Meeting Abstract

P3.21  Wednesday, Jan. 6  Energetic expenditure in free-living red crossbills, Loxia curvirostra,using heart rate telemetry CORNELIUS, JM*; HAHN, TP; HUNT, KE; WIKELSKI, M; Max Planck Institute; University of CA-Davis; University of Portland; Max Planck Institute cornelius@ucdavis.edu

Estimation of metabolic rate in free-living, behaving songbirds has recently been made possible with the development of heart rate telemetry. By fixing radio-transmitters that have been modified to detect heart rate to free-living songbirds we can estimate the metabolic cost of different life cycle stages. Red crossbills, ( Loxia curvirostra), are opportunistic breeders and nomadic migrants that offer a unique opportunity to compare the metabolic costs of life cycle stages under very different environmental conditions (e.g., breeding in summer versus winter). As a first step in this long-term project, we measured heart rate in free-living red crossbills in Grand Teton National Park from July through September. This population did not breed due to a below average conifer seed crop, to which crossbills are specialized, but rather molted earlier than usual. We present heart rate data, foraging rates, habitat use and movement ecology of free-living male red crossbills from this below average food year and discuss these variables in the context of their unique opportunistic and nomadic annual schedules.