Reproductive socioecology of tufted capuchins (Cebus apella nigritus) in Northeastern Argentina

We describe the reproductive parameters of tufted capuchins (Cebus apella nigritus) in the Iguazu National Park, NE Argentina. We obtained data on six different groups (33 individually recognized adult females) studied for periods of 2-9 years. Estimated birthrate is 0.59 infants per female per year in unprovisioned groups. A group that was provisioned for 6 years during the winter period of low fruit availability (May-August), showed a similar birth rare of 0.61, but a lower infant mortality rate than unprovisioned groups The birthrate estimated for this population is higher than the one reported for white-faced and wedge-capped capuchins. The mean interbirth interval is 19.35 months, bur a female can have infants in successive years, even when her previous infant has survived. The modal age at first delivery is 7 years, which is similar to the one observed in wedge-capped capuchins. When young adult females come into estrous they avoid copulating with the alpha male that sired them, thus providing evidence for a behavioral mechanism of inbreeding avoidance. Births are very seasonal at Iguazu, occurring during the spring and summer months (October-February) when food availability is at its peak. Tufted capuchins at Iguazu are more seasonal breeders than other capuchin populations, probably as a result of their more seasonal environment. The secondary sex ratio does not deviate significantly from 1:1, despite the known ability of capuchins to adjust secondary sex ratio to local conditions.