Allostatic Load in Gambel’s White Crowned Sparrow, Zonotrichia leucophrys gambelii: Relationships With Glucocorticoids

Regulation of energetic expenditure in a changing environment, considered here as allostatic load, is central to organism-environment interactions. The value responses that modify behavior or physiology coping strategies often measured terms benefits. In this study, the total cost incurred by Gambel’s white-crowned sparrows, Zonotrichia leucophrys gambelii , was assessed using heart-rate transmitters. use heart rate validated proxy for metabolic via flow-through respirometry. Applying an indicator we confirmed ambient temperature under wintering conditions influences load. However, baseline corticosterone, proposed mediate physiological variation does not appear vary with captivity, field. relationship between load and plasma corticosterone levels also investigated manipulating feeding effort captive sparrows sand-excavation challenge approximated type foraging work these birds normally perform wild. This experiment designed test hypothesis experimentally increased induces elevation corticosteroids. We did find support hypothesis. suggest adrenocortical response may be limited overload environmental meaningfully threaten energy imbalance, indicating new targets further research.