Our current research at Filoha focuses on the interface between biology and behavior in hamadryas baboons. For example, having found that female social relationships may be more important than previously thought (Swedell 2002), we are now investigating whether patterns of social bonding and movement among social units are influenced by biological kinship. Results from the PhD work of Veronika Städele (in Linda Vigilant's lab at the Max Planck Institute) suggest that hamadryas females seek their kin whenever possible (Staedele et al. 2015, 2016). We also plan to use behavioral, genetic and hormonal data to investigate the adaptive value of social bonds among females, among males, and between the sexes, i.e., how variation in social bonding is linked with other factors, particularly those associated with fitness benefits (as has been shown by Silk et al. 2003, 2009, 2010 for other baboon subspecies). In addition, we are continuing our work on reproductive strategies with the PhD work of Alexis Amann, which focuses on the fitness costs of male takeovers and female counterstrategies. Further characterization of both male and female reproductive strategies in the hamadryas social system hinges on a determination of the leader male's share of paternity of the infants born into his one-male unit, which remains an open question. Hamadryas leader males make strenuous efforts to maintain exclusive access to the females in their one-male units, but females do copulate with other males surreptitiously. We do not yet know, however, how often these surreptitious copulations lead to conception.
Over the past decade or so, we have been focusing on the role of follower males in hamadryas society. Prior to becoming leader males of OMUs, males may be solitary males, e.g., unaffiliated bachelors, or follower males, e.g., males that are subordinate to leaders but consistently associated with a particular OMU. Within this system, it seems fairly certain that most males eventually gain females and become leaders, even though solitary and follower males often use different strategies to do so (Pines et al. 2011, 2015). It is not yet clear, however, why, on the path to that role, some males remain solitary and others become followers. Genetic data from Veronika Staedele's PhD work confirms previous speculations that leaders and followers are often close relatives (Staedele et al. 2016), and additional analyses by Shahrina Chowdhury demonstrate clear fitness benefits of followers for leaders (Chowdhury et al. 2015).
The latest step forward in our ongoing research at Filoha was the fitting of satellite collars on hamadryas males in July 2015 and October 2016. With the generous support of the National Zoo (Smithsonian Institution, Washington, D.C., USA), the Fort Worth Zoo (Forth Worth, TX, USA), and the Wildlife Conservation Society (USA), we were able to bring wildlife veterinarians Dr. Carlos Sanchez and Dr. Dawn Zimmerman to Filoha to assist with this effort. Our most persistent problem at Filoha for two decades has been our inability to locate our study subjects, as each band's home range is exceptionally large and they use multiple sleeping sites, many of which are difficult to access. Being able to track the baboons using satellite technology is thus a major milestone in our research at Filoha and will open the door to far more detailed studies of the biology of these incredible animals than have ever been possible before.
all text and photos copyright © Larissa Swedell