By Debra Varnados

San Diego Natural History Museum Flying Squirrel Outreach Coordinator Brian Gibson and his wife, Wendy Wilson-Gibson, look over vegetation measurements at the Idyllwild Nature Center Flying Squirrel Feeding Station last Friday.
Photo by Debra Varnados


Preliminary results of a three-year study funded by the U.S. Fish and Wildlife Service, and conducted by scientists at San Diego’s Natural History Museum, show no evidence of the Southern California Flying Squirrel in the San Jacinto Mountains, leading to continued conjecture about the cause of their apparent disappearance and possible future research into their habits and behavior.

So far, native mice and rats, a spotted skunk and a gray fox have been documented at feeding stations in or around Round Valley, above the Palm Springs Tramway; at the Idyllwild Nature Center; the James Reserve behind Lake Fulmor; and in the backyards of local citizen scientists, project volunteers who are curious about science, and love and feed animals.

Researchers had hoped to capture images of the nocturnal flying squirrel using the 16 infrared motion-sensitive cameras installed two months ago.

“We’ve looked for them in the San Jacinto Mountains since the late Zoologist Joseph Grinnell first heard them chattering along Idyllwild’s Strawberry Creek in 1908,” Brian Gibson, SDNHM outreach coordinator, said. “But we haven’t found any.”

Gibson and his wife, Wendy Wilson-Gibson, a writer and curator, were in Idyllwild Friday to measure the vegetation around the feeding stations, including the diameter, height and distance of the trees from feeding stations, and the depth of the litter and duff on the ground, where flying squirrels dig for truffles and lichen.

Terry and Diane Blansfield’s birdfeeder in Crestline, San Bernardino County. This flying squirrel was captured on their citizen scientists’ cam.
Photo courtesy the Blansfields

Local habitats will be compared to San Bernardino Mountain habitats where flying squirrels are known to nest in power poles and trees with holes, many times carved out by acorn woodpeckers, and in the case of trees, by broken limbs. At least 30 people who feed wildlife and birds in those mountains and who have cameras mounted in their backyards have seen them.

“Seven is the most we’ve gotten on camera there. They were glommed onto a normal-size birdfeeder, pulling at sunflower seeds, swaying in the wind, and not fighting … I think it must have been a family group.”

Palmer’s “Fieldbook of Mammals” describes flying squirrels as “small, lively, elusive, mischievous and of dazzling beauty.” Using a membrane going from their wrists and attached to their ankles, “they can glide more than 160 feet from a 60-feet perch, or cover 75 feet in 12 seconds over the ground.”

SDNHM’s search for this mystifying creature in the San Jacintos began in September and is the first time the museum has recorded data with the help of citizen scientists in a place where no one has recently seen a flying squirrel.

“We’ll be asking if there is something different in the two habitats. Why are there so many squirrels over there? Why aren’t the squirrels here?” Gibson said.

Explaining the apparent disappearance of the flat-tailed, brown, furry mammals, Gibson said, “We don’t know why they’re seen there, but what we think might be happening is, as the climate warms over time, conifers such as pines — which need cooler temperatures — retreat to the peaks. We call this the ‘Sky Island Effect.’”

“Squirrels need conifers. San Bernardino is higher and they have more of these kinds of conifers. While we found flying squirrels there that live primarily in oak forests, we also notice there are not as many pines here, so squirrels may not have enough pine nuts to eat.”

Predation could be a factor. Flying squirrels, “which are smaller on average than gray and ground squirrels, are engineered for cold weather and night vision — they’re preyed upon by nocturnal animals like owls.”

But “the landscape and the ecosystem in the area are changing over time,” Gibson said. “As the mountainsides get drier and drier, and fires come through, it is less likely for a conifer to grow back and more likely for manzanita and other shrubs to grow in areas like the winter slope of the San Jacinto,” Gibson said.

Wilson said “there seem to be more dogwood trees in the San Bernardino Mountains, too.

“Flying squirrels like to eat their berries,” Gibson added.

Steve Olson, an Idyllwild citizen scientist, lives on Strawberry Creek. At one time, four cameras were mounted on his properties, one a gift from his children.

“I’ve seen flying squirrels only in pictures, not a live one. Being a part of the survey has been fun. My wife, Stephanie Yost, says that I’m the oldest kid in the family. Seeing a flying squirrel would be outstanding.

“We understand they are attracted to water, so we would have the right environment. I think [lack of sightings] may have to do with the time of year. With the change of seasons and the weather, from winter to spring, we could get more results.

“But the primary reason we don’t see them would be human encroachment on their habitat,” which is seen daily in the gray squirrel death toll from vehicle traffic on Highway 243.

“We’ve taken over more of their habitat. There are more of us than them,” Olson said. “But I think they are still here.”

Flying squirrels fascinate kids and adults, figuring in the imagination of scientific and popular culture and folklore. They have symbolic significance. Legends are told about them.

“SDNHM researchers would have been really surprised if we did find them,” Gibson said. “It would have been really big news.”

“They’re cool … fun … super-social and charismatic. They may be here, but we don’t know, because we haven’t seen them. The last undocumented sighting in the San Jacinto Mountains was in the 1990s.”

Friday, at the Nature Center, Gibson and Wilson-Gibson gathered data on Incense cedars, Jeffrey and Coulter pines, and oaks, for use by the project’s sponsors: SDNHM; U.S. Fish and Wildlife Service; U.S. Forest Service; Big Bear Alpine Zoo; San Jacinto Mountain State Park Wilderness; Palm Springs Aerial Tramway; and the James Reserve.

“On the whole, the project will focus on trying to find more funding and going back to the San Bernardino Mountains, and possibly doing distribution studies to pinpoint a family group of squirrels, and putting GPS on them to track where they go,” Gibson said. “SDNHM scientists hope to prepare a paper on the project’s finding and implications.”

For information on the project, visit


  1. Regarding your Flying Squirrels search in the San Jacinto Mountains in Idyllwild. Would it be possible to relocate some of the Flying Squirrels from Big Bear to the San Jacintos?
    This would help establish a New Colony in Idyllwild and better assure they won’t be wiped out by a single massive forest fire incident.
    Please feel free to publish or distribute my inquiry.
    Bear and Mona williams,
    Fern Valley, Idyllwild.