Rare red fox sighting in Yosemite: Bless skunk glands and automated cameras

Give credit to road kill, skunk glands and automated cameras. The strange-sounding combination helped Yosemite National Park get its first documented sighting of a rare Sierra Nevada red fox in 99 years.

The proof is a photograph from an automated camera of a red fox lightly treading on a blanket of snow — perhaps lured by tasty deer road kill or the scent of skunk glands hung on a tree by biologists.

In media all over the globe, the fox’s image was displayed last month and hailed as the return of a near-extinct animal in California’s most celebrated wilderness where it would be protected from development, snowmobiles and a host of other activities.

This was a feel-good story linking to a Yosemite era when sightings of such iconic species as the bighorn sheep and the wolverine were last documented.

“The symbolism of the Sierra Nevada red fox coming into Yosemite is powerful,” said park wildlife biologist Sarah Stock. “We haven’t seen one here since 1916. A national park can protect this species.”

But it also was a triumph of wildlife biology and camera gadgetry. Biologists knew where to look and how to attract the elusive fox. Motion-triggered cameras watched day and night. Otherwise, this critter might have passed unseen in Yosemite for years.

The red fox, a striking wisp of a mammal weighing about 8 pounds, may have been wandering into the rugged north country of Yosemite for some time. Nobody knows for sure how long. Only in the last two decades have researchers been able to make a serious search across the 400-mile Sierra Nevada for the estimated 50 red foxes still alive.

Though the red fox can be found around the globe and throughout the United States, the Sierra Nevada red fox is a mystery, avoiding people and struggling almost in secrecy to survive against forces that scientists have not been able to identify.

Researchers do not know what is holding down their numbers — disease, predation, lack of food, climate change, toxins, grazing, development, recreation?

Researcher John Perrine, an associate professor at California Polytechnic State University at San Luis Obispo, was among the authors of a 2010 study assessing the only known group of these animals at the time in Northern California’s Lassen National Forest.

“Trapping was outlawed in 1974,” Perrine said. “But there was never a lot trapping. There is still a lot of habitat. It’s not really clear yet what is happening.”

The fox, which many feared had been completely wiped out in the Sierra, is protected under the state Endangered Species Act. Federal officials are considering similar protection under the federal version of the act, and a decision may come later this year.

Living in the wilderness, the red fox eats mice, ground squirrels, wood rats, chipmunks and rabbits. It also scavenges livestock carcasses. Decades ago, research relied mostly on interviews with few eye witnesses, such as trappers.

The red fox lives at an elevation of 9,000 feet, where trees begin to disappear in the Sierra, biologists said. The fox once lived throughout the Sierra from Tulare County to Sierra County and well into the Cascade Range.

A few years ago, scientists discovered a group of red foxes living in the Stanislaus National Forest near the Sonora Pass area just north of Yosemite. The scientists knew there was a chance the foxes were straying into nearby Yosemite, said researcher Cate Quinn from the University of California at Davis, who is focusing her doctoral dissertation on the animal in the Sonora Pass area.

Quinn said she and others are trying to get a baseline of information about the red fox — how many are in the area, how far are they ranging, what are the obstacles to expanding the population?

She said the biggest threat to this mountain red fox is the small population size. Disease or a catastrophic fire, such has the Rim fire in 2013, could easily kill them all. That’s why it is important to learn as much as possible about the estimated 30 foxes living around Sonora Pass, she said.

“In mid-January we trapped a female and put a radio collar on her so we can track movements now,” Quinn said. “They’re very difficult to catch. They’re attracted to deer meat and chicken, but it’s very hard to get them to actually step into the trap.”

The scientists also try to get hair samples, which can be DNA tested to establish separate individuals in the group.

In Yosemite, biologist Stock said the bait is sometimes deer meat from road kill. Researchers also use ground anal glands of a skunk to lure the red foxes. The lures helped bring a red fox into a place where the automated camera could capture its image.

“The skunk glands are all about territoriality,” Stock said. “The red fox is very curious about scents. The hair snares used to get hair samples that basically look like a bottle brush sticking out from a tree below the lure.”

Perrine said the cameras used to photograph in the wild “are no more sophisticated than the motion-detector light in your back yard. It’s just a matter of putting the technology in the right place.”

Scientists would love to see any Sierra Nevada red fox photographs that hikers or backpackers might take in the wilderness.

Photographs are important for confirmation of a sighting. It is often difficult, even for those with a trained eye, to distinguish a fast-moving red fox from a gray fox or even a coyote.

Quinn of UC Davis said one of the keys is the tail: The red fox’s tail is nearly as long as its body, and it is white-tipped. Also, the back of its ears are black.

The gray fox and the coyote have a black-tipped tail and orange coloring at the back of the ear. The coyote also has a shorter tail than foxes.

People in the flatland of the Central Valley might also be confused by a sighting of a different red fox species, called the Sacramento Valley red fox.

There was no mistaking the animal in the photograph released by Yosemite last month, Perrine said.

“It was like a glimpse of true wilderness,” he said. “It’s such an important part of our natural heritage in California.”

This story was originally published February 23, 2015 at 5:00 PM with the headline "Rare red fox sighting in Yosemite: Bless skunk glands and automated cameras ."