Spatial and social influences on the behaviour of captive chimpanzees

[摘要] Captive animals are frequently subject to imposed, uncontrollable stressors to which theyrespond through behavioural flexibility, or, failing which, exhibit pathology. Chimpanzeesprovide an intriguing model to examine how captive environments influence the responses ofanimals to stress. My study investigates the responses of a group of chimpanzees to imposedstressors of captivity at the Johannesburg Zoo, South Africa. My study comprised fourcomponents. Firstly, I examined the effects of spatial restriction on chimpanzee behaviourwith regard to an enclosure enlargement, testing several existing models of coping withspatial crowding and another model, based on the coping hypothesis of abnormal behaviour.Behavioural observations of the chimpanzees in their indoor and outdoor exhibits before,during, immediately after and 10 weeks after the enclosure reconstruction revealed that thechimpanzees used tension-reduction and conflict-avoidance tactics as a means to cope withspatial crowding. Moreover, abnormal behaviour appears to provide an outlet for stress undercrowding. Secondly, I assessed the long-term effects of past spatial environments on thespace use and group spacing of the chimpanzees, five years after the enclosure change.Through behavioural observations and mapping the locations of individuals, I found that thechimpanzees exhibit space-use bias and limited group spacing, contingent on the dimensionsof the old enclosure that were not explained by factors such as social or thermal conditionsand zoo visitor effects. I propose that the spacing patterns may be due to spatial learnedhelplessness. Thirdly, I examined the effect of two social manipulations, mandated by zoomanagement, on the behaviour and socio-dynamics of the chimpanzees. The chimpanzeesresponded to social change through selective social interactions and non-social behaviouralresponses suggest that removing an individual was less stressful than the merging of twogroups. Finally, I investigated the role of shade as a thermoregulatory resource for captivechimpanzees. Individuals used shade frequently despite observations taking place during theaustral winter period, suggesting that shade is a valuable thermal resource for chimpanzees.In conclusion, the chimpanzees responded to most imposed stressors (spatial crowding, socialchange and thermal stress) through behavioural flexibility, implying successful coping, butfailed to cope with previous spatial restrictions, resulting in limited space-use behaviour.

[发布机构] University of the Witwatersrand