MAZAMA — Six years after initiating the first wolverine study in the Pacific Northwest, Keith Aubry has been able to confirm that these elusive animals not only visit the North Cascades, but also breed and reproduce here.

The research biologist got that confirmation a couple weeks ago, after flying over their snow-covered territory and finding and photographing not one, but two remote natal dens where Xena and Mallory were holed up to have kits. A remote video camera later caught Xena with a kit in her mouth.

Another video camera is now trained on Mallory’s natal den to capture her the moment she moves her kits to what’s called a maternal den. Aubry said wolverines usually have a second den within about 200 meters, where they move after weaning their babies and are ready to leave them in the den while they go out to hunt and gather food.

“This is something we’ve been waiting for for a long time,” said Aubry, who is heading the study through the U.S. Forest Service’s Pacific Northwest Research Station in Olympia. “One of the primary goals of our study is to determine whether or not they’re really residents, and are reproducing and part of the fauna here,” he said.

That question has now been answered.

Aubry and his researchers didn’t just happen upon these dens. Each winter since 2006, they’ve set up traps with bait, and captured and radio-collared wolverines who climbed inside for an easy meal. The study team is alerted when an animal is inside the cage, and they head there on snowmobiles to measure and fit radio collars on the animals before releasing them back to the wild. The collars give biologists an idea of where the wolverines are traveling each day, and, in this case, where they’re hanging out.

This winter, Aubry said, they captured five wolverines, including three they’ve caught before: Xena, Mallory and Rocky.

By looking at their radio signals, it became clear that Xena was frequenting an area south of state Highway 20, and Mallory was staying in an area north of state Highway 20. So two Methow Valley biologists who are working with Aubry went to those areas by helicopter. They could see multiple tracks and a hole that appeared to be Xena’s den, so they landed and trained a camera on it.

They took photos from the air, but did not land near Mallory’s den until later, when they set up two video cameras.

Aubry said he went back a week later and retrieved the video. “We landed in this pristine, gorgeous snow-covered valley, and going right down the middle of the valley was a set of very large wolverine tracks,” he said.

Immediately, he thought those tracks belonged to Rocky, a male that had been previously captured, and caught again this year. His radio signals indicated he regularly visited both Xena and Mallory, and is the likely father to any of their kits.

He said before they even viewed the video to learn that Xena had moved her kit, they saw his tracks going right by her natal den, and into a stand of trees that was 200 to 300 meters from the first.

“Clearly, he knew that she had moved the kit. He must have passed by the old den, but didn’t even make a jog in that to go to what we think is the maternal den, where Xena has moved to begin feeding her kit solid food.”

Aubry said now that he has cameras set up on Mallory’s natal den, he plans not to disturb either of the wolverine mothers for at least a month.

Then, they’ll go back to the dens to collect their remote cameras along with hair and scat, if they can find it, for DNA analysis.

That could give them a profile of the wolverine babies, in case they capture them in a trap another year.

He said additional funding from the U.S. Fish and Wildlife Service, the Forest Service and the Wolverine Foundation will help them continue the study this summer.

He said the data could help discover what wolverines need to continue to thrive in the North Cascades. “We’re still learning what wolverines do in this area, and whether it differs in any way from wolverines in the Rockies,” he said.