Christian Yates - United by noise: Randomness helps swarms stay together

Amongst the most striking aspects of the movement of many animal groups are their sudden coherent changes in direction. Recent observations of locusts and starlings have shown that this directional switching is an intrinsic property of their motion. Similar direction switches are seen in self-propelled particle and other models of group motion. Comprehending the factors which determine such switches is key to understanding the movement of these groups.

In this talk I will explain how it is possible to replicate qualitatively the locusts' behaviour using self-propelled particle models. I will assume that the mean velocity of the self propelled particles can be modelled by a simple stochastic differential equation (SDE). One can then apply the 'equation-free technique' to find the coefficients of such an assumed SDE. Using the same technique one can also find the coefficients of a similar SDE for actual locust data. This systematic approach makes it possible to identify key differences between the self-propelled particle model and the data, revealing that individual locusts increase the randomness of their movements in response to a loss of alignment by the group. I will thus describe qualitatively how I believe locusts use noise to maintain swarm alignment.

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A copy of his talk is available here.
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