COMMUNICATION DURING INITIAL CONTACT - A COMPARISON OF SQUIRREL AND RHESUS MONKEYS

Initial collective aggression was exhibited in larger squirrel mon key groups; singly introduced males did not show aggression pre dominantly. In squirrel and rhesus monkey groups collective aggres sion was quantitatively and qualitatively similar. Rhesus also showed increased sexual behaviour (presentations by the females, and mounts by the males), whereas in the squirrel monkeys these sexual behaviour patterns were inhibited by collective aggression. (10 days after fusion began, presentation, mounts, and ‘specific aggression’ were observed frequently in squirrel monkeys). On the other hand during the phase of collective aggression some squirrel monkey males showed high frequencies of genital display and back rolling. Both behaviour patterns might express dominance, as did mounting in the rhesus. Genital display could be a ritual derived from sexual behaviour, as was put forward by PLOOG, BLITZ and PLOOG [1963]. Back rolling could be a ritualized body-care behaviour, serving to shorten inter individual distances. MAURUS and PLOOG [1968] observed that after brain stimulation aggressive and sexual behaviour could follow one another in quick succession. In this experiment the behaviour pattern of squirrel mon keys resembled the behaviour of aggressive rhesus monkeys. © 1969 S. Karger AG, Basel.