Chick Energy Balance in the Whitechinned Petrel, Procellaria aequinoctialis

Abstract

We investigated the energy delivery to, and energy expenditure of, Whitechinned Petrel (Procellaria aequinoctialis) chicks at Sub-Antarctic Marion Island. Meal mass and energy content of the food fed to chicks were variable. Feeding frequency was generally low and irregular. We calculated an energy budget based on measurements of energy expenditure and rates of mass accumulation. Energy received soon after hatching was in excess of maintenance requirements and was presumably laid down as an energy reserve. The chick experienced periods of relative fasting during growth when energy expenditure for maintenance and biosynthesis alone exceeded total energy delivery. Energy reserves sustained the chick during these periods, including that immediately prior to departure from the nest, allowing the adults to extend foraging periods when food was in short supply. Total energy ingested by a chick from 8 to 96 days of age was estimated to be ca. 67,000 kJ compared to an energy expenditure over the same period of ca. 54,000 kJ. Energy accumulated as chick biomass was estimated to reach an maximum of ca. 9,000 kJ.