DYADIC INTERACTIONS OF INFANT LOWLAND GORILLAS IN AN OUTDOOR EXHIBIT COMPARED TO AN INDOOR HOLDING AREA

The behavior of two lowland gorilla mother-infant pairs living in a so cial group at Zoo Atlanta was compared in an indoor holding area vs. a n outdoor exhibit. Focal animal data were collected for each pair duri ng 30-min observation sessions over 24 days, alternating between indoo rs and outdoors. A variety of individual and social behaviors differed in the two conditions, particularly infant behaviors and infant-contr olled behaviors. Mothers and infants spent more time closer together i nside than outside, and infants left mothers more and mothers approach ed infants more outside than inside. Additional differences included m ore object examination and solitary play by the infants, and more feed ing by the mothers, outside. Mothers autogroomed more and infants enga ged in more self-manipulation inside. Additionally, there were signifi cantly more aggressive display behaviors directed toward the mother-in fant pairs inside than outside, and the adults engaged in coprophagy i nside but not outside. A variety of other behaviors measured did not c hange between the two environments. There was a clear effect on behavi or of the different housing conditions in which the gorillas were kept . (C) 1994 Wiley-Liss, Inc.