With the click of a shutter on a motion-detecting digital camera, the secret was out.

The wolverine, long thought to have been driven from the forests of California, was caught on camera, calmly eating food from the forest floor several miles north of Truckee.

Scientists thought the elusive, but fierce, forest carnivore had been forced out of the Sierra Nevada long ago by human activity.

That's why the simple image, taken just after 8 a.m. Feb. 28, is shaking up the wildlife research and environmental communities. The picture of the furry black creature with a distinctive almond-colored stripe on its back is, researchers say, undeniably a wolverine.

"When I first saw the picture, it was amazing," said William Zielinski, a research ecologist with the Forest Service's Pacific Southwest Field Research Station. "I couldn't even conceive the implications of this discovery. I couldn't believe that this was before my eyes."

The sighting could also have major implications for land-use decisions if the wolverine is declared an endangered species, a step the U.S. Fish and Wildlife Service is considering.

"You can probably compare this discovery to James Marshall finding gold in California," said Steve Martarano, spokesman for the California Department of Fish and Game.

In the early 1920s, the high country of the southern Sierra Nevada was the California stronghold for wolverines, Zielinski said. The secretive animals tend to prefer rugged, isolated wilderness to areas more populated and influenced by humans.

But even 80 years ago scientists and biologists believed the threatened wolverine population was on the decline.

"The discovery is still sending shockwaves through the community of biologists who, like myself, believed for decades that there was never going to be a wolverine in California again," Zielinski said.

The picture, taken from behind the wolverine digging in the snow to feast on bait, poses many questions.

"It would be wonderful to understand what the origin is of this animal," Zielinski said. "It just showed up out of nowhere."

Katie Moriarty, a graduate student at Oregon State University, is the person behind the camera. And she was looking for American martens - not wolverines.

Moriarty was doing field work for Zielinski's study on the effects forest management has on martens. About 20 to 30 cameras were placed in the forest surrounding the Sagehen Creek Field Station, located 8 miles north of Truckee off of Highway 89 north. Moriarty checks the cameras on a weekly basis and went through the images on this particular camera last Sunday.

She said that when she saw the wolverine in the picture early last Sunday morning, it was a "complete shock. It was not something I would expect by any means."

"Moriarty was obviously surprised by what she saw and had a hard time conceiving what she was looking at," Zielinski said, who viewed the picture in an e-mail Sunday morning. "But she couldn't make it into anything else."

There are three possible answers to the wolverine's mysterious appearance, Zielinski said.

Taking into consideration the animal's capacity to roam across vast distances - both males and females cover ranges of more than 100 square miles - it's possible the animal migrated south from the Cascade Mountain Range in Washington state, or the Northern Rockies in Idaho or Montana - where small populations of the carnivore are known to exist.

The wolverine could also be a remnant of a small population in the Southern Sierra Nevada that has evaded detection for the past 80 years.

Or it could have escaped or been released from a captive facility somewhere.

All three are equal possibilities, and scientists are hoping to solve the puzzle by collecting samples from the animal - hair or scat - and piece together a solution to this mystery genetically.

"This is an exciting research discovery," Tahoe National Forest Supervisor Tom Quinn wrote. "For now, we at the Tahoe National Forest have more questions than answers."

The U.S. Forest Service and researchers have started discussing where this sighting occurred and how it could affect management of the National Forest.

"As we learn more, we will assess which projects and activities, if any, might be affected," Quinn wrote in the statement.

Martarano said there have been repeated efforts by the California Department of Fish and Game since the 1990s to document the existence of wolverines in California. But none have been successful.