Effects of browse, human visitors and noise on the behaviour of capive orang utans (2002)

Birke, L.

Abstract

Provision of fresh browse [usually willow] led to a decrease in the time spent inactive ..... it also led to an increase in the time spent by adults foraging for small food items in the woodchip floor-covering beneath the branches of browse. .. Adults used available paper sacks to cover their heads more during periods of high visitor density, and infants held onto adult more. .... Zoo managers may need to take visitor behaviour into account in order to promote orang utan welfare [p. 189].