Maternal protectiveness is negatively associated with infant handling in wild Japanese macaques

Infant handling by a non-mother is common in many primate species. Despite the requirement of a triadic relationship among handler, mother, and infant, previous studies of infant handling have focused on characteristics of handler or interactions between mother and handler. In this study, we examined the influence of the mother-infant relationship (i.e., maternal style) on the frequency with which wild Japanese macaque (Macaca fuscata) infants were handled. We analysed behavioural data collected during 3 consecutive years and found that maternal style was characterised by three principal components: infant activity, rejection, and non-protectiveness. Infants who were less active and whose mothers were less protective received more frequent handling. These effects were particularly evident when handlers were thought to have less access to the infant. These complex interactions within the triadic relationship suggest that maternal style constrains the occurrence of infant handling in group-living primates.