Comparison of Methods for Evaluating Energy Expenditure of Incubating Wandering Albatrosses
Résumé
Measurements of incubation energetics can vary depending on the method used to measure metabolism of an incubating bird. Therefore, we evaluated the energy expenditure of six male and four female wandering albatrosses (Diomedea exulans Linnaeus) using doubly labeled water (DLW), the rate of mass loss, and estimates of metabolic water production derived from water influx rate (WIR). Incubation metabolic rates (IMR) determined with DLW ( kJ kg1 d1 SD) were 16921 significantly lower than estimates derived from mass loss (27746 kJ kg1 d1 SD) and WIR (malesp28960 kJ kg1 d1 vs. femalesp40069 kJ kg1 d1 SD). Estimates of IMR from mass loss and WIR were similar to IMR (30539 kJ kg1 d1 SD) determined by respirometry in a previous study, and IMR from DLW was similar to estimates based on heart rate (HR; 14726 kJ kg1 d1 SD) determined in another study. Applying the different measurements of IMR to construct an energy budget, we estimate that a breeding pair of wandering albatrosses spends 124–234 MJ to incubate the egg for 78 d. Finally, IMRs determined with DLW and HR were similar to estimated basal metabolic rates derived from six different allometric equations, suggesting that heat production from adult maintenance metabolism is sufficient to incubate the egg.