UC Santa Cruz

Energy budgets form an integral part of our understanding of animal energetics, particularly when presented in the context of reproduction. In this paper, I created a time-energy budget for a breeding pair of wandering albatrosses (Diomedea exulans) to estimate the annual breeding costs and food requirements of the population at Possession Island, Crozet Archipelago. For a breeding cycle that lasts 356 days on average, a pair uses 2,733 MJ to raise a single chick to fledging. This estimate is 1.21 times higher than previously calculated for wandering albatrosses breeding at Marion Island. Unlike the current analysis, the previous study assumed that foraging costs were constant across all stages of the breeding cycle. Recent evidence shows that foraging costs vary during breeding for wandering albatrosses at Crozet and this is probably true for all populations. Incubation costs have also been shown to be substantially lower than previously determined. Therefore, if a wandering albatross pair at Crozet uses a total of 2,733 MJ to breed, they would need to consume at least 1.7 kg bird(-1) day(-1) of fresh food, on average, to balance their own energy requirements and to provision a single chick for approximately 278 days. At this rate of food consumption, the breeding population at Crozet would consume approximately 340 tonnes of fresh food per breeding season.