Spatial and social influences on the behaviour of captive chimpanzees
Date
2012-09-05
Authors
Duncan, Luke Mangaliso
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Abstract
Captive animals are frequently subject to imposed, uncontrollable stressors to which they
respond through behavioural flexibility, or, failing which, exhibit pathology. Chimpanzees
provide an intriguing model to examine how captive environments influence the responses of
animals to stress. My study investigates the responses of a group of chimpanzees to imposed
stressors of captivity at the Johannesburg Zoo, South Africa. My study comprised four
components. Firstly, I examined the effects of spatial restriction on chimpanzee behaviour
with regard to an enclosure enlargement, testing several existing models of coping with
spatial 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 the
chimpanzees used tension-reduction and conflict-avoidance tactics as a means to cope with
spatial crowding. Moreover, abnormal behaviour appears to provide an outlet for stress under
crowding. Secondly, I assessed the long-term effects of past spatial environments on the
space 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 the
chimpanzees exhibit space-use bias and limited group spacing, contingent on the dimensions
of the old enclosure that were not explained by factors such as social or thermal conditions
and zoo visitor effects. I propose that the spacing patterns may be due to spatial learned
helplessness. Thirdly, I examined the effect of two social manipulations, mandated by zoo
management, on the behaviour and socio-dynamics of the chimpanzees. The chimpanzees
responded to social change through selective social interactions and non-social behavioural
responses suggest that removing an individual was less stressful than the merging of two
groups. Finally, I investigated the role of shade as a thermoregulatory resource for captive
chimpanzees. Individuals used shade frequently despite observations taking place during the
austral winter period, suggesting that shade is a valuable thermal resource for chimpanzees.
In conclusion, the chimpanzees responded to most imposed stressors (spatial crowding, social
change and thermal stress) through behavioural flexibility, implying successful coping, but
failed to cope with previous spatial restrictions, resulting in limited space-use behaviour.