Postural changes and behavioural thermoregulation in Colobus polykomos: the effect of climate and diet

Summary Colobine monkeys are widely reported to spend considerable portions of their daily activity budgets resting. To test the hypothesis that resting and associated postures are related to energy conservation and thermoregulation, resting behaviours in Colobus polykomos are examined in relation to vegetation cover, weather conditions and diet. Seasonal differences in hunching are shown to be significantly correlated with cool, wet conditions and low energy intake, while postures associated with heat dissipation are more closely related to hot weather. These results support the hypothesis that C. polykomos are energy limited in wet seasons, and suggest their behaviourial thermoregulation is related not just to climatic conditions, but also to energy content and availability of food. Resume On a rapporte largement que les colobides passent une grande partie de leur temps a se reposer. Pour eprouver l'hypothese selon laquelle le repos et les attitudes qui s'y associent seraient lies a la conservation de l'energie et a la thermoregulation, on examine les comportements de repos chez Colobus polykomos en relation avec le couvert vegetal, les conditions atmospheriques et le regime alimentaire. On montre que les differences saisonnieres de la chasse sont significativement liees a des conditions fraiches et humides et a une faible absorption d'energie alors que les attitudes qui depensent de la chaleur sont plus etroitement liees au temps chaud. Ces resultats supportent l'hypothese que C. polykomos dispose d'une energie limitee en saison des pluies et suggerent que la thermoregulation active n'est pas liee uniquement aux conditions climatiques mais aussi au contenu energetique et a la disponibilite de la nourriture.