Meeting Abstract
The model of allostatic load describes a functional role for the stress response in moderating energetic optimization and tradeoffs in a capricious environment. As such, it predicts a direct relationship between energetic costs incurred by environmental fluctuations and the endocrine mediators of allostatic processes, particularly glucocorticoids. Heart rate telemetry was used to examine effects of environmental conditions on energy budgeting in outdoor-captive and free-living Gambel’s white-crowned sparrows (Zonotrichia leucophrys gambelii). Baseline corticosterone was measured at the beginning (both groups) and end (captive only) of each trial. Weather, and particularly environmental temperature, influenced heart rate in both groups. In captive birds, heart rate was significantly predicted by an interaction between ambient temperature and subsequent baseline corticosterone levels. Implications of these subtle interactions for the allostatic load framework and the evolution of stress physiology will be discussed.
