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The last time anyone saw one of these critters in Utah was 35 years ago when a roadkill carcass was found along U.S. Highway 40 east of Vernal.

But last winter a motion-sensing camera, one of four rigged on the Uinta Mountains' north slope, captured 27 images of a wolverine sniffing around an empty bait station, according to the Utah Division of Wildlife Resources (DWR).

The find, made in the Blacks Fork drainage in Summit County, was announced Wednesday, one month before the U.S. Fish and Wildlife Service is expected to decide whether to list this rare predator under the Endangered Species Act. The animal was largely eliminated from its range in the lower 48 states by the early 20th century, due to trapping and poisoning campaigns targeting predators.

Although wolverine tracks have been confirmed in the Uintas in recent years, DWR officials aren't ready to say whether wolverines have re-established a presence in Utah's northern mountains. This is because wolverines have home ranges up to 1,000 square miles and males are known to roam for miles outside those ranges.

"It could be an animal that passed through the area and has since moved on, never to be seen again," mammals conservation coordinator Kim Hersey said.

Utah State University wildlife biologist Mike Wolfe also cautioned against rushing to conclusions. He suspects lone male wolverines have been passing unnoticed through Utah for years, pointing to photographs of tracks taken by one of his graduate students.

To prove the species has re-established itself, "you need to have multiple sightings in a relatively small area in a short time frame," said Wolfe, a professor emeritus. "The best thing would be where you had a female with cubs."

News of the photos still excited conservationists.

"I am ecstatic. It proves the return of the wolverine to Utah and the Uinta Mountains and it will have an impact on motorized recreation and logging in the Uintas," said Kevin Mueller, Southern Rockies conservation manager for WildEarth Guardians. "No matter how you cut it, those are additional impacts to a species that is extremely sensitive to disturbance."

He argued the wolverine photographs provide new and significant information that should give the Uinta-Wasatch-Cache National Forest pause before signing off on a timber harvest proposed on 4,400 acres in the Smith Fork, the drainage immediately to the east of Blacks Fork. A decision is expected to be issued as early as Thursday.

However, under a special proposed rule, Fish and Wildlife Service officials contend a wolverine listing would not affect timber harvests, snowmobiling, skiing or other human activities they say do not threaten the animal.

With little help from human intervention, wolverine numbers have rebounded in the North Cascades and Northern Rockies, but there are still only 250 to 300 individuals. Scientists now fear climate change will render much of their southern range uninhabitable. This is because wolverines are restricted to alpine environments where temperatures are cold year-round and snow cover persists through May.

Still, in recent years, a wolverine fitted with a radio collar has appeared in Colorado and Utah's DWR fields five to 10 "credible" annual sightings.

"Even where they are known to be established," Hersey said, "it is incredibly rare to see one."

In hopes of recording wolverines, lynxes and other elusive predators, DWR biologist Adam Brewerton put out four cameras last January, with the help of U.S. Forest Service biologists. Locations were selected based on past unconfirmed sightings.

They hung roadkill deer from trees in the cameras' lines of sight. Brewerton recovered the cameras in recent weeks after the snow melted and pored over the 40,000 images they shot. The camera set up in Blacks Fork recorded marten, jays, squirrels and finally a red fox raiding the bait station.

On Feb. 18, two days after the fox took off with the carcass, the wolverine appeared around 6:39 p.m. and hung around for five minutes, checking out the empty cage. Two months later, another trail camera to the north in Wyoming, about 20 miles from Evanston, recorded a wolverine. Biologists are trying to determine if the photographed animals are the same individual.

"If it is, we can determine a time frame when the animal or animals may have been in the area," Brewerton said. "We can also determine if the wolverine was wandering through the area or if it's a resident animal that's making its home here."