The experts report that animals like the cactus mouse and the white-tailed antelope squirrel have experienced different exposures to climate warming compared to native birds, despite living in the same part of the Mojave Desert.
“Scientists tend to assume that most species in a region experience the same exposure to temperature or precipitation changes, and that they all respond in the same way. But we’re finding now that animals have diverse strategies for reducing their exposure to hot and dry conditions that could kill them,” said study senior author Professor Steven Beissinger.
“You should see these differences most strongly in a harsh environment like the desert, where life is really on the edge.”
Over the last 100 years, the Mojave Desert has become hotter and drier. During this time period, UC Berkeley scientists noted a collapse in native bird populations, which is likely due to the stress of higher temperatures. In 2018, the team reported that bird populations have declined rapidly, with 61 study sites losing an average of 43 percent of the species that were present a century ago.
In the new study, the same team has found that small mammal populations in the desert have remained relatively stable since the beginning of the 20th century.
“Mammals have shown this remarkable stability,” said Professor Beissinger. “It’s really quite interesting that, in the same region, with the same level of climate change, these two very similar taxa have responded very differently to the changes taking place.”
Based on computer model simulations, the researchers determined that small mammals are more resilient to climate change because they can escape the hot sun by diving into underground burrows. Birds need extra water to maintain a healthy body temperature, and are more active during the day compared to burrowing animals
“It’s becoming clear that animals across the planet are responding to climate change by shifting where they live and shifting when they breed, and we’re starting to get really strong evidence of population declines in certain areas that may be associated with warming,” said study lead author Professor Eric Riddell.
“Some estimates now suggest that one in six species will be threatened by climate change over the next century. Figuring out which species those are, what kind of traits they have, will be critical.”
“Desert species have been thought to be relatively invulnerable to climate warming, but many desert species are already at or near their temperature and aridity tolerance limits. Each species also has different degrees of resilience,” said study co-author Lori Hargrove, an ecologist at the San Diego Natural History Museum.
“Climate change may seem minor, only a few degrees, but it has already had, and is having, direct and significant impacts on many species, each of which, in turn, affects other species, with cascading effects yet to be realized.”
According to the study authors, modeling approaches that combine physiology and behavior are needed to more accurately predict a species’ persistence in the face of climate change.
“This study has made me realize just how complicated predicting the effects of climate change truly are,” said Professor Riddell. “It isn’t just about where the landscape is warming and where it isn’t warming. It’s a really complex process that involves many aspects of an organism’s biology, including their physiology, their behavior, their evolution — it’s all coupled. You need to take a really integrative approach to understand it.”
The study is published in the journal Science.