rocky slopes.

Weighing in at about 30 pounds, they are the largest of the weasel family on land; sea otters are in the same family and outweigh them in the water.

Female wolverines come into mating season only about once every two years. When not seeking a mate, they are solitary creatures.

Tracking wolverines requires near heroic effort. Using remote, motion-triggered cameras, the Cascades Carnivore Project has been able to snag hair for DNA analysis and photographically document the presence of the same female south of the Cascades beginning in 2016. The discovery this spring that she is lactating demonstrates she is reproducing, great news for an animal persisting in such small numbers.

Photos were taken of her east of Mount Rainier on the Naches Ranger District, in the William O. Douglas Wilderness.

The female is known to be the same one seen earlier, because each wolverine has a unique blaze of fur on its chest, making photo identification possible.

A male was also documented in the same area, probably her mate.

“It’s a big deal,” said Patty Garvey-Darda, wildlife biologist with the U.S. Forest Service on the Cle Elum Ranger District of the Okanogan National Forest. “Nobody knows for sure, but it appears maybe they have expanded their range.”

Charlie Raines, director of the Cascade Checkerboard Project with the Sierra Club, a long-running project to protect and connect wild lands in the Central Cascades, said protection and reconnection of vast swaths of wild country can only help the recovery of the wolverine, an animal that needs lots of space to roam.

Seeing wolverines in more of their traditional territory is a good sign that those efforts are paying off, Raines said.

“It shows when you protect and restore the habitat and provide connectivity, these wild creatures will re-inhabit their original range. This is good news. We need some more of that.”

The Washington Department of Transportation is nearing completion of an overpass by this fall for wildlife at I-90. It will enable animals like the wolverine to cruise the landscape north and south of the freeway in search of food, mates and denning habitat.

Under-crossings along the freeway just east of Snoqualmie Pass at Gold Creek are already completed and being used by all sorts of animals, large and small, terrestrial and aquatic. Even pika got a break, with piles of rocks put along the crossings just for them.

The crossings are part of a historic effort in Washington, documented in a new film, to improve 15 miles of I-90 for wildlife passage, in addition to widening the road for motorists.

Garvey-Darda said if even rare animals like the wolverine use the crossing, that is a signature of success. “Building these over-crossings and under-crossings will give us a lot more assurance that we can keep viable populations of wildlife in the Cascades,” said Garvey-Darda, liaison to WSDOT on the crossings project.

The over-crossing is expected to be particularly helpful to wolverines, she said.