Socio-sexual behaviour in two groups of captive Bonobos (Pan paniscus): a description and functional analysis

Abstract

This study is an investigation into bonobo socio-sexual behaviour in two captive groups, Twycross in Leicestershire and Planckendael in Belgium. There are four main areas of emphasis and these are reconciliation, tension reduction, social bonding and social status affirmation, which formed the four hypotheses. Both study groups had a similar range, frequency and distribution of socio-sexual behaviour across the sexes and ages. Differences were apparent both within each group and between them and also comparing data from other captive and wild studies. Socio- sexual behaviour occurs in many species, but it is the range of socio-sexual behaviour, frequency, and combinations of age and sex that are specific to bonobos. Quantitative data on socio-sexual behaviour were collected using all occurrences and scan sampling techniques, to test the hypotheses using SPSS for windows. The four hypotheses tested are as follows: Hypothesis I: Reconciliation is in the form of socio-sexual behaviours. Hypothesis II: Socio-sexual behaviours are a form of tension reduction. Hypothesis III: Socio-sexual behaviours are an expression of social status. Hypothesis IV: Social bonding is increased by the occurrence of frequent genital contacts. Results indicate that of the four hypotheses tested, two were relatively strongly supported by the data; these were tension reduction and social status affirmation. Of these, the evidence for tension reduction was the strongest. The hypothesis for reconciliation was not supported by the data, but the social bonding hypothesis was partially supported. Socio-sexual behaviour was particularly evident during feeding and agonistic interactions (although agonism frequency was low). Rank related sexual