Reproductive seasonality in wild Sanje mangabeys (Cercocebus sanjei), Tanzania: Relationship between the capital breeding strategy and infant survival

Abstract

The reproductive seasonality model states that it is adaptive for species in seasonally variable environments to temporally cluster reproductive events around periods of resource availability. Many studies have examined links between seasonal reproduction and phenological events, though few studies have fully tested the adaptive hypothesis by examining the effects of reproductive timing on outcomes. Our study tests the predictions of the model in an African cercopithecine, the Sanje mangabey, by examining the impact of food availability on the timing of conception, birth and weaning, and the relationship of reproductive timing and female energy balance (urinary C-peptide) to infant survival. From September 2008 through 2010, 28 infants were born. Distribution of conceptions was non-uniform, with a peak between January and March. There was a significant positive correlation between mean monthly fruit availability and number of conceptions per month. An increased food supply supports a positive energy balance, maximizing the potential for conception; a pattern found among many cercopithecines. Mothers that conceived within the peak period also exhibited higher levels of urinary C-peptide during preconception and early gestation, compared to conceptions outside the peak period. This strategy increased the probability of survival to year one, as it was significantly higher for infants conceived during the peak conceptive season. These results support the reproductive seasonality model and demonstrate that the timing of conception is critical for mangabey reproductive success.