ORANGUTAN BEHAVIOUR IN CAPTIVITY: ACTIVITY BUDGETS, ENCLOSURE USE & THE VISITOR EFFECT.

Abstract

Orangutans are great apes that are found in the forests of Borneo and Sumatra. In the wild, they live in complex rainforest habitats, and travel great distances daily for food. As a result of habitat destruction and poaching, these apes are now endangered. In captivity, orangutans become obese if not provided with sufficient arboreal stimulation. They are also known for their intelligence, and keeping them mentally occupied is a challenge. For captive orangutans, little is known about their activity budgets, enclosure use and how zoo visitors affect them. Hence, more knowledge is required to maintain the welfare of these intelligent apes.

In zoos, there is a current and ongoing interest for naturalistic exhibits, as such exhibits may provide greater stimulation for captive animals. Using features such as vegetation and rockwork, naturalistic enclosures are designed to increase species-specific behaviours by simulating wild habitats. Such exhibits have also been found to improve visitor appreciation of captive animals. In Singapore Zoo, the presence of two naturalistic orangutan exhibits provides the chance to study the behaviour of this ape in such enclosures. Hence, the activity budgets, enclosure use, and visitor effects on Singapore Zoo orangutans were investigated.

The results showed that captive orangutan activity budgets were age-specific, differed across enclosures, and were not dissimilar from that of wild orangutans. Exhibit use was influenced by both biological and environmental factors. Biological factors included age and dominance hierarchy in orangutans, and environmental factors included the availability and arrangement of structures within an exhibit, as well as features surrounding the exhibit. For visitor effects, large crowds, visitors with food, visitors who were looking or taking photographs, and visitors who were close by, all affected orangutan behaviour. On the whole however, the effects of visitors on orangutans in Singapore Zoo¿s enclosures were lesser than hypothesized. Interestingly, possible sources of visitor stress appeared to be alleviated by the large, naturalistic enclosure designs and the unusual husbandry routines implemented at Singapore Zoo. Being the first study on structure use in a naturalistic orangutan exhibit, and amongst the few existing studies on orangutan activity budgets and visitor effects, this research provides useful information for zoo management, and sets possible direction for future studies.