How Many for Lunch Today? Seasonal Fission-Fusion Dynamics as a Feeding Strategy in Wild Red-Capped Mangabeys...

For group-living primates, social organization hinges upon multiple factors, including group size, group cohesion, and the group's age and sex composition. Fission-fusion dynamics reduce the risks of living in a large group, which can include feeding competition related to the seasonality of resources. Here we report on the group dynamics (i.e. formation of parties) of a population of red-capped mangabeys (Cercocebus torquatus) located in Sentier Nature forest, South Loango National Park, Gabon, and examine the role of fruit availability in episodes of fission-fusion and shifting range use during the peak fruiting season of 2014. To assess fission-fusion dynamics, we obtained data on party type (i.e. number, size and age-sex composition), the effect of availability of fruit from 4 tree species on the home range and habitat used by parties, and the periodicity of these processes. The results show that red-capped mangabeys displayed seasonal fission-fusion dynamics related to fruit availability during the season under study.