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First published online January 5, 2005
Journal of Experimental Biology 208, 317-325 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01397

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Energetics of a long-distance migrant shorebird (Philomachus pugnax) during cold exposure and running

Eric Vaillancourt¹, Sophie Prud'Homme¹, François Haman¹, Christopher G. Guglielmo² and Jean-Michel Weber^1,*

¹ Biology Department, University of Ottawa, Ottawa, Ontario, Canada
² Biological Sciences, University of Montana, Missoula, Montana, USA

^* Author for correspondence (e-mail: jmweber{at}science.uottawa.ca)

Accepted 15 November 2004

The metabolic consequences of cold exposure and exercise are not well characterized in birds. Ruff sandpipers Philomachus pugnax are migrant shorebirds traveling between Africa and Siberia for up to 30 000 km annually. Our goal was to quantify the fuel selection pattern of these remarkable athletes during shivering and terrestrial locomotion. We used indirect calorimetry and nitrogen excretion analysis to measure their rates of lipid, carbohydrate and protein oxidation at different temperatures (22, 15, 10 or 5°C) and different treadmill speeds (15, 20, 25, 30, 35 or 40 m min^–1). Results show that lipid oxidation supplies nearly all the energy necessary to support shivering and running, and that the pattern of oxidative fuel selection is independent of shivering or running intensity. During shivering, total ATP production is unequally shared between lipids (82%), carbohydrates (12%) and proteins (6%). During running, lipids remain the dominant substrate (66%), with carbohydrates (29%) and proteins (5%) playing more minor roles. The prevailing use of lipids during intense shivering and high-speed running is not consistent with the fuel selection pattern observed in exercising and cold-exposed mammals. The exact mechanisms allowing birds to use lipids at extremely high rates are still largely unexplored, and quantifying the relative importance of different fuels during long-distance flight remains a major challenge for future research.

Key words: oxidative fuel utilization, fuel selection, lipid, carbohydrate, animal energetics, indirect calorimetry, energy expenditure, shivering, exercise, ruff sandpiper, Philomachus pugnax

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