Predation and Male Bonds in Primate Societies

Abstract

[In this paper I consider the effects of predation in relation to other evolutionary influences on the social systems of nonhuman primates, in particular on the evolution of male bonds in multimale primate groups. Because of the difficulty of documenting its infrequent occurrence, predation on wild nonhuman primates has rarely been studied and its effects on behaviour are poorly understood. Male bonds have also been neglected compared to female bonds in studies of primate societies. Of the accepted evolutionary influences on male bonds — the distribution of females, enhanced individual reproductive success that comes from the control of females, predator avoidance, and protection from intergroup aggression by conspecifics — predation is the only one of these that typically ends all future individual lifetime fitness. I review the widely held hypotheses for the formation of male bonds and consider the extent to which predation has been an evolutionary influence on their formation. It appears that male-bonding for the purpose of repelling predators is not necessarily based on the kin-selected benefits often attributed to cooperative behavior among primates. I also discuss predation risk and predation mortality as agents of natural selection on social behavior. Data are presented from a field study on the effect of predation on the behavioural ecology and demography of one male-bonded primate species, the red colobus monkey (Colobus badius). Field data show that the influence of predation on the red colobus social system appears to be mitigated by behavioral tradeoffs. Predation is a demonstrably strong influence on the structure of some primate societies, but its effects vary widely between species. Male bonding is one response to the risk of predation, but does not appear to be based on kin-selected benefits to the participants in most species., In this paper I consider the effects of predation in relation to other evolutionary influences on the social systems of nonhuman primates, in particular on the evolution of male bonds in multimale primate groups. Because of the difficulty of documenting its infrequent occurrence, predation on wild nonhuman primates has rarely been studied and its effects on behaviour are poorly understood. Male bonds have also been neglected compared to female bonds in studies of primate societies. Of the accepted evolutionary influences on male bonds — the distribution of females, enhanced individual reproductive success that comes from the control of females, predator avoidance, and protection from intergroup aggression by conspecifics — predation is the only one of these that typically ends all future individual lifetime fitness. I review the widely held hypotheses for the formation of male bonds and consider the extent to which predation has been an evolutionary influence on their formation. It appears that male-bonding for the purpose of repelling predators is not necessarily based on the kin-selected benefits often attributed to cooperative behavior among primates. I also discuss predation risk and predation mortality as agents of natural selection on social behavior. Data are presented from a field study on the effect of predation on the behavioural ecology and demography of one male-bonded primate species, the red colobus monkey (Colobus badius). Field data show that the influence of predation on the red colobus social system appears to be mitigated by behavioral tradeoffs. Predation is a demonstrably strong influence on the structure of some primate societies, but its effects vary widely between species. Male bonding is one response to the risk of predation, but does not appear to be based on kin-selected benefits to the participants in most species.]