Heat loss in penguins during immersion and compression

Abstract o 1. The effectiveness of the feathers as insulation against heat loss during immersion and compression were studied. 2. Heart rate, body, skin, wing and foot temperatures and V̇ O 2 were measured under steady state conditions in air at 13°C, and when immersed in water at water temperatures of 5–25°C and 1 and 2 atmospheres absolute pressure. 3. Conductance of raw pelts was measured in air at 0°C, and in water at 5°C, and at pressures of 1 and 2 atm absolute. 4. V̇ O 2 was 1·6–3·5 times higher during immersion than when resting in air. 5. Total conductance averaged 2·9 times during immersion than when resting in air. 6. It is metabolically expensive for these small endotherms to go to sea.