STRAW AND FORAGE MATERIAL AMELIORATE ABNORMAL BEHAVIORS IN ADULT CHIMPANZEES

In an effort to reduce abnormal behaviors, especially regurgitation an d reingestion, and promote higher activate levels, straw and scattered forage material were added to the enclosures of 13 indoor-housed chim panzees (Pan troglodytes) living in pairs and trios. Behavioral effect s were examined by comparing 65 hr in the baseline condition with 65 h r in the experimental condition. Subjects spent 8.7% of observed time foraging or otherwise manipulating the straw, and no evidence of habit uation was found over 9 weeks. Males foraged at a rate three times tha t of females. Overall, abnormal behavior was significantly reduced. Ex amined alone, regurgitation and reingestion levels fell to less than o ne-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 term s of caretaker effort and expense and caused no health problems. (C) 1 997 Wiley-Liss, Inc.