The squirrels gliding amid the mountains east of Los Angeles have been, for the most part, flying under the scientific radar. There has never been a single scientific paper published specifically about the San Bernardino flying squirrel (Glaucomys sabrinus californicus), even though hundreds of papers about squirrels in general are published every year.
Despite this scientific oversight, the San Bernardino flying squirrel—a subspecies of the northern flying squirrel—has become very popular among some conservationists, who have been fighting to get it protected under the Endangered Species Act (ESA) since at least 1985. This week they finally made progress: the U.S. Fish and Wildlife Service (FWS), in response to a 2010 petition from the Center for Biological Diversity (CBD), agreed that the squirrels may deserve ESA protection. The agency said it will make a recommendation, either for or against protection for the subspecies, by April 2016.
Of course protecting a rare species depends on possessing detailed scientific information about its ecology, habitat use, threats and behaviors. We don't have much of that for the San Bernardino squirrel. Here's what we do know: They are medium-sized gray-brown squirrels which, like others in their family, possess wing-like skin flaps between their legs, which allows them to jump and glide up to 90 meters from tree to tree. They live in high-elevation forests exclusively on the San Bernardino Mountains. They used to be found on the San Jacinto Mountains as well, but the squirrels haven't been seen there since at least 1980. Their remaining habitat is completely isolated by the Mojave Desert and several deep passes, so they can't expand their range. The most recent estimate of their population put it at less than one squirrel per hectare, but that was from a trapping survey of the entire region conducted way back in 1998.
FWS started looking into the status of the squirrel in 2012 when, prompted by the CBD petition, they opened a public-comment period on the animals. That should have been followed within months by a decision to propose an endangered listing or not—but that next step never happened. CBD threatened to sue. The agreement this week was part of a settlement with CBD under which FWS promised to move forward on the squirrel and nine other species that have been stuck in a backlog of ESA decisions.
According to CBD's petition, the squirrels face multiple threats. The San Bernardino Mountains are warming and drying due to climate change and drought, making the lower elevations too dry for truffles (the squirrels' favorite food). Meanwhile, forest management practices the CBD calls "misguided" have removed too many of the high forest canopy limbs the squirrels use to traverse the mountains. More people are moving into the area, which could result in more habitat loss. To top it all off, those people are bringing more domestic animals such as cats, which are apparently preying upon the squirrels.
The next 18 months could make or break the fate of the rare squirrels. We can hope that FWS biologists and others will be able to dig up enough information to protect the subspecies. Maybe someone will even get a scientific paper out of the process.
Photo by Darleen Ortlieb Frechen, courtesy of the Center for Biological Diversity