Emergence of collective changes in travel direction of starling flocks from individual birds' fluctuations

Attanasi, Alessandro; Cavagna, Andrea; Castello, Lorenzo Del; Giardina, Irene; Jelić, Asja; Melillo, Stefania; Parisi, Leonardo; Pohl, Oliver; Shen, Edward; Viale, Massimiliano

doi:10.1098/rsif.2015.0319

Cited by 70 publications

(76 citation statements)

References 30 publications

(72 reference statements)

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“…Therefore, frontal individuals are more subjects to heading fluctuations and less inhibited to initiate U-turns. Similarly, in starling flocks, the birds that initiate changes in collective travelling direction are found at the edges of the flock [35].…”

Section: Discussionmentioning

confidence: 99%

Domino-like propagation of collective U-turns in fish schools

Lecheval

Jiang

Tichit

et al. 2017

Preprint

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Moving animal groups such as schools of fish or flocks of birds often undergo sudden collective changes of their travelling direction as a consequence of stochastic fluctuations in heading of the individuals. However, the mechanisms by which these behavioural fluctuations arise at the individual level and propagate within a group are still unclear. In the present study, we combine an experimental and theoretical approach to investigate spontaneous collective U-turns in groups of rummy-nose tetra (Hemigrammus rhodostomus) swimming in a ring-shaped tank. U-turns imply that fish switch their heading between the clockwise and anticlockwise direction. We reconstruct trajectories of individuals moving alone and in groups of different sizes. We show that the group decreases its swimming speed before a collective U-turn. This is in agreement with previous theoretical predictions showing that speed decrease facilitates an amplification of fluctuations in heading in the group, which can trigger U-turns. These collective U-turns are mostly initiated by individuals at the front of the group. Once an individual has initiated a U-turn, the new direction propagates through the group from front to back without amplification or dampening, resembling the dynamics of falling dominoes. The mean time between collective U-turns sharply increases as the size of the group increases. We develop an Ising spin model integrating anisotropic and asymmetrical interactions between fish and their tendency to follow the majority of their neighbours nonlinearly (social conformity). The model quantitatively reproduces key features of the dynamics and the frequency of collective U-turns observed in experiments.

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Section: Discussionmentioning

confidence: 99%

Domino-like propagation of collective U-turns in fish schools

Lecheval

Jiang

Tichit

et al. 2017

Preprint

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“…Bacterial suspensions [1], cellular monolayers [2] and sub-cellular filament/motor-protein mixtures [3,4] are continuously driven far from equilibrium through intrinsic energy injection by their biological constituent elements. This microscopic energy input can result in the spontaneous emergence of large-scale collective behaviour, including flocking [5][6][7], unidirectional flows [8], meso-scale turbulence [1,9,10], topological defect pair production [11][12][13], and phase separation [14]. Moreover there is a rapidly growing list of biological systems, including anterior-posterior establishment by active cytoplasmic streaming in oocytes [15], pupal wing morphogenesis [16], wound healing [17,18], and cancer invasion [19,20], that has been identified as leveraging collective flows for active self-organisation.…”

Section: Introductionmentioning

confidence: 99%

Dancing disclinations in confined active nematics

Doostmohammadi²,

et al. 2017

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The spontaneous emergence of collective flows is a generic property of active fluids and often leads to chaotic flow patterns characterised by swirls, jets, and topological disclinations in their orientation field. However, the ability to achieve structured flows and ordered disclinations is of particular importance in the design and control of active systems. By confining an active nematic fluid within a channel, we find a regular motion of disclinations, in conjunction with a well defined and dynamic vortex lattice. As pairs of moving disclinations travel through the channel, they continually exchange partners producing a dynamic ordered state, reminiscent of Ceilidh dancing. We anticipate that this biomimetic ability to self-assemble organised topological disclinations and dynamically structured flow fields in engineered geometries will pave the road towards establishing new active topological microfluidic devices.

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“…Information transfer is of particular relevance for collective behaviour, where it has been observed that small perturbations cascade through an entire group in a wave-like manner [62,63,34,3], with these cascades conjectured to embody information transfer [73]. This phenomenon is related to underlying causal interactions, and a common goal is to infer physical interaction rules directly from experimental data [36,30,35] and measure correlations within a collective.…”

Section: Introductionmentioning

confidence: 99%

Informative and misinformative interactions in a school of fish

et al. 2018

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It is generally accepted that, when moving in groups, animals process information to coordinate their motion. Recent studies have begun to apply rigorous methods based on Information Theory to quantify such distributed computation. Following this perspective, we use transfer entropy to quantify dynamic information flows locally in space and time across a school of fish during directional changes around a circular tank, i.e. U-turns. This analysis reveals peaks in information flows during collective U-turns and identifies two different flows: an informative flow (positive transfer entropy) based on fish that have already turned about fish that are turning, and a misinformative flow (negative transfer entropy) based on fish that have not turned yet about fish that are turning. We also reveal that the information flows are related to relative position and alignment between fish, and identify spatial patterns of information and misinformation cascades. This study offers several methodological contributions and we expect further application of these methodologies to reveal intricacies of self-organisation in other animal groups and active matter in general. * emanuele.crosato@sydney.edu.au arXiv:1705.01213v1 [q-bio.QM] 3 May 2017 Nagy et al. [55] used a variety of correlation functions to measure directional dependencies between the velocities of pairs of pigeons flying in flocks of up to ten individuals, reconstructing the leadership network of the flock. As has been shown later, this network does not correspond to the hierarchy between birds [56]. Information transfer has been extensively studied in flocks of starlings, by observing the propagation of direction changes across the flocks [20,19,2]. More recently, Rosenthal et al. [69] attempted to determine a communication structure of a school of fish during its collective evasion manoeuvres manifested through cascades of behavioural change. A functional mapping between sensory inputs and motor responses was inferred by tracking fish position and body posture, and calculating visual fields.Rather than consider semantic or pragmatic information, many contemporary studies employ rigorous information theoretic measures that quantify information as uncertainty reduction, following Shannon [24], in order to deal with the stochastic, continuous and noisy nature of intrinsic information processing in natural systems [28]. Distributed information processing is typically dissected into three primitive functions: the transmission, storage and modification of information [38]. Information dynamics is a recent framework characterising and measuring each of the primitives information-theoretically [49,41]. In viewing the state update dynamics of a random process as an information processing event, this framework performs an information regression in accounting for where the information to predict that state update can be found by an observer, first identifying predictive information from the past of the process as information storage, then predictive information from other sour...

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Emergence of collective changes in travel direction of starling flocks from individual birds' fluctuations

Cited by 70 publications

References 30 publications

Domino-like propagation of collective U-turns in fish schools

Domino-like propagation of collective U-turns in fish schools

Dancing disclinations in confined active nematics

Informative and misinformative interactions in a school of fish

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