Meeting Abstract
P2.21 Sunday, Jan. 5 15:30 Allostatic Load: Heart Rate and Corticosterone in Free-living Gambel’s White-crowned Sparrows (Zonotrichia leucophrys gambelii) WORD, KR*; WINGFIELD, JC; University of California, Davis krlizars@ucdavis.edu
Previous investigations have shown that heart rate is correlated with oxygen consumption in white-crowned sparrows, Zonotrichia leucophrys gambelii. Here, we apply that relationship to estimate and analyze total energy expenditure in free- living birds, using heart rate as a proxy for VO2. Regulation of energetic expenditure, considered here as allostatic load, is central to organism-environment interactions, and the value of responses that modify behavior or physiology is often measured in terms of energetic benefits. In addition to total energy expenditure, real-time measurement of heart rate offers the opportunity to examine daily activity patterns, night-time energetic expenditure, and responses to weather and other environmental stimuli. Furthermore, these investigations can address whether corticosterone secretion is directly related to these patterns. Although baseline corticosterone, proposed to mediate physiological responses to variation in allostatic load may not be correlated with corticosterone titers in captive animals under constant conditions, the relationship to individual variation in energetic profiles under natural conditions may be more meaningful.
