A note on the influence of visitors on the behaviour and welfare of zoo-housed gorillas

Visitors to zoos can be a source of potential stress to some captive-housed primates. To date, the effect of the human audience on the welfare of captive gorillas has been overlooked. This study thus examined the behaviour of six zoo-housed gorillas during periods of both high and low visitor density, to establish whether there was any effect of audience numbers on the animals' well-being. Low visitor density encouraged behaviour suggestive of relaxation, with gorillas spending a significantly greater proportion of time resting. High visitor density, by contrast, encouraged significantly more intragroup aggression, stereotypies and autogrooming. The findings suggest that gorillas, like many other species of primate, are excited by high numbers of visitors.