Walsberg 9725211 Despite the extraordinary challenges presented by high temperatures and the absence of water, a large number of animals survive without drinking while occupying extreme desert conditions. The goal of this study is to elucidate how the physiology of one important group of such animals allows them to survive desert conditions. Developing this understanding requires addressing three basic questions. (1) What themmal and hydric environments do these animals occupy in nature? (2) How do these animals thermoregulate under such conditions? (3) How do they meet their water requirements? This study will focus upon kangaroo rats, which are small rodents that are among the most conspicuously successful groups of desert mammals. The thermal and hydric conditions experienced by these small mammals in subtropical deserts will be quantified. Physiological analyses will focus upon determining how closely these animals approach their limits of tolerance to dehydration and high environmental temperatures under naturally prevailing conditions. This will include analyses of (a) short-term effects of high environmental temperatures upon body temperature, (b) intemmediate-term effects associated with animal dehydration during activity, and long-temm effects mediated through alterations in the location and timing of animal activity in nature.
