Your Help Needed to Find SoCal Flying Squirrels

San Bernardino flying squirrel | Photo: Darleen Ortlieb Frechen

The U.S. Forest Service is looking for your help as it studies one of Southern California's most endangered species. The San Bernardino flying squirrel, currently being considered for possible listing as an Endangered or Threatened species, is increasingly threatened by climate change, wildfire, and free-roaming cats. Biologists working with the San Bernardino National Forest want to gather all the information they can on the engaging little squirrels to get a better sense of just how they're doing in the wild.

And that's where you come in, if you live in or visit the San Bernardino or San Jacinto mountains. Many San Bernardino flying squirrel sightings are made by people who happen to spot the nocturnal rodents raiding their bird feeders at night, or who find them as roadkill. If you see a flying squirrel in the San Bernardinos or San Jacintos, U.S. Forest Service researcher Robin Eliason would like to know.

That holds especially true for the San Jacinto Mountains, where the diminutive gliders haven't been seen for decades; the squirrels are assumed to be either extinct or close to it in the San Jacintos. So if you do see one in Idyllwild, the biologists will really want to hear about it. Sad to say, that's pretty unlikely. Since the 1980s, the only sightings of the squirrels have come from the San Bernardino Mountains, and they're not faring all that well there either.


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A subspecies (Glaucomys sabrinus californicus) of the more widespread northern flying squirrel, San Bernardino flying squirrels inhabit forests of Jeffrey pine, white fir, and black oak, where they generally live off truffles -- the below-ground fruiting bodies of mycorrhizal fungi -- and lichens. (That is, unless they're raiding your bird feeder.)

Like their kin, San Bernardino flying squirrels don't actually fly, but rather glide from tree to tree by using kite-like skin that's connected to their fore- and hind-legs. They've been known to cover distances of 300 horizontal feet in a single glide.

As animals adapted to mixed conifer forests at the tops of mountains, San Bernardino flying squirrels are potentially vulnerable to climate change; if the mountains get too warm to support their preferred conifer species, the squirrels are out of luck. With climate change comes wildfire, and you might reasonably expect fires to threaten the squirrels. As it happens, Forest Service fuel reduction practices also take their toll by changing the forests' structure, removing snags and undergrowth, and altering the forest canopy to provide less fuel -- and less cover for squirrels. Drying, warming mountain forests also means fewer truffles for the squirrels to eat.

And of course, human presence is a problem, from the suburban or resort development that spans the length of the San Bernardinos, to the influx of outdoor cats that we humans bring with us.

In 2010, the Center for Biological Diversity petitioned the U.S. Fish and Wildlife Service to list the San Bernardino flying squirrel as either Endangered or Threatened under the U.S. Endangered Species Act. In 2012, USFWS agreed that listing might be warranted, which set in motion a 12-month deadline for the agency to make its decision. In April; 2014, with no decision forthcoming from USFWS, the Center for Biological Diversity notified the agency it intended to sue to force a decision. That resulted in a September 2014 settlement between the Center and USFWS in which the agency agreed to release a decision on the squirrel by the end of April 2016.

In the meantime, the Forest Service could really use your data on flying squirrel sightings, and if you have photos so much the better. Contact Robin Eliason at reliason@fs.fed.us or (909) 382-2832.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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