Modeling the emergence of seasonal fission-fusion dynamics in red-capped mangabeys (Cercocebus torquatus)

Abstract

Social systems can be defined based on their degree of fission-fusion dynamics, which depends on party characteristics (i.e., spatial cohesion, party size, and sex-age composition). Although the ecological and ethological causes of fission-fusion dynamics are still under revision, fruit availability seems to be a main factor in party formation in primates. We therefore explored ecological (i.e., fruit availability as an indicator of food competition) and ethological factors (i.e., travel distance) related to fission-fusion dynamics using our own agent-based simulation model. We compared the simulation results from the model with field data obtained from the movement patterns of a wild group of red-capped mangabeys (Cercocebus torquatus) (Dolado et al. 2016, Folia Primatol 87:197–212) and found that they were consistent with field data obtained on C. torquatus in that they showed similar patterns of seasonal fission-fusion dynamics. Moreover, the results suggest that the fission-fusion dynamics observed in simulations can match patterns of travel distance of arboreal species subject to food competition that reflects behavioral flexibility to adapt to environmental conditions shown by C. torquatus in the field. We have developed an agent-based model that reproduces the seasonal fission-fusion dynamics shown by a wild group of C. torquatus on the Atlantic coast of Gabon. The results of our simulations suggest that fission-fusion dynamics are an emergent behavior and that agent-based models are a good tool for exploring emergent behaviors in silico. Moreover, the agent-based simulation approach provides helpful new insights for future field studies on fission-fusion dynamics.