Abstract

The collective dynamics  of animal groups has attracted the attention of scientists across a broad range of fields. A variety of agent-based models have been proposed to describe the emergence of coordinated behavior from simple interaction rules. A simplifying assumption of many collective movement models, is that individual agents move with a constant speed. Here, we critically re-asses this assumption. Based on theoretical considerations accounting for inertia and rotational friction, we derive a functional dependence of the turning response of individuals on their instantaneous speed, which is confirmed by experimental data in different systems. We then investigate the interplay of variable speed and speed-dependent turning on self-organized collective behavior. Among others, we will show that besides the average speed of individuals, the variability in individual speed can have a dramatic impact on the emergent collective dynamics. Finally, we will discuss more broadly the role of adaptive speed for emergence of collective movement in models without explicit alignment interactions.