Impact of male takeovers on infant deaths, births and conceptions in Cebus capucinus at Santa Rosa, Costa Rica

Male takeovers are associated with infant wounding and death in 3 of 4 capuchin species. In this paper, I analyze the effects of male takeovers on infant mortality and the subsequent conceptions and interbirth intervals of their mothers over an 18-yr period and test predictions of the sexual selection model of infanticide for white-faced capuchins, (Cebus capucinus). Major findings are that infants are significantly more likely to die in the 3- and 12-mo periods following a takeover than in times of peace and that a female whose infant dies experiences a significantly shorter interbirth interval before her next infant is born than she would have had the former infant survived. In the vast majority of cases, the invading males become resident in the group and are present during the subsequent conceptions of the females in the group. However, overall conception rates do not rise significantly in the year after a takeover, there is no relationship between the age of the infant at death and the length of the mother's subsequent interbirth interval, and it is not yet clear if male infants are preferentially targeted by invading males. Most takeovers occur during the 6-mo dry season and most conceptions occur in the wet season, 3- 6 mo later. My findings support the major predictions of the sexual selection model of infanticide in primates and demonstrate that male takeovers of social groups have substantial effects on infant survival and maternal parturition patterns in Cebus capucinus.