The Socioecological Correlates of Collective Movements in Giraffes

Abstract How collective behaviors emerge from group members with potentially divergent needs remains poorly understood in many social species. Giraffes are known to exhibit substantial social fluidity, given the high degree of fission-fusion dynamics that shape their grouping patterns. However, the patterns and processes underlying giraffe collective movements remain unknown. Using behavioral observations, we examined how individual factors (sex and age), social context (group size and type), and habitat characteristics (open and closed) influence the decision-making process that shapes giraffe collective movements and resultant group fission. We found that adult females were more likely to initiate group movements, whereas subadults followed movements more quickly than other age classes. Decision-making for collective movements was slower in larger groups than in smaller ones. Consequently, movements in larger groups were more likely to result in group fission. These results contribute to a growing body of knowledge on the coordination of collective movement across species. By illuminating collective movement dynamics in an understudied large mammal species with a high degree of fission-fusion dynamics, we contribute to the potential for cross-species investigations into the mechanisms of collective behavior and the factors that drive inter- and intraspecific variation.