After a 99-year hiatus, the elusive Sierra Nevada red fox has been rediscovered in Yosemite National Park.
In January 2015, a pair of biologists at California’s Yosemite National Park trekked deep into the backcountry with one goal: find the Sierra Nevada red fox.
Yosemite staffers had previously set up motion-sensor camera stations near the park’s northernmost border, at around 10,000 feet, following a habitat suitability model from independent researcher Casey Cleve. The area is so remote that it requires a five-day trek round trip, and it was only when they got back to their tent after checking one of the cameras that the volunteers realized what they had.
“They just completely flipped out,” says Yosemite biologist Sarah Stock, describing the excitement of the biologists, who had reviewed the footage while in their sleeping bags. There, among hundreds of images, was the photograph that later would make so many headlines and rounds on social media: a crisp image of a lone Sierra Nevada red fox walking through the snow.
Back at park headquarters, Stock and a group of anxious co-workers relived the moment the next day as they listened to the news on speakerphone, their cheers resounding throughout the building. Stock checked their database and discovered that the sighting was even more rare than previously thought: The last time there had been confirmed evidence of the species inside Yosemite Woodrow Wilson was president — in 1916. “This is a major chapter in the conservation history of the species,” Stock says. “It also means a lot for the park.”
Native to California, the Sierra Nevada red fox (Vulpes vulpes necator) is a subspecies of the red fox — cousins of the Cascade red fox and Rocky Mountain red fox — and is known to live in the high peaks and ridges of the Sierra Nevada and Cascade mountain ranges. Since 1980, the fox, which has also been known to inhabit Oregon, has been considered “threatened” by the state of California.
The last major breakthrough concerning the animal happened back in 2010, when a group of researchers discovered a small skulk was living near Sonora Pass, some 12 miles north of Yosemite. The finding was monumental since, at the time, the only known Sierra Nevada red foxes existed in Northern California’s Lassen Peak region, and that population was dangerously small (perhaps 20 foxes total). Placing the red fox inside Yosemite’s boundaries didn’t come as a huge surprise to researchers, since there had already been detections near the border, but it does provide hope that there might be populations yet to be discovered elsewhere in California. It also serves as a crucial link to the heritage of the park, where other iconic species such as bighorn sheep have made a comeback.
“Similar in some ways to the wolves in Yellowstone National Park, you have this idea that this is part of the original functioning ecosystem,” says John Perrine, who is an associate professor at California’s Polytechnic State University at San Luis Obispo. “It’s a very rare part, but it’s still there.”
Having completed his dissertation on the population of Sierra Nevada red foxes in the Lassen Peak region, Perrine is quick to point out that, unlike the wolf, the red fox creates little controversy for area ranchers. Safety of livestock, such as chickens, is simply not an issue. It’s not that these foxes would not go after a chicken — in fact, chicken meat is one of the common baits used to lure the animals to the detection stations (along with cat food and road kill). It’s that they typically wouldn’t come in contact with one.
In his seminal 1937 work, Fur-bearing Mammals of California, Joseph Grinnell cites a local trapper who described the Sierra Nevada red fox as the “wildest wild creature,” with a “greater fear of man and his scent than all the other fur bearers combined.” Grinell writes: “Unlike the red fox of eastern North America, the red fox of California is rarely found in well-settled country or even anywhere near cultivated lands.”
Historically, farmers in California might have been interested in the red fox for another reason: its pelt. During the early 1900s, trappers sought out the animal for its prized fur. Interest was so high that the state started importing non-native red foxes via railroad — for both hunting and “fox farms.” But despite California’s ban on trapping and hunting of the foxes in 1974, the population has remained on the brink.
In 2013, the Center for Biological Diversity filed a lawsuit against the U.S. Fish and Wildlife Service for failing to protect the species. As of press time, the USFWS was still reviewing whether to include the fox on the federal “Endangered Species” list.
The reasons why the species has continued to exist in such small numbers are unclear. A 2010 ecology report from the U.S. Forest Service cited that threats could include habitat loss and fragmentation and diseases from domestic dogs. Ben Sacks, a geneticist with the School of Veterinary Medicine at the University of California-Davis who is collaborating with Stock on the issue, says their best guess is that inbreeding depression is what’s holding them back. Sacks has been studying the population near Sonora Pass and is considered the leading authority on the genetics of the animal.
Biologist Stock reads from a bullet-pointed list of possible culprits: “Logging, livestock grazing, fire suppression, climate change ... but none of these things we’ve really studied in depth,” she says.
Indeed, it is the lack of bona fide information on the red fox that could be its greatest threat. Perrine points out that no one in recent times has ever found a den, for example.
Over the years, officials at Yosemite have received a half-dozen reports of red fox sightings inside the park, but they all turned out to be unsubstantiated. Stock points out that some people mistake the gray fox, which is much more prevalent and can take on a reddish tint, for its rust-colored cousins. Sierra Nevada red foxes, which are about 8 to 12 pounds, can themselves appear to be silver or black in color. It is the distinctive white tip on their tail, however, that sets them apart from gray foxes and coyotes.
Stock says another distinguishing feature of the foxes is that they have found a niche in extremely high elevations, living in the high peaks and ridges of the Sierra and Cascade mountain ranges. “It is truly an alpine species,” says Stock, who adds that the now-iconic photo shows the horizon line of a ridge in the background.
Pete Figura, a wildlife biologist with the California Department of Fish and Wildlife, points out that the proliferation of modern digital cameras, which can record thousands of images and in some cases remain active for an entire year, is a major factor. Although the use of remote “trail cameras” is not new, situating the cameras in the deep backcountry is a relatively new practice.
Through Figura’s own camerawork in the Lassen region, he has been able to identify 18 individual foxes. And if they are shy around cameras, they are even more so around people. Figura himself, after seven years of fieldwork, has only ever seen one Sierra Nevada red fox alive in the wild.
Still, everyone seems to agree that it’s too early to use words like comeback or rebound in talking about the Sierra Nevada red fox. Perrine points to the old adage that “absence of evidence is not evidence of absence.”
“Really it’s an increase in our knowledge that they’re there, but it doesn’t mean that the population is increasing or recovering,” he says.
The Central Sierra Environmental Resource Center’s executive director, John Buckley, suggests that the fact that the foxes live in such extreme habitat is in part due to environmental stressors, such as competition from an ever-expanding coyote population, that have “rippled” all the way up into the crest zone.
“It’s one of these situations where lengthy in-depth studies are essential,” Buckley says, “yet waiting years to get the results from in-depth studies may mean it’s too late.”
But it’s also possible that the populations of native red foxes were never overly abundant in the first place. Figura says that, by all indications, the foxes were fairly rare as far back as 100 years ago in California.
What we do know is that the Sierra Nevada red fox, which Perrine associates with the “spirit of the West,” has persisted, and it’s done so in some of the remotest, most rugged terrain — in the rocky outcrops near the tree line.
In March 2015, another Yosemite crew went back to the same camera stations, and, much to their excitement, found that the same camera again had detected a red fox.
Stock says the next step will be to assess the population through hair samples, which they hope to obtain by using what are essentially bottlebrushes, and scat surveys. If researchers do get DNA evidence, she says, they will work with Sacks to analyze it.
For Stock, the latest sighting meant confirmation that earlier sightings weren’t the result of a fluke, but also meant hope. Knowing that the Sierra Nevada red fox calls Yosemite home means that conservationists have a better chance to protect it. Since some of the potential threats to the fox, such as effects from cattle grazing and over-snow vehicles, don’t occur inside the park, it might prove to be a valuable studying ground.
“We’re capable of destroying an animal,” Stock says, “but we’re also capable of bringing it back.”
From the January 2016 issue.