Collective motion as a distinct behavioural state of the individual

Summary The collective motion of swarms depends on adaptations at the individual level. We explored these and their effects on swarm formation and maintenance in locusts. The walking kinematics of individual insects were monitored under laboratory settings, before, as well as during collective motion in a group, and again after separation from the group. It was found that taking part in collective motion induced in the individual unique behavioural kinematics, suggesting the existence of a distinct behavioural mode that we term a "collective-motion-state". This state, characterized by behavioural adaptation to the social context, is long lasting, not induced by crowding per-se, but only by experiencing collective motion. Utilizing computational models, we show that this adaptability increases the robustness of the swarm. Overall, our findings suggest that collective-motion is not only an emergent property of the group, but also depends on a behavioural mode, rooted in endogenous mechanisms of the individual.