Social rank and sex-biased maternal investment in captive Japanese macaques: Behavioural and reproductive data

This study investigated the relationship between social rank and sex-biased maternal investment in captive Japanese macaques (Macaca fuscatal using re productive and behavioural data. High-ranking mothers showed a significantl y male-biased secondary sex ratio, spent more time in contact with and carr ied male infants for longer than female infants. Low-ranking mothers showed no bias in secondary sex ratio nor in the time spent in contact with male and female infants, but carried female infants for longer. No differences w ere observed in the interbirth intervals following male and female infants nor in the frequency and intensity of aggression received by mothers with m ale and female infants, either in high-ranking or in low-ranking mothers. T hese results show that Japanese macaque mothers can adopt flexible and rank -dependent rearing strategies. Copyright (C) 1999 S. Karger AG, Baset.