Social interactions dominate speed control in poising natural flocks near criticality

Flocks of birds exhibit a remarkable degree of coordination and collective response. It is not just that thousands of individuals fly, on average, in the same direction and at the same speed, but that even the fluctuations around the mean velocity are correlated over long distances. Quantitative mea...

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Veröffentlicht in:Proceedings of the National Academy of Sciences - PNAS Jg. 111; H. 20; S. 7212
Hauptverfasser: Bialek, William, Cavagna, Andrea, Giardina, Irene, Mora, Thierry, Pohl, Oliver, Silvestri, Edmondo, Viale, Massimiliano, Walczak, Aleksandra M
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States 20.05.2014
Schlagworte:
Animals
Behavior, Animal
Entropy
Flight, Animal - physiology
Models, Theoretical
Movement
Social Behavior
Starlings - physiology
collective behavior
statistical mechanics
ISSN:1091-6490, 1091-6490
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Zusammenfassung:Flocks of birds exhibit a remarkable degree of coordination and collective response. It is not just that thousands of individuals fly, on average, in the same direction and at the same speed, but that even the fluctuations around the mean velocity are correlated over long distances. Quantitative measurements on flocks of starlings, in particular, show that these fluctuations are scale-free, with effective correlation lengths proportional to the linear size of the flock. Here we construct models for the joint distribution of velocities in the flock that reproduce the observed local correlations between individuals and their neighbors, as well as the variance of flight speeds across individuals, but otherwise have as little structure as possible. These minimally structured or maximum entropy models provide quantitative, parameter-free predictions for the spread of correlations throughout the flock, and these are in excellent agreement with the data. These models are mathematically equivalent to statistical physics models for ordering in magnets, and the correct prediction of scale-free correlations arises because the parameters--completely determined by the data--are in the critical regime. In biological terms, criticality allows the flock to achieve maximal correlation across long distances with limited speed fluctuations.
Bibliographie:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.1324045111