Abstract

Animals living in stable and cohesive groups acquire critical resources for survival while moving together. These groups can vary in size and composition, facing challenges induced by environmental heterogeneity. To shed light on the effects of the social and physical environment on collective behavior, I studied groups of vulturine guineafowl (Acryllium vulturinum) in the Kenyan savannah using high-resolution GPS tracking, field observations, video tracking, and environmental data. My collaborative work demonstrates that vulturine guineafowl, as well as other bird species, can form multilevel societies where stable groups associate preferentially, forming super-groups. Inter-group associations in turn are shaped by habitat features and seasonality. Guineafowl groups of intermediate size exhibit optimal ranging behavior and higher reproductive success. Extreme environmental conditions, such as droughts, significantly expand the areas used by the groups. Despite changing environments, guineafowl maintain cohesion through shared decision-making, ensuring that group members satisfy their needs, even during conflicts over food. Collective responses to emerging inequality during such conflicts play a crucial role in maintaining the benefits of group-living across species. Overall, this study highlights the shaping of outcomes and dynamics of collective behavior in wild group-living animals through the interaction between the social and physical environment.