Would you rather be a small desert-dwelling mammal, or a bird? In the Mojave Desert, an area that includes parts of California and Nevada, average temperatures have risen 3.6 degrees Fahrenheit and average precipitation has dropped by 10 to 20 percent over the past century. Over the same period of time, a team of researchers studying the area noticed a steep drop in bird populations. Interestingly, however, small mammals such as kangaroo rats and cactus mice weren’t showing the same declining trend. Trapping data showed that small mammal populations have remained fairly stable over the past century.
This disparity clued the researchers in to the idea that birds and small mammals coped with the rising temperatures differently. To better understand how both responded to heat, the scientists used computer models to simulate how much heat birds and mammals experience and to calculate how much heat they need to gain or lose to maintain a stable body temperature. The models took into account the shape of each species, how well their plumage or fur conducted heat, the various heat sources an animal might be exposed to, such as direct sunlight, or sunlight reflected from the ground, among other factors. The models showed that it was much harder for birds to cool off than for small mammals. Scientists say this is because small mammals burrow underground and are often active at night, whereas birds are more exposed to heat during the day.
It sounds more fun to fly than to burrow, but in a desert getting hotter and hotter, disappearing underground may be the best trick there is.