Abstract

Although primate females are predicted to develop counterstrategies against male infanticide, it has remained unclear whether counterstrategies are effective. Detailed long-term observations in Rhinopithecus roxellana reveal that females are able to mount versatile counterstrategies, including extra-unit mating, female joint defense and transfer with the infants, which lead to only 4 of 31 infants succumbing to infanticide and no difference in mortality of infants present during male replacements compare to other periods. Female joint defenses crucially delay infanticide and provide an opportunity for mothers' transfer to another social unit. In response to mothers' transfer, some males cease attacking infants, which is likely beneficial to males as during longer tenure they can sire future offspring of the mothers who remain. Our findings show how dynamic interactions between males and females can be and how the conditions in multilevel societies can shift the balance of intersexual conflict from males to females.