By Claire Daly
Small mammals may be better adapted than birds to the increasing temperatures of California’s deserts caused by climate change, according to a study by UC Berkeley researchers published Friday.
The study found that while small desert mammal species have largely maintained their numbers over the past century, the numbers of bird species have dropped as temperatures have risen. The only species of bird whose numbers have increased is the common raven, according to senior author and campus professor Steven Beissinger.
Beissinger explained that birds have to constantly deal with the heat of the deserts, whereas small mammals can shield themselves from the sun in underground burrows.
“You could have such radically different responses between the birds and mammals, two taxa that are pretty similar to each other in their life histories and their ecologies,” Beissinger said. “With this one exception, most mammals are able to use microhabitats that are cooler underground.”
The research centered around Death Valley and Joshua Tree National Parks, along with the Mojave National Preserve.
The Museum of Vertebrate Zoology and campus department of environmental science, policy and management collaborated on the study with the San Diego Natural History Museum, University of New Mexico and Iowa State University.
The study was conducted as part of the Grinnell Resurvey Project, through which campus scientists are repeating the research of Joseph Grinnell, founding Director of the Museum of Vertebrate Zoology, in order to determine how species population levels have changed.
According to James Patton, campus professor emeritus and study co-author, Grinnell left behind a rich legacy of archival data that the team was able to use to repeat his research.
Patton and his wife Carol Patton were the lead small mammal investigators for Death Valley National Park and parts of Mojave Preserve, despite being retired themselves.
“I prefer to spend my time out in the field and my wife has been going to various odd places and the ends of the earth with me over the decades,” Patton said.
Grinnell’s research offered a historical comparison for the study, and modeling based on climate change projections and animal specimen analysis also allowed the team to predict how species will be affected by future temperature increases.
According to Beissinger, the study demonstrates the harsh reality of climate change and shows exactly how species are and continue to be affected.
“Our study in this harsh environment shows that there’s direct effects on the physiology of the organism,” Beissinger said. “And those direct effects can be pretty severe.”