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Abstract

Males may increase their fitness by providing care to offspring or to unrelated infants of female “friends” to maximise future mating. The potential for paternal care depends on paternity certainty, particularly in multi-male, multi-female groups with polygynandrous mating. In crested macaques (Macaca nigra), there seems to be high potential for paternity certainty and need for paternal protection. However, male-mother affiliation (or “friendships”), not paternity, predicts male-infant affiliation, questioning whether males can identify their offspring reliably. Using a Bayesian approach, we investigated male responses to infant screams (N = 2,637) emitted during agonistic interactions with males being the friend of the infant, the friend of the infants’ mother, and/or the father of the infant. Overall, male responses to infant screams were low. Bayesian estimates showed considerable uncertainty; hence, results should be interpreted cautiously. However, males were slightly more likely to react if the infant or its mother was a friend of the male or if the infant was his offspring. Additionally, higher-ranking males were slightly more likely to respond than lower-ranking ones, and screams from infants of lower-ranking females were more likely to be responded to. This might indicate that males assess paternity based on their rank and that they assess the need to intervene. Given the limitations of our study and the uncertainty surrounding our results, future studies are needed before we can draw solid conclusions for crested macaques. Overall, our results are in line with other studies suggesting that male primates provide care to related and unrelated infants.