Long-term use of televisions, balls, and mirrors as enrichment for paired and singly caged chimpanzees

The evaluation of environmental enrichment techniques for nonhuman primates over long periods of time has had mixed results. Some studies report rapid habituation to new enrichment items, while others note continued use. We have investigated the use of three different enrichments that had been available to paired and singly caged chimpanzees for several years. Twenty subjects were observed during 200 hr of scan sampling while singly caged and while pair housed. Each subject had a variety of enrichments available and their use of a television, ball, and mirror were recorded. The chimpanzees had previous exposure to all of the items: televisions had been available for a mean of 22.75 months, balls had been available for 55.9 months, and mirrors had been available for 25.9 months. The results indicated that the chimpanzees continued to use the enrichments for small amounts of time (0.27%-1.53% of the observations) even after such prolonged exposure. Television and ball use were significantly higher than mirror use. Housing condition was not a significant factor in the analyses, contrary to expectations. We concluded that several simple enrichment items may be effective in offering variety and choices to the nonhuman primate and can be one element in a comprehensive environmental enhancement plan. © 1996 Wiley-Liss, Inc.