Maternal aggression in lactating female Japanese macaques: Time course and interindividual variation

This study investigated the aggressive behavior of female Japanese macaques (Macaca fuscata (Blyth, 1875)) during lactation. Following parturition, the frequency of aggression showed an initial decline during weeks 1-2 of infant life, then increased to peak during weeks 7-8 post partum, and finally declined again to prepartum levels. Neither the initial decline nor the subsequent increase in aggression rate post partum was related to sociodemographic characteristics of the mother-infant dyad or to measures of maternal style. These results suggest that variation in postpartum aggression may be influenced less by the quality of the mother-infant relationship than by the mother's relationships the mother has with group mates.