The influence of brood size upon metabolic rate and body temperature in nestling Blue tits Parus caeruleus and House sparrows Passer domesticus

Authors


*Department of Zoology, Queen's University, Belfast, Northern Ireland.

Abstract

Metabolic rate and body temperature in nestling Blue tits and House sparrows were measured in broods of different size and age. Surface-volume ratio effects were found in both poikilothermic and homoiothermic Blue tits at ambients of 15°C but not at 20°C. The possibility of incipient hyperthermia amongst young nestlings maintaining sub-adult body temperatures is discussed. For the House sparrows heat retention by the nest was of greater importance than the surface-volume effect. Differences in nest structure between the two species are described and related to the thermal requirements of nestlings in large as against small broods.

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