EVALUATION OF INTRODUCTION PROCEDURES IN CAPTIVE CHIMPANZEES

Chimpanzee introductions can be stressful and even dangerous for the i ndividuals involved, and different facilities use different approaches to group formation. However, little empirical evidence has been avail able to evaluate the different factors related to successful or unsucc essful chimpanzee introductions. This study evaluated a variety of fac tors, such as age, sex, previous experience, and the behavior displaye d during the initial introduction period, to determine any influence o n the outcome of the introduction in 165 dyadic introduction events. T he direct introduction of one chimpanzee to a group or to another indi vidual resulted in an overall success rate of 86.7%. The first few soc ial interactions were characterized by more aggressive and submissive behavior than affiliative behavior, but this trend was quickly reverse d. Unsuccessful outcomes were more common if wounding occurred, if eit her individual was male, and if the newcomer had high levels of submis sive behavior. Among male chimpanzees, the behaviors during the first 10 min of the introductions were characterized by more submissive beha vior of the newcomer and more aggressive behavior of the introduction partner. The frequency of aggression by the introduction partner was h igher when the newcomer was introduced to one chimpanzee at a time rat her than to the group as a whole. This information may have important consequences for how we view chimpanzee group formation, and factors s uch as previous experience and aggression may be less important than t he method of introduction and the level of submissive behavior. (C) 19 97 Wiley-Liss, Inc.