Field Metabolic Rates of Breeding Chinstrap Penguins (Pygoscelis antarctica) in the South Shetlands

Abstract

In a study using doubly labeled water, chinstrap penguins (mean body mass 3.79 kg) caring for chicks expired on average 2.06-2.44 mL CO₂g⁻¹ h⁻¹, depending on the equation used to calculate CO₂ production from isotope turnover (the two-compartment and one-compartment models for isotope dilution). This is equivalent to 4,720-5,597 kJ d⁻¹ and 4.0-4.7 times the estimated basal metabolic rate. Energy use while guarding small chicks on the nest was 0.58-0.69 mL CO₂ g⁻¹ h⁻¹ (1,768-2,124 kJ d⁻¹, or 1.5-1.8 times the basal metabolic rate), and it was 2.37-2.82 mL CO₂ g⁻¹ h⁻¹ (5,421-6,423 kJ d⁻¹, or 4.6-5.4 times the basal metabolic rate) when foraging at sea. The field metabolic rates measured at sea are similar to those reported for Adelie penguins but higher than those in studies of other penguin species. Adult penguins expired 2.27-3.13 mL CO₂ g⁻¹ h⁻¹ (5,033-6,995 kJ d⁻¹) while foraging for chicks in the guard stage and 2.45-2.60 mL CO₂ g⁻¹ h⁻¹ (5,693-6, 023 kJ d⁻¹) while foraging for chicks in the creche stage...