65.10 Jan. 7 Calibration of heart rate and energy expenditure during flight and at rest in a passerine BOWLIN, M.S.*; WIKELSKI, M.C.; Princeton University; Princeton University email@example.com
Previous calibrations between heart rate and energy expenditure measured using either doubly labeled water or respirometry have shown that in large birds, for a given species and activity there is generally a linear relationship between the two variables—i.e. the oxygen pulse remains steady. Nothing is known about how closely heart rate tracks energy expenditure in small birds (e.g. passerines), however, so we performed two calibrations for Swainson’s Thrushes (Catharus ustulatus), a small (~35g) passerine migrant: one on resting birds and one on birds ‘migrating’ in a wind tunnel. Resting birds (three male, three female) were tagged with heart rate transmitters and placed in a respirometry chamber overnight, where both heart rate and VO2 were monitored. Energy expenditure was varied intraspecifically by varying temperature. For the flying calibration, heart rate was measured during five six-hour flights in a wind tunnel; the doubly-labeled water method was used to calculate average energy expenditure during each of the flights as well. Here we present the results of the two calibrations between heart rate and energy expenditure for Swainson’s Thrushes at rest and in flight.