Investigating the effects of sex and rearing-history on social network position in zoo-housed bonobos

Publication Type:
Conference Proceedings
Year of Publication:
Jonas Torfs, Jeroen Stevens, Jonas Verspeek, Daan Lameris, Marcel Eens, Nicky Staes
BIAZA Research Symposium, Date: 2021/07/13-2021/07/14, Location: Online
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Social network analysis can be a valuable tool for the management of zoo-housed animals and captive breeding programs, since an individual’s social network position is typically associated with its reproductive success, longevity, and overall welfare. This is especially true for primates, due to their rich and complex social lives. While many studies have investigated individual network position in primates, most studies typically sample only one group. Therefore, the question remains as to whether such results can be generalized across different groups of the same species. Moreover, many social network studies tend to focus on model species like macaques and chimpanzees, while other species, like bonobos, remain understudied. To fill these gaps in our knowledge, we constructed social grooming networks for 14 different groups of zoo-housed bonobos, and investigated the effects of sex and rearing-history (mother-reared versus atypically-reared, e.g. being wild-caught or hand-reared) on individual variation in social network position. Results showed that males and females did not differ in the amount of grooming given or grooming received, nor in network centrality. However, males were more restricted in their grooming relationships than females. In addition, an effect of rearing-history was found on the centrality of an individual, with mother-reared individuals being more central, and therefore more popular, in the grooming network than atypically-reared individuals. Rearing-history also affected the amount of grooming received, but in a sex-specific matter: mother-reared males received more grooming than atypically-reared males, while this effect was absent in female bonobos. While past studies on grooming behaviour in bonobos focused strongly on sex-differences, our results show that males and females do not differ in grooming rates, and both sexes can occupy central positions in the grooming network. However, males employ a different grooming strategy than females, since they tend to focus their grooming on a subset of group members, while females distribute their grooming more equally among group members. Our results also stress the importance of mother-rearing for the proper development of social skills. Especially in atypically-reared males, popularity in the grooming network appears to be impacted, which can be explained by the importance of maternal support and mother-son bonds in bonobos. Our study is one of the first to investigate individual variation in social network position in bonobos, and also one of the first social network studies to compile multiple groups into one large dataset, making the results more representative and reliable for bonobos as a species.


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