Infanticide and the value of male-female relationships in mountain chacma baboons

Associations between females and males over relatively long periods of time are common among savannah baboons (Papio cynocephalus). It seems clear that a female can benefit from close proximity to a male, since males are powerful partners in conflict situations with conspecifics and predators. For a male, proposed benefits of an association with a female are: (a) increased chances of mating with a female in the future through a positive effect on female choice and (b) increased fitness of the offspring sired with the female. In this study, data from a Drakensberg mountain chacma baboon troop (P. c. ursinus) were used to show that male-female associations were mainly between pregnant or lactating females and the putative Fathers of their offspring. In general, associations had no effect on male consort success. One observed and one suspected infanticide occurred during the study, suggesting that the main benefit of male-female associations derives from infanticide avoidance. An immigrated male was observed killing an infant sired prior to his residence and was suspected of killing another infant tired during his residence. I suggest that an unusual high degree of paternity certainty and long alpha-male tenure made infanticide an adaptive reproductive strategy for the highest-ranking male even after several months of residence in the group (infants were killed five and ten months after male immigration). While the highest-ranking male did not often interact with his infant, only the other two fathers carried their respective inferred offspring. This is interpreted as further evidence that infanticide avoidance is the primary factor leadint to long-lasting male-female associations.