MAZAMA, Okanogan County — 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 here.

The research biologist got that confirmation a couple weeks ago after flying over their snow-covered territory and finding and photographing two remote natal dens where two females, dubbed Xena and Mallory, holed up to have kits. A remote video camera later caught Xena with a kit in her mouth.

Another 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. He 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.

"This is something we've been waiting 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."

That question has now been answered.

Aubry and his researchers didn't just happen upon these dens. Each winter since 2006 they've captured and radio-collared wolverines and released them back to the wild. The collars give biologists an idea of where the wolverines travel and hang out.

It became clear that Xena was frequenting an area south of Highway 20, and Mallory north of Highway 20. So two 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 aimed a camera at it.

They later landed near Mallory's den and 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 who had been captured previously 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.

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 the researchers will go back to the dens to collect their remote cameras along with hair and scat, if they find it, for DNA analysis.

Aubry said the data could help biologists learn what wolverines need to continue to thrive in the North Cascades.