Interactions of a Captive Maturing Female Hamadryas Baboon

In the wild, hamadryas baboons (Papio hamadryas hamadryas) typically practice male philopatry, where females transfer out of natal units to avoid inbreeding (Swedell et al. 2011). However, little is known about hamadryas female transfer in captivity. In this study, we used focal animal sampling (Altmann 1974) to observe female transfer in a captive group comprised of two one-male units. The group includes a subadult female, whom we expected to transfer to the non-natal unit soon after reaching sexual maturity. We recorded the proximity between the subadult female and all other individuals, as well as affiliative and agonistic behavior exhibited between them. Although the size of the enclosure forces all individuals to be closer to each other than they may be in the wild, we hypothesized that the female would act in accordance with wild populations in transferring out of her natal group and practicing inbreeding avoidance (Swedell et al. 2011). Preliminary results show that at this time, the subadult female is still spending, on average, a greater percent of her time with her natal unit than with the non-natal unit. However, data collection needs to be continued for a longer period of time to determine whether or not a trend in proximity or behavior is present. INTRODUCTION In the wild it is typical for female hamadryas baboons to leave their natal families, also called one-male units, to join another. The family is the smallest of the species' social organization, which is divided into multiple levels. The next largest level consists of many one-male units headed by related males (Mori et al. 2007). This level of society is referred to as a band in most studies, but research performed on one group of hamadryas baboons in Erer-Gota, Ethiopia, recognized an additional level between the family and band, which they referred to as the clan (Swedell 2002). The final, and largest group, is called the troop. It consists of multiple bands (Mori et al. 2007). This multi-level social structure is unique to Papio hamadryas hamadryas, and serves multiple purposes. At night, all one-male units come together on sleeping cliffs to protect themselves from predators (Kummer 1968). During the day, bands break apart from the troop to forage. This allows all individuals to get enough food in the sparsely vegetated regions in which they occur in the wild. If food availability is especially low, one-male units will separate from each other within the band (Schreier and Grove 2010). The flexibility of the multi-level social structure provides hamadryas baboons with several advantages in the arid semi-desert region of north eastern Africa where they live (Altmann 1974). In order to maintain this multi-level social structure, sexually mature males must leave their natal units and start initial units, the beginning of their family. The males in these families typically find mates outside the clan or band level to avoid inbreeding. Sometimes adult males bring adult females into preexisting units. This process typically involves violence between the female's mate and the challenger male, thus making it less common than other forms of female transfer (Kummer 1995). More commonly, young males start initial units with a juvenile or subadult female, which can be accomplished in a few different ways. One way in which initial units are formed is when a follower, a subadult male attached to a onemale unit, kidnaps and begins herding an infant or juvenile female. As subadult males, followers typically have little chance of acquiring an adult female from an adult male by force, so they pursue more easily attainable sexually immature females. The subadult male takes the young female from her natal unit and cares for her like a mother until she reaches sexual maturity, when he can successfully mate with her. This tactic works particularly well for subadult males because there is little competition over sexually