Scale-free correlations in starling flocks

By Andrea Cavagna, A. Cimarelli, Irene Giardina, Giorgio Parisi, Raffaele Santagati, Fabio Stefanini, Massimiliano Viale. Proceedings of the National Academy of Sciences of the United States of America, 2009

1,017 citations recorded by the source corpus.

From bird flocks to fish schools, animal groups often seem to react to environmental perturbations as if of one mind. Most studies in collective animal behavior have aimed to understand how a globally ordered state may emerge from simple behavioral rules. Less effort has been devoted to understanding the origin of collective response, namely the way the group as a whole reacts to its environment. Yet, in the presence of strong predatory pressure on the group, collective response may yield a significant adaptive advantage. Here we suggest that collective response in animal groups may be achieved through scale-free behavioral correlations. By reconstructing the 3D position and velocity of individual birds in large flocks of starlings, we measured to what extent the velocity fluctuations of different birds are correlated to each other. We found that the range of such spatial correlation does not have a constant value, but it scales with the linear size of the flock. This result indicates that behavioral correlations are scale free: The change in the behavioral state of one animal affects and is affected by that of all other animals in the group, no matter how large the group is. Scale-free correlations provide each animal with an effective perception range much larger than the direct interindividual interaction range, thus enhancing global response to perturbations. Our results suggest that flocks behave as critical systems, poised to respond maximally to environmental perturbations.

Subfields: Ecology, Evolution, Behavior and Systematics, Genetics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/123b18feab79d9cf235fc273f4c1c1542551b3da

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Ecology, Evolution, Behavior and Systematics

In Genetics

In Global and Planetary Change

Citations in the corpus

Colloquium: Criticality and dynamical scaling in living systems (2017, background): “On the empirical side, pioneering work by Cavagna, Giardina and collaborators (Ballerini et al., 2008; Cavagna et al., 2010) on starling flocks allowed to record individual trajectories (with purposely devised tracking technology).”
How simple rules determine pedestrian behavior and crowd disasters (2011, positive): “The greater explanatory power of our heuristics-based modeling, as demonstrated through comparison with different empirical and experimental data (see the overview in Table S1), suggests a paradigm shift from physics-inspired binary interaction models to an integrated treatment of multiple interacti”
Inferring the structure and dynamics of interactions in schooling fish (2011, background): “(26) have used the spatial structure of starling flocks to infer that starlings use topological rather than metric interactions and that information is transferred over large distanceswithin flocks in a scale-free manner.”
The statistical physics of active matter: From self-catalytic colloids to living cells (2017, background): “The transition becomes continuous when alignment occurs through topological interactions, as reported in bird flocks [67, 68, 66], or when adding birth and death reactions [69].”
Temperature in and out of equilibrium: A review of concepts, tools and attempts (2017, background): “Interestingly, a role of a certain relevance has been played by equilibrium-like or equilibrium-inspired models, where the intrinsic non-equilibrium condition of active systems has been neglected or drastically reduced [301,297].”
Criticality in the brain: A synthesis of neurobiology, models and cognition. (2017, background): “The signatures of criticality have been documented in systems as diverse as flocking birds (Cavagna et al., 2010), earthquakes (Burridge and Knopoff, 1967; Carlson and Langer, 1989; Rice and Ruina, 1983); solar flares (Lu et al., 1993), armed conflict (Roberts and Turcotte, 1998), traffic jams…”
Emergent complex neural dynamics (2010, background): “As such, critical dynamics have been documented in species evolution [1], ants collective foraging [32, 33] and swarm models [34], bacterial populations [35], traffic flow in highways [1] and on the Internet [10], macroeconomic dynamics [7], forest fires [8], rainfall dynamics [11–13] and flock form”
Meso-scale turbulence in living fluids (2012, background): “, flocks of birds (12) or schools of fish (13, 14)] and present important biological model systems to study nonequilibrium phases and their transitions (15–17).”