Baboon females commonly mate with multiple males during a given estrus period (time of sexual receptivity around ovulation) and are thus described as promiscuous in their mating behavior (Hall 1962; Hall and DeVore 1965; Saayman 1970; Hausfater 1975a; Seyfarth 1978a; Smuts 1985; Bercovitch 1987b, 1995). Despite the larger body size and dominance of male baboons, most female baboons are able to express their mating preferences, i.e., exert choice in mating (Halliday 1983; Small 1989), in that they may initiate or refuse copulations with males (Hall 1962; Hausfater 1975a; Seyfarth 1978a; Scott 1984; Smuts 1985; Bercovitch 1991). Females may also circumvent mating strategies of other individuals by engaging in surreptitious copulations with lower-ranking males. Although not generally very selective in their choice of mates, females sometimes exhibit preferences for unfamiliar or newly immigrated males (Bercovitch, 1991, 1992).
Baboon female reproduction is also influenced by competition with other females (Seyfarth 1976; Wasser 1983; Barton 1993). In yellow baboons, for example, aggressive coalitions among females increase in frequency with the number of simultaneously estrous females (Wasser 1983; Wasser and Starling 1986). In olive baboons, follicular phases are longer than usual in females who suffer severe aggression from other females before, during, or just after menstruation (Rowell 1970). Interestingly, Dunbar and Sharman (1983) found a negative correlation between adult sex ratio and birth rate in olive, yellow, and chacma baboons: i.e., the more females in a group relative to males, the lower the birth rate, implying that there are a limited number of reproductive positions in the group. Similarly, Zinner et al (1994) found that the degree of estrus synchrony within captive hamadryas one-male units was lower during conceptive compared to nonconceptive cycles, suggesting that the sperm of hamadryas leader males is in limited supply (a real possibility given that hamadryas testes are smaller than those of other baboons; Small 1988; Phillips-Conroy and Jolly 2006) or that females vary in their access to the leader male during estrus.
Content contributed by:
Dr Larissa Swedell
|Thanks to the following reviewers:
Dr Susan Alberts
Dr Cliff Jolly
For a more scholarly version of the information on these pages, see:
Swedell, L (2011) African Papionins: Diversity of Social Organization and Ecological Flexibility. IN Primates in Perspective, Second Edition (Campbell CJ, Fuentes A, MacKinnon KC, Bearder SK, Stumpf, RM, eds). New York: Oxford University Press, pp. 241-277.
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