Food and Energy Requirements of Adélie Penguins (Pygoscelis adeliae) on the Antarctic Peninsula

Abstract

Adélie penguins (mean body mass 3.81 kg) brooding small chicks had field metabolic rates (FMRs, measured using doubly labeled water) averaging 1.64 mL CO₂, g⁻¹ h⁻¹, equivalent to 3,896 kJ d⁻¹ and 3.8 times basal metabolic rate (BMR). Energy utilization while on the nest was 2.0 X BMR, and it was 5.4 X BMR when off the nest, including time spent foraging at sea. These FMRs are higher than in other species of penguins and may reflect an intense foraging effort associated with a relative scarcity of food during our study. The penguins ate only krill (Euphausia superba), primarily juveniles of intermediate size, which contain much water, little lipid, and relatively lowu metabolizable energy content compared to gravid female krill. Low water intake rates indicated that the penguins did not drink much fresh water or seawater and that they did not consume quite enough food to pay their own energy expenses after feeding their chicks. Their utilization of body fat to pay the difference should have amounted to about 33 g d⁻¹ during this phase of the breeding cycle. We estimated that the 25,500 Adélie penguins using the Arthur Harbor area around Palmer Station would consume about 27.5 metric tons of krill each day. Six hundred twelve penguins (total biomass of 2,330 kg) would consume about the same amount of krill per day as does one Antarctic fin whale weighing 48,000 kg.