1Anthropology, The Graduate Center, City University of New York, 2New York Consortium in Evolutionary Primatology, New York, 3Anthropology, Queens College, City University of New York, 4Filoha Hamadryas Project, Ethiopia
Friday 8:00-8:15, Ballroom A
Male hamadryas baboons are unusual among primates in focusing their reproductive effort on a small set of females in a one-male unit (OMU) rather than queuing for all estrous females as do other baboon males. Hamadryas males thus experience opportunity costs by failing to pursue additional females. Additional costs may derive from the presence in OMUs of follower males, who may gain sexual access to females. Here we explore the costs and benefits of this strategy in comparison to that of a closely related polygynandrous primate, the chacma baboon. Our data include seven years of observations of wild hamadryas baboons in Ethiopia and three years of chacma baboons in South Africa. Hamadryas leader tenure length averaged 44 months (N=69; an underestimate as most observations were censored), and leader males obtained 1-14 (mean 3.4) females overall and 1-8 sexually mature females (mean 2.8) during their tenure. We will compare the success of this exclusion strategy with that of chacma baboons, in which males compete for dominance rank and queue for estrous females. To further assess the costs and benefits of the hamadryas strategy, we will discuss the impact of follower males and size of OMUs on leader male tenure, the time interval between acquisition of successive females, and the number of infants born into their OMUs during their tenure as well as the survival of those infants. Via this comparison, we hope to elucidate the relative costs and benefits of multi-male queuing versus reproductive exclusion among male baboons.
Funded by the Leakey Foundation, the Wenner-Gren Foundation, the National Geographic Society, the National Science Foundation and the New York Consortium in Evolutionary Primatology (NYCEP).