Parental Care and the Development of Thermoregulation in Red Junglefowl

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Abstract
Few newly hatched birds are capable of maintaining a stable elevated body temperature at air temperatures encountered in the wild. The brooding behaviour of young red junglefowl (Gallus gallus spadiceus) and the changes in brooding that occur with the development of homeothermy were examined to determine the importance of thermal factors in parent-young contact. A fall in cooling rate and a rise in body temperature occur in junglefowl chicks in the days following hatching, and the young spend less time in contact with the hen as these changes occur. The length of brooding bouts is jointly determined by air temperature and the age of the young. Additional brooding at low air temperatures did not affect feeding by the parent or young. The general features of chick brooding persist when the hen is replaced with a model with brood patches at a temperature normal for maternal junglefowl. Brooding and huddling with other young are alternative thermoregulatory strategies. Behavioural thermoregulation by the young accounted for most features of contact between parent and young. Termination of brooding by the parent and reduction of chick heat loss by changes in parental posture may also influence brooding. Reliance on behavioural thermoregulation may permit development in a wide range of thermal environments.