For the first time in nearly a century (!), a Sierra Nevada red fox has been sighted in Yosemite National Park.
Above: A photo of the Sierra Nevada Red Fox taken by Yosemite's motion-sensitive camera | Photo Credit: NPS Photo
Two photographs of the critically endangered animal were captured by motion-sensing cameras in the far-northern reaches of the park, once in December 2014, and again in early January of this year. The December photograph is featured here:
"We are thrilled to hear about the sighting of the Sierra Nevada red fox, one of the most rare and elusive animals in the Sierra Nevada," stated Don Neubacher, Yosemite National Park Superintendent, in a statement issued by the National Park Service.
Every bit as important as the sightings, themselves, are the photographs that confirm the fox's identity. In a conservation assessment published in 2010, U.C. Berkeley biologist John D. Perrine and his colleagues describe the history of red fox sightings in the park, and how difficult these sightings can be to verify:
Biologists at Yosemite National Park have received only ten red fox sighting reports since 1977, most of which occurred in or near Yosemite Valley... Unfortunately, sighting reports are notoriously inaccurate, and without a photograph or voucher specimen, it is impossible to confirm whether the sighting was of a red fox or some similar canid such as a gray fox or coyote.
Though they were once distributed throughout the Sierra Nevada, the southern Cascades in California, and the mountains of western Nevada (see insert, at left), there are now estimated to be fewer than 50 Sierra Nevada red foxes left in existence. Interestingly, human hunting and trapping practices are believed to have had little influence on the species' decline.
"Trapping and hunting likely had a negligible effect upon the Sierra Nevada red fox due to the low numbers taken each year," report Perrine and his colleagues. "[Previous assessments conducted in 1937] estimated the total harvest to be about 21 individuals annually, and they did not consider this to be a threat to the population." Perrine continues:
From 1940 through 1959, only 135 red fox pelts were taken throughout California, with exotic red foxes from the lowland population comprising an increasing portion of the statewide harvest after 1950 (Gould 1980). After 1959, the average annual harvest from the mountains was only two foxes (Gray 1975). Despite the low harvest levels, state resource managers were concerned about any preventable sources of mortality upon a species thought to be in decline. In response to this concern, the California Legislature prohibited trapping and other non-scientific take of red fox throughout the state in 1974 (Gould 1980). The moratorium remains in effect today.
So how was the Sierra Nevada red fox undone, if not through hunting and trapping? Perrine and his colleagues note that sources of red fox mortality not directly associated with humans are poorly known," but suspect some of the blame may rest with harmful ranching practices:
Like many other predators in the Sierra Nevada, red fox populations probably suffered from predator-eradication programs associated with livestock production (Grinnell and others 1937). Sheep ranchers routinely placed poison in dead sheep, killing thousands of predators and scavengers. In addition, over-grazing of mountain meadows by livestock likely harmed Sierra Nevada red fox indirectly by reducing the forage available for prey species (Grinnell and others 1937). Eliminating the use of poisons and reducing sheep allotments at high elevations in the Sierra undoubtedly benefited Sierra Nevada red fox conservation, although the absolute effects can only be surmised.
Sightings in recent years have been limited primarily to two small, isolated populations in the Sierra Nevada mountains of California, "one in the vicinity of Lassen Peak at the most southerly extent of the Cascades range, and one in the vicinity of Sonora Pass, approximately 160 miles to the south in the Sierra Nevada range," according to a 2011 announcement released by the US Fish and Wildlife Service.
"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," stated Sarah Stock, Wildlife Biologist in Yosemite National Park, in a statement. "We're excited to work across our boundary to join efforts with other researchers that will ultimately give these foxes the best chances for recovery."
The National Park Service adds:
The Yosemite carnivore crew will continue to survey for Sierra Nevada red fox using remote cameras in hopes of detecting additional individuals. At each camera station, the crew also set up hair snare stations in the hopes of obtaining hair samples for genetic analysis. Through genetic analysis, the park can learn more about the diversity within the population and to confirm whether the fox(es) detected in Yosemite is genetically related to individuals from the Sonora Pass area.
These Sierra Nevada red fox detections are part of a larger study funded by the Yosemite Conservancy to determine occurrence and distribution of rare carnivores in Yosemite National Park. Thank you to all our colleagues who have been helping us with this project in many important ways (UCD, USFS, CDFW, Central Sierra Environmental Resource Center, Bureau of Land Management, and Yosemite backcountry rangers and volunteers).