COSTS AND BENEFITS OF MATERNAL AGGRESSION IN LACTATING FEMALE RHESUS MACAQUES

Data from over 400 hr of observation of mother-infant rhesus macaques indicate that during the first 12 weeks of lactation infants are at ri sk from other group members and that mothers use aggression as well as restraining to protect them, Maternal aggression was negatively corre lated with infant restraining. High-ranking mothers reacted aggressive ly to individuals handling their infants more than did middle- and low -ranking mothers. Conversely, middle- and low-ranking mothers restrain ed their infants more than did high-ranking mothers. Maternal aggressi on did not vary with infant age, Maternal aggression was directed towa rd a higher proportion of higher-ranking adult females and their immat ure offspring and was more likely to be followed by counter-aggression than nonmaternal aggression, i.e. aggression not related to interacti ons involving the infant. Middle-and low-ranking mothers suffered high er costs in terms of retaliation than high-ranking mothers. It is argu ed that the occurrence and distribution of maternal aggression among s pecies and individuals should depend on the risk posed to infants by c onspecifics as well as on the characteristics of the social structure (e.g. degree of asymmetry of agonistic contests) and of the mother (e. g. her dominance rank) which may affect the probability of retaliation .