Reproductive ecology of the Sanje mangabey in the Udzungwa Mountains, Tanzania

Reproductive seasonality is an evolutionary adaptation that fosters successful reproduction for females living in dynamic ecological conditions. There are two general patterns: income breeding (births coincide with predictable peaks in food availability), and capital breeding (conceptions cluster in the high food period, which can be unpredictable). The objectives of this dissertation are (1) to determine if Sanje mangabeys, Cercocebus sanjei, display reproductive seasonality; (2) to evaluate whether reproductive seasonality impacts female reproductive success and (3) the methods by which this is achieved; and (4) to identify the consequences of reproductive seasonality, with respect to gastrointestinal parasite risk. Sanje mangabeys displayed the capital breeding strategy. During the high food period, they increased the proportion of dietary fat, which increased their energetic condition. In doing so, they also increased their estradiol levels prior to conception, stored energy for use during the expensive periods of late gestation and early lactation, and improved their physical condition during mid-lactation (one year after conception). Consequently, these females had higher infant survival compared to females that conceived in the low food period. Capital breeding also increased parasite infection risk. Females in preconception and mid-lactation had significantly higher parasite richness and prevalence compared to other reproductive states, as a product of lower energetic condition (increased host susceptibility) and higher rainfall (increased host exposure). Taken together, the results of this dissertation demonstrate that energetic condition and reproduction are closely linked, and despite the costs of increased parasite infection risk, capital breeding increases reproductive success in Sanje mangabeys.