Abstract
Tall climbing frames were introduced into an outdoor compound for captive chimpanzees as a way of environmental enrichment. Behavioral changes were assessed in terms of the utilization of three dimensional space. Prior to the present study, a group of eleven chimpanzees had been kept in an approximately 700m2 semi-natural compound enriched with an 8m tall climbing structure, planted trees, and a stream. Chimpanzees in the wild spend more than half of the day in trees, preferring to stay high above the ground. In July 1998, we introduced a new enrichment device into the compound: tall climbing frames 15m in height. The climbing frames consisted of three high towers equipped with platforms and ropes to climb up and down and to traverse between the towers, as well as being connected to the existing set of frames. We videorecorded the chimpanzees' behavior in the new environment during the daytime from 9:30am to 4:30pm continuously. Chimpanzees spent 81% of the observation time on the climbing structure, during 39% of which they occupied locations more than 8m above ground, in the space newly made available. All chimpanzees used the climbing structure throughout the day with little individual difference. The change in activity budget clearly showed that the 15m high climbing frames proved instrumental in facilitating three dimensional space utilization promoting the psychological well-being of captive chimpanzees.
