Enrichment Use and Welfare of Captive Orang-Utans

Abstract

Animal welfare in captivity is of increasing importance for ethical, as well as conservation and education reasons. The positive welfare of animals is dependent on their “freedom to adequately react and adapt to changes in the environment”. A crucial part of a zoo environment are visitors, who, as established in past research, can have a positive, negative, or neutral effect on animals and their behaviour. A negative visitor effect can lead to abnormal or self-directed behaviour such as regurgitation/reingestion and scratching, both commonly observed in captive primates. Therefore, visitors can have implications for welfare. A common strategy to reduce abnormal behaviours is the use of enrichment. This study investigates the visitor effect in a population of captive orang-utans, the reasons behind regurgitation/reingestion behaviour, and whether enrichment has an alleviating effect on stress. Through observations and measurements of visitors and noise, it was found that visitors increase scratching, therefore stress, and that the proportion of enrichment use is efficient in reducing scratching. No conclusion could be made about the origins of R/R behaviour. These results show that there is a negative effect of visitors on orang-utans at Apenheul, and that cognitively stimulating enrichment such as feeding puzzles, can potentially alleviate this. Thus, zoos need to address the issue of visitors through both education measures, enclosure modifications, and by providing proper species-specific enrichment.