Leaving Home: Demographic, Endocrine, And Behavioral Correlates Of Dispersal In Monogamous Owl Monkeys (aotus Azarae) Of Argentina

Natal dispersal, the movement of individuals from their birthplace to new areas in which they may breed, is an important aspect of life history that influences a variety of processes. Understanding dispersal not only increases our theoretical knowledge of the evolution of mating systems and social dynamics, but also provides insights essential for effective population management and for predicting the consequences that environmental changes may have on species’ distributions. This dissertation takes a holistic approach to explore natal dispersal at the level of the population, group, and individual in Azara’s owl monkey (Aotus azarae), a social monogamous primate native to South America. All data presented in this dissertation were collected at a long-term field site of the Owl Monkey Project in the Gran Chaco region of Formosa, Argentina. Chapter two examines dispersal at the level of the community, by exploring how demographic changes and environmental variables are associated with dispersal. The timing of dispersal was highly flexible, suggesting that delaying dispersal may be an adaptive strategy that owl monkeys utilize to minimize dispersal costs and maintain access to benefits provided by the natal group. Chapter three narrows the focus to the level of the group, and finds that behaviors, particularly agonism among group members, may function to regulate dispersal as well as mediate competition amongst adults and predispersed offspring. The next two chapters narrow the focus even further, to the individual level. Chapter four, which examines hormonal correlates of development and dispersal, finds that females experience the onset of sexual maturity prior to dispersing. Chapter five follows dispersing individuals thorough the entire process of dispersal to investigate the ultimate fates of dispersers. Dispersal strategies were highly variable, but individuals often prospected prior to permanently dispersing and almost always spent time as solitary “floaters”. Together, these investigations provide insight into both proximate and ultimate causes for dispersal and allow for the development of a multifaceted understanding of dispersal patterns in a socially monogamous primate. The holistic approach to understanding dispersal taken in this dissertation is one that could be useful for increasing our understanding of dispersal in many other taxa.