The discovery could affect land-use decisions if the wolverine is declared an endangered species, a step the U.S. Fish and Wildlife Service is considering, although the animals typically live at high elevations where there is limited development.
A graduate student at Oregon State University, Katie Moriarty, got a picture of a wolverine recently on a motion-and-heat-detecting digital camera set up between Truckee and Sierraville, in the northern part of the mountain range.
Moriarty was trying to get pictures of martens, which are slender brown weasels, for a project she was doing with the U.S. Forest Service's Pacific Southwest Research Station.
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."
News of the picture surprised scientists, who thought wolverines, if they still inhabited the Sierra, would be found only in the southern part of the range, not in the Lake Tahoe area.
There had been sightings of wolverines by reputable people but no solid proof they were still in the Sierra, said Bill Zielinski, a research ecologist for the Forest Service who was working with Moriatry.
"The conventional wisdom was that they were pretty much gone from California," said Zielinski. "There's been a lot of other camera work and a variety of methods used to track rare carnivores. Those same methods, if wolverines had been around, would have detected them, we thought."
Zielinski said he sent a copy of the picture to a colleague who is a wolverine expert and who verified that the animal in the picture "looks like the real deal." He also said he didn't think there had been any tampering with the picture before he received it.
"The student I worked with has the utmost integrity in these matters," Zielinski said. "This picture was in her control at all times. It went immediately from the camera to her e-mail and to mine."
Shawn Sartorius, a biologist with the Fish and Wildlife Service, said the wolverine could be a long-lost California native, an immigrant from Washington or Idaho or a captive wolverine that had been released into the wild.
"It would be fantastic if it's a real California wolverine because they are a genetically distinct group that was probably isolated at least 2,000 years and possibly 12,000 years ago," Sartorius said. "That would be a pretty important find."
He said scientists wanted to get a DNA sample from the wolverine in Moriarty's picture to determine its origin. That could be done by locating hair or feces left behind by the animal.
Paul Spitler, public lands director for the Center for Biological Diversity, an environmental group based in Tucson, Ariz., said his group gets reports of wolverine sightings "on a regular basis" in the southern Sierra.
"We know they are in the Sierra," he said. "We don't know how many and we don't know how far they travel in the Sierra, but we certainly know they exist in the Sierra Nevada."
The Fish and Wildlife Service is scheduled to announce Tuesday whether it plans to move ahead with the lengthy process of classifying wolverines as endangered.
