Excitement over rare red fox sighting in Yosemite

A Sierra Nevada red fox was captured by a motion activated camera in the northern part of Yosemite National Park. A Sierra Nevada red fox was captured by a motion activated camera in the northern part of Yosemite National Park. Photo: Motion Detection Camera / Yosemite National Park Photo: Motion Detection Camera / Yosemite National Park Image 1 of / 1 Caption Close Excitement over rare red fox sighting in Yosemite 1 / 1 Back to Gallery

Wildlife biologists are giddy after their motion-activated cameras captured a rare Sierra Nevada red fox loping through the forests of Yosemite National Park.

When cameras spotted the fox on Dec. 13 and Jan. 4 in the remote northern section of the park, it was the first confirmed detection of the species in Yosemite since 1916, said Sarah Stock, a wildlife biologist for the National Park Service.

“We are pretty excited because, if you look at the confirmed evidence in the park, there was every reason to believe they had disappeared,” Stock said. “Confirmation of the Sierra Nevada red fox in Yosemite National Park’s vast alpine wilderness provides an opportunity to join research partners in helping to protect this imperiled animal.”

Slaughtered for fur

The Sierra Nevada red fox is one of the rarest mammals in North America. The native foxes, known as Vulpes vulpes necator, prefer high-elevation alpine regions and were once abundant throughout the Sierra range.

But their lush, warm coats and bushy tails were coveted by fashionable women and fur coat manufacturers in the 19th and early 20th centuries, leading to their wholesale slaughter by trappers.

It didn’t help that most predators were considered vermin at the time and shot on sight — even by those who didn’t care about their coats. Geneticists believe there are now fewer than 50 Sierra Nevada red foxes left in California.

A decision by the U.S. Fish and Wildlife Service is expected this fall on whether to accept a petition filed in 2011 to list the foxes under the U.S. Endangered Species Act.

Stock said she and her colleagues suspected the foxes might be living in Yosemite after a small population was discovered in 2010 in the Sonora Pass area, just north of the park border. Six motion-sensitive cameras were set up over the winter, and a party of backpacking biologists recently retrieved the photos.

The Sierra foxes look similar to, but are genetically distinct from, non-native red foxes imported from Alaska in the early 20th century for their fur. Thousands of these Alaska foxes can be found, mostly in lower elevations like the Central Valley, but Stock said they have recently been moving higher as the weather has warmed and high-elevation snow has decreased.

“One of the threats to the Sierra Nevada red fox is hybridization with the non-native red fox,” Stock said. “That actually has occurred as the non-native red fox has expanded its range into higher elevations. My job is to protect biodiversity, so when we have a subspecies like this that has its own unique genetic makeup, it’s important to protect it.”

Safer in Yosemite

Stock doesn’t know how long the Sierra foxes have been coming into Yosemite, but she said it’s a good move as they won’t be threatened by logging, livestock grazing or recreational activities like snowmobiling that occur outside the park.

Park biologists, whose work is funded by the Yosemite Conservancy, plan to work with researchers at UC Davis, the California Department of Fish and Wildlife and the U.S. Forest Service to document the numbers and movements of the Sonora Pass and Yosemite fox populations. Stock said hair-snare stations have been set up in an effort to obtain fox hair samples for genetic analysis.

Peter Fimrite is a San Francisco Chronicle staff writer. E-mail: pfimrite@sfchronicle.com Twitter: @pfimrite