You can’t open your car door in the high desert town of Bodie, California, without hearing the piercing cries of its most prominent residents: thin-tailed, reddish-brown rodents known as Belding’s ground squirrels. They pop out from under the floors of shuttered bars and tear around meadows littered with rusting mine machinery. They stand attentively in the road, as if ready to collect entrance fees.
Bodie, once a gold mining town of 10,000, was turned into a state historical park in 1962. It’s a long detour off the main highway, through the sagebrush country east of the Sierra Nevada. Tourists amble through Bodie to gawk at the abandoned gold mill, sagging homes, and lonely hillside cemetery, but only a handful of park workers live there now. The weather is harsh, featuring wicked winds, freezing summer nights, and snowy winters with temperatures dropping as low as 20 below zero.
During the ice ages, some experts believe that species survived on mountaintops for thousands of years, out of reach of the glaciers that blanketed the land.
Yet Bodie has become an unlikely haven for the squirrels. Even as man-made climate change threatens their natural habitat, they’re flourishing among the town’s man-made ruins. With its decaying wooden buildings and junk-strewn meadows, the town has become a kind of Noah’s ark for animals, saving them from the worst ravages of global warming. At least for a while.
Recently, a team of scientists from the University of California-Berkeley, and the Missouri Botanical Garden resurveyed 74 sites in California where researchers had found Belding’s ground squirrels between 1902 and 1966. The team discovered that warmer, wetter conditions have forced the squirrels to leave 31 of those sites, especially ones in lower elevations. But they are surprisingly abundant in man-made locations at those same elevations—in campgrounds, alfalfa fields, and parks, including Bodie. There are three times as many squirrels in man-made locations as in the high-elevation Sierran meadows where they still survive in nature. (Bodie is, in fact, quite the magnet for wildlife. It’s also home to pronghorn antelope, coyotes, mule deer, badgers, jackrabbits, and bats.)
Toni Lyn Morelli, a former post-doctoral researcher at U.C. Berkeley who led the survey, is not sure why the squirrels are thriving in man-made spots. Do they like the irrigated turf grass? Drainage ditches? Food from tourists? Are Bodie’s crowds—as many as 200,000 visitors yearly—scaring predators away? It could be all, or none, of these. Whatever the reason, Morelli says, it’s clear that campgrounds, farms, and parks are providing buffers—what scientists call refugia—for a species in dramatic decline.
“There’s a possibility of extinction out of California for the Belding’s ground squirrel, based on climate data,” says Morelli, who now works at the Northeast Climate Science Center. “Our study shows that refugia in general seem to exist, and they have a significant impact on population sustainability and persistence. It’s exciting to have something positive come from human presence.”
The concept of refugia—isolated pockets of favorable conditions in otherwise inhospitable regions—is not new. During the ice ages, some experts believe that species survived on mountaintops for thousands of years, out of reach of the glaciers that blanketed the land. In the 21st century, species are threatened by heat, not ice. The Sierra Nevada’s glaciers have shrunk by an average of 55 percent since 1903. Rather than cling to mountaintops, some species may respond to the warming trend by moving down into icebox canyons and refrigerator valleys where cold air settles at night. That might be another reason Bodie is so attractive to the Belding’s squirrels, but park scientists don’t yet know if the valley it sits in qualifies as a “cold air sink.”
Kelly Redmond, deputy director of the Western Regional Climate Center in Reno, Nevada, considers identifying those cold spots a top priority. There are potentially millions of hollows in the West that could function as climate refugia, he says, ranging from fog-shrouded tracts of the Sacramento Valley to rock piles the size of buildings.
But of course, no one knows how long the cold spots will stay cold. And since no one really knows what makes man-made places like Bodie work as refugia, it’s not clear how long they’ll last, either. It takes only one late snowstorm, coming after hibernation, to wipe out a population. But for now at least, Bodie is a hedge against extinction, an emergency shelter for the squirrels.
A Ghost Town’s Second Life as a Climate Refuge for Rodents was first posted on November 19, 2013 at 6:00 am.
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