Reproductive Ecology and Behavioral Endocrinology of Owl Monkeys

This chapter reviews and synthesizes research on hormonal correlates of sexual maturation and adult reproductive function in owl monkeys and how those hormones respond to changes in the social and physical environment. We first briefly summarize the methods that have been utilized to assess hormone metabolite concentrations and the methodological challenges researchers currently face, both in the field and in the laboratory. We consider initially what we know from studies of captive individuals, which have examined different species and are the source of most data. We follow with a presentation of the insights into the reproductive ecology and behavioral endocrinology of owl monkeys in a wild population of Azara’s owl monkey (Aotus azarae) in Formosa, Argentina, and discuss how these data may inform our understanding of pair formation, pair-bonding, and parental care in pair-living and sexually monogamous taxa. While knowledge of the reproductive and behavioral endocrinology of wild owl monkeys is still emerging, ovarian cycles in adult females and associations between cortisol and biparental care in both sexes have been well described. Monitoring of wild subadult females has indicated that the onset of ovarian cycling commences prior to dispersing, which suggests that, in contrast to some callitrichids, subadult female owl monkeys do not experience endocrine suppression. Our understanding of the endocrine correlates of male reproductive behavior and seasonal variation in reproductive hormones is still being developed.