Abstract

When performing essential collective tasks, such as foraging, social insect societies can easily coordinate their movement and facilitate navigation through complex environments. In social insects, colonies manage to efficiently move from place to place by establishing a series of interconnected self-organized pathways. However, while the chemistry behind the emergence of such ‘roads’ has been well described, little is known about behavioural mechanisms modulating not only the emergence but also the maintenance of such collective patterns. In this research, we developed an empirical framework to investigate the underlying mechanisms of coordinated collective motion in social insects. To test whether complex societies exhibit fixed or adaptive movement rules, we focus on two intrinsic measurable parameters of group structure: group size and group composition. Combining high-resolution videos and computer-vision techniques, we map individual trajectories and extract the number of encounters and interactions between individuals in a group. Our results provide evidence that colonies may switch between behavioural states and suggest that spatiotemporal dynamics in group structure have a significant impact on individual behaviour, and consequently, on collective outcomes. The transitional behaviour and multi-stability we observe reinforces the view of social insects as excellent models for studying mechanisms of collective behaviour.