Effect of human disturbance on body temperature and energy expenditure in penguins
A new method to measure and quantify human disturbance in seabirds is presented. The stomach temperatures of moulting emperor penguin chicks and adults (Aptenodytes forsteri) were recorded continuously using temperature loggers while the birds were exposed to various man-induced stimuli. Stimuli resulted in typical temperature rises that varied with the duration and strength of the stimulus. On average, the temperature rose by 1.5 K, the maximum reached being 2.6 K following a stimulus of more than 2 h duration. Minimal energy costs inducing the temperature rises could be estimated. Depending on the intensity of disturbance, minimal energy expenditure ranged between 3.2 kJ/kg and 9.7 kJ/kg, being slightly higher in chicks. This represented up to 10% of the daily energy demand during moult. The estimated minimal increase in metabolic rate during stress averaged 2.3 W/kg in chicks and 2.0 W/kg in adults (maxima of 4.2 W/kg and 3.3 W/kg, respectively).
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