| Abstract: | In an effort reduce abnormal behaviors, especially regurgitation and reingestion, and promote higher activate levels, straw and scattered forage material were added to the enclosures of 13 indoor-housed chimpanzees (Pan troglodytes) living in pairs and trios. Behavioral effects were examined by comparing 65 hr in the baseline condition with 65 hr in the experimental condition. Subjects spent 8.7% of observed time foraging or otherwise manipulating the straw, and no evidence of habituation was found over 9 weeks. Males foraged at a rate three times that of females. Overall, abnormal behavior was significantly reduced. Examined alone, regurgitation and reingestion levels fell to less than one-third their former level and ceased to rise with elapsed time since feeding. Subjects spent less time displaying and more time locomoting and playing. This enrichment option was found to be practical in terms of caretaker effort and expense and caused no health problems. Zoo Biol 16:225–236, 1997. © 1997 Wiley-Liss, Inc. |
