As California Deserts Continue To Heat Up, Winners (Rodents) And Losers (Birds) Emerge
In the struggle to survive the ever hotter deserts of California, there are winners and losers. Among the losers are desert birds, whose populations have collapsed amid the heat stress of climate change. The winners, it turns out, are small burrowing mammals, including the the cactus mouse, kangaroo rat and white-tailed antelope squirrel, which take refuge from the sun underground. Researchers, including scientists from the San Diego Natural History Museum, published those results in the journal Science this month, noting that the stable mammal populations formed a hopeful contrast to the dire condition of birds.
“Why was the mammal community relatively stable compared to the bird community?” asked study co-author Lori Hargrove, an ecologist at the San Diego Natural History Museum. “Birds had a higher evaporative heat loss. Birds were more exposed to the effects of warming, so they had higher energy costs to maintain their body temperature, whereas mammals were able to buffer their body temperature by using burrows during the day.”
Temperatures have risen about 4 degrees Fahrenheit on average across the area studied, she said, but the heat affects birds and small mammals differently. As part of the study, scientists modeled each species’ body temperature and cooling needs under different desert conditions. To calculate that, they measured the conductivity of the animals’ fur or feathers, and used information on their heat reducing behaviors, such as evaporative cooling or denning underground.
The models showed that in the fight against climate change, there is not a level playing field for furred and feathered desert dwellers. Cooling costs - or the resources needed to maintain stable body temperature - were about 3.3 times higher for birds than they were for small mammals, the study reported. Rising temperatures resulting from climate change increased cooling costs by 58 percent for birds, but only 17 percent for mammals, it stated.
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https://www.sandiegouniontribune.com/news/environment/story/2021-02-17/desert-creatures-survive-climate-change-underground
