Meeting Abstract

P2.117  Thursday, Jan. 5  Changes in Body composition and the metabolic response to high and low evaporative water loss during short duration flights in the American Robin (Turdus migratorius) GERSON, A.R.*; GUGLIELMO, C.G.; Advanced Facility for Avian Research, Dept. of Biology, University of Western Ontario; Advanced Facility for Avian Research, Dept. of Biology, University of Western Ontario agerson2@uwo.ca

During avian flight both lipids and protein are catabolized, resulting in significant reductions in fat stores, muscle mass, and organ sizes over the course of an endurance flight. We have recently shown that the rate of protein catabolism in flight is an adaptive metabolic strategy to provision water. In an attempt to more fully understand the effect of water loss on the metabolic response during the early stages of flight, American robins were flown in a climatic wind tunnel under high and low humidity conditions for up to 1.5 h. Body composition was measured using quantitative magnetic resonance body composition analysis before and after flights, and blood was taken before and immediately after flight to measure plasma metabolite levels. Flight duration ranged from 17 - 92 minutes. There were significant reductions in mass, lean mass, and fat mass with flight duration, but there were no significant differences between humidity regimes on this short time scale. Plasma ß-Hydroxybutyrate and non-esterified fatty acids increased and glucose decreased during flight, irrespective of flight duration or humidity regime. Plasma triglycerides, glycerol, and phospholipids were not different from rest. Our findings agree with previous studies of the metabolic response to flight, and despite dramatic effects of ambient conditions on rates of lean mass catabolism during long duration flights, plasma metabolites of birds flown for short duration remained unaffected by ambient conditions experienced during flight.