Scale-free behavioral cascades and effective leadership in schooling fish

• Published in: arXiv.org
• Main Authors: Mugica, Julia, Torrents, Jordi, Cristin, Javier, Puy, Andreu, Miguel, M Carmen, Pastor-Satorras, Romualdo
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 13.10.2022
• Subjects: Avalanches; Behavior; Cascades; Fish; Leadership; Physics - Adaptation and Self-Organizing Systems; Physics - Biological Physics; Physics - Statistical Mechanics; Trajectories
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2203.05473

Behavioral contagion and the presence of behavioral cascades are natural features in groups of animals showing collective motion, such as schooling fish or grazing herbivores. Here we study empirical behavioral cascades observed in fish schools defined as avalanches of consecutive large changes in the heading direction of the trajectory of fish. In terms of a minimum turning angle introduced to define a large change, avalanches are characterized by distributions of size and duration showing scale-free signatures, reminiscent of self-organized critical behavior. We observe that avalanches are generally triggered by a small number of fish, which act as effective leaders that induce large rearrangements of the group's trajectory. This observation motivates the proposal of a simple model, based in the classical Vicsek model of collective motion, in which a given individual acts as a leader subject to random heading reorientations. The model reproduces qualitatively the empirical avalanche behavior observed in real schools, and hints towards a connection between effective leadership and avalanche behavior in collective movement.