Male parental care, female choice and the effect of an audience in vervet monkeys

The parental behaviour of male vervet monkeys, Cercopithecus aethiops, was examined to determine whether (1) females respond to the parental behaviour of males and (2) males vary the amount of parental care they provide depending upon the presence of the infant's mother. Eleven males and 11 infants from four groups were observed under dyadic conditions in which the male could or could not see the infant's mother. Males, particularly subordinate males, altered their rates of affiliative and agonistic behaviour towards infants depending upon the perceived presence or absence of the infant's mother. Females varied their affiliative and agonistic behaviour towards males depending upon male dominance status, and the male's behaviour towards the infant. There is growing evidence that female mate choice is an important evolutionary force in non-human primates (chimpanzees, Pan troglodytes: Turin 1979; brown capuchins, Cebus apella: Jansen 1984; baboons, Papio anubis: Smuts 1985; vervets, Cercopithecus aethiops: Andelman 1985; Keddy 1986), yet there is still controversy concerning the criteria females use to choose mates. Several studies have suggested that females may prefer dominant males (baboons, Papio cynocephalus: Seyfarth 1978a, b; macaques, Macaca spp.: Robinson 1982; reviewed in Silk & Boyd 1983). There is also evidence that high-ranking females may influence male rank by preferentially socializing with, or aiding particular males in agonistic confrontations (rhesus macaques, Macaca mulatta: Chapais 1983; Pigtail macaques, Macaea nemestrina: Gouzoules 1980; vervets: Raleigh et al. 1982; chimpanzees: deWaal 1982). Female mating preferences may therefore be determined by more than dominance per se. Females may also prefer males who provide parental care. In many species of Old World monkeys, males form strong protective relationships with females and their young (baboons: Seyfarth 1978b; Altmann 1980; Johnson 1984; Stein 1984; Smuts 1985). Such relationships may reduce the harassment that the female and her young receive from other members of the group and may decrease competition over food. Bonds between males and infants are often associated with 'special relationships' between males and females (baboons: Smuts 1983), so that when a female resumes sexual cycling, she is more likely to mate with the male than she might have been otherwise (baboons: Seyfarth 1978a, b; Rasmussen 1980, 1983; Smuts 1985; Japanese macaques, Macaea fuseata: Takahata 1982). Whether the male's relationship with the infant's mother is a step towards, or a consequence of, the male's association with the infant is difficult to discern (Whitten 1987). However, researchers have suggested that male infant affiliation is quite likely to affect subsequent female mate choice (Smuts 1985; Whitten 1987). Therefore, male parental behaviour can potentially be viewed as a strategy adopted by males to influence female mate choice. Parental behaviour might be expected to be particularly strong among low-ranking males who could use this behaviour to counteract their poor competitive abilities (Strassmann 1981). If females base their mating preferences on traits such as male parental care, then females should alter their behaviour toward males depending upon their past interactions with them. To test this hypothesis, we designed a series of experiments that investigated how prior interactions between males and infants affect subsequent behaviour between the male and the infants' mothers. The hypothesis that female preferences depend upon traits such as male parental care also predicts 0003-3472/89/080262+ l0 $03.00/0 9 1989 The Association for the Study of Animal Behaviour