The Development of Stereotyped Body Rocking in Chimpanzees (Pan Troglodytes) Reared in a Variety of Nursery Settings
This study measured the amount of time 7 chimpanzee infants devoted to stereotyped body rocking in a variety of nursery settings. Nine females and eight males ranging in age from three weeks to four years were included in the study. Some infants were placed in a peer group at a very
early age and were given minimal human contact, while others were provided with more frequent human interaction and were placed in peer groups at varying ages. During the course of the study, infants were housed with varying numbers of chimpanzee companions and some were also provided with
a canine companion. Four hundred and thirty-three hours of data were collected. Infants showed a decline in rocking over age and rocked less in the presence of a canine companion. Infant gender, the amount of human contact received at an early age, the age placed with at least one peer companion,
and the current number of chimpanzee companions did not affect the time devoted to body rocking. These findings demonstrate that animal managers should look beyond conspecific stimulation for improving the social environment and overall welfare of chimpanzees. These results are further discussed
in a framework of identifying possible strategies for minimizing rocking and promoting future behavioural competence in nursery-reared infants.