Behavioral syndromes are associated with social plasticity and competence in a wild primate

The ability to optimize social behavior to varying socioecological circumstances has been termed “social competence” and relies on behavioral plasticity. Behavioral syndromes, i.e. consistent individual differences in intraindividual correlations among behavioral traits, appear to be a constraint on social competence, yet studies exploring this have largely been limited to experimental laboratory settings. Here, we tested the importance of behavioral syndromes to social competence in wild Barbary macaques ( Macaca sylvanus ), an endangered primate with established links between positive social relationships and survival. We studied two groups (n = 27 individuals) in which behavioral syndrome phenotypes were established in a previous study. “Shyer” (i.e., risk avoidant) individuals showed greater plasticity compared to “bolder” individuals in affiliative responses to the immediate social environment, being more likely to initiate grooming with larger numbers of conspecific bystanders present. Shyer individuals also increased their grooming social network connectivity to a greater degree than bold individuals in periods of higher anthropogenic pressure. In periods of colder weather, “shyer” individuals tended to concentrate their grooming network into fewer ties, whereas “bolder individuals” slightly increased their number of connections. In general, “shyer” individuals were more central in the grooming networks and any changes in network connectivity in relation to socioecology were small, reflecting the fact that stability in social network position is a common phenomenon in various taxa. Overall, we show that behavioral syndrome phenotypes influence plasticity in affiliative behavior and thus may be a key factor in individual responses to the rapidly changing socioecologies of the Anthropocene.