Abstract
Although negative visitor behaviours can cause distress or even death to zoo animals, research has shown that the mere presence of people at a zoo exhibit is associated with animal stress. The aim of this paper is to reiew existing research about these visitor effects. Research to date has shown that the presence, density, activity levels, size and proximity of visitors are all associated with behavioural changes in captive animals. However, almost all studies have investigated behavioural changes in primates and more emphasis is needed on studying a wider range of animal groups and stress indicators. There is also scope for integrating existing work with other ares of zoo audience research. Possible solutions to help zoos counteract visitor effects are offered.