Study on social patterns and information transmission in schools of fish

Moving animal groups, such as flocks of birds, schools of fish, insect swarms, herds of mammals, and human crowds, exhibit intricate and highly coordinated behaviors. This thesis explores the underlying mechanisms of collective behavior by analyzing extensive, high-resolution experimental data of trajectories of schooling fish in a controlled environment.

We first introduce the existence of temporal leadership dynamics based on relative speeds, a hypothesis we support through both agent-based modeling and analysis of leader-follower relationships in the experimental data. Next, we examine how variations in perceived risk influence the behavior and interactions of fish within a group. We also investigate spontaneous behavioral cascades in schooling fish, focusing on turning avalanches, where large directional shifts are propagated through the group. Finally, we explore and extend the nearest-neighbor declustering technique for analyzing aftershock correlations in point processes. 

Overall, this thesis provides novel insights into the mechanisms driving collective behavior in animal groups, emphasizing the role of selective social interactions and critical dynamics. Our empirical, data-driven approach highlights the complexity of animal collectives and lays a foundation for future studies on collective decision-making, leadership, and information transfer in biological systems.