The discovery gives conservationists hope that the fox—listed as threatened by California—may just outfox extinction overall, scientists say.
The Sierra Nevada red fox subspecies hadn't been seen in central California since the 1990s and was considered gone from the area. Only one other population of Sierra Nevada foxes are known, farther north in the Lassen Peak region (see map).
But U.S. Forest Service officials suspected photographs taken by a trail camera near the Sierra Nevada mountains' Sonora Pass (see map) in August had captured a Sierra Nevada red fox gnawing on a "bait bag" of chicken scraps.
Researchers at the University of California, Davis, ran DNA tests on saliva samples from the bag, and sure enough, the spit confirmed the fox as a Sierra Nevada. Testing saliva is "not uncommon," said Ben Sacks, director of the Canid Diversity and Conservation Unit of the Veterinary Genetics Laboratory.
"We thought they were gone," Sacks added. "We were wrong."
Knowing there are two holdout populations of the subspecies "multiplies our reasons for optimism," Sacks added.
It "tells us not only are they not extinct, but now we're hedged," he said. "If something were to happen to one of those [populations], we have another to draw from."
Sly Fox Little Studied
Since 2006, Sacks has been studying red foxes in California—often joining the hunt for the Sierra Nevada fox. Even when he's hiking, "if I find fox-size feces at the right elevation, I pick it up and do the analysis," he said.
His genetic research, for instance, has revealed that many of the red foxes in the western U.S. are actually descendants of native Alaska and eastern U.S. foxes that were introduced in the 20th century.
But still, very little is known about the elusive Sierra Nevada subspecies—so little, in fact, that no one knows its exact population or why it's declining, Sacks said.
Sacks suspects the animals have escaped human detection in part because biologists' surveys are done at lower elevations—Sierra Nevada red foxes generally keep to the high mountains.
The new discovery "tells us we need to take them seriously," he said.
"We need some resources to study these guys and to find out how many are out there" and to "figure out how to protect them and ensure their persistence into the future."