Meeting Abstract
The White-tailed Antelope Squirrel (Ammospermophilus leucurus) is a diurnal rodent whose range extends from deserts of the Great Basin to Baja California, and thus must cope with high environmental temperatures during its day-to-day life. Increased temperatures and increases in extreme heat events from rapid climate change may importantly affect the behavior and physiology of these animals in the future. In order to understand the current performance of antelope ground squirrels and their overall flexibility we investigated the thermoregulatory capabilities of A. leucurus during summer and winter at multiple sites with differing elevations. We used flow-through respirometry to measure resting metabolic rate (RMR), evaporative water loss (EWL), and body temperature (Tb) in squirrels that were exposed to air temperatures (Ta) ranging from 15 – 52 °C. Measurements were taken at multiple sites at different elevations: Zzyzx (900ft asl), Joshua Tree (2500ft asl), Mid-hills (3000ft asl) and Mid-hills High (5000ft asl). Squirrels were very heat tolerant and able to evaporate large quantities of water when Ta exceeded Tb. While the breadth of the thermoneutral zone (TNZ) at Joshua Tree appears to have decreased from the Winter to the Summer, the breadth of the TNZ at Zzyzx appears to have broadened. During summer the mean RMR decreased with increasing altitude and was 5.9, 4.5, and 4.1 mW/g at Joshua Tree, Mid-hills, and Mid-hills High, respectively.
