Document Type
Article - postprint
Department
Engineering (HMC), Mathematics (HMC)
Publication Date
2008
Abstract
We construct an individual-based kinematic model of rolling migratory locust swarms. The model incorporates social interactions, gravity, wind, and the effect of the impenetrable boundary formed by the ground. We study the model using numerical simulations and tools from statistical mechanics, namely the notion of H-stability. For a free-space swarm (no wind and gravity), as the number of locusts increases, the group approaches a crystalline lattice of fixed density if it is H-stable, and in contrast becomes ever denser if it is catastrophic. Numerical simulations suggest that whether or not a swarm rolls depends on the statistical mechanical properties of the corresponding free-space swarm. For a swarm that is H-stable in free space, gravity causes the group to land and form a crystalline lattice. Wind, in turn, smears the swarm out along the ground until all individuals are stationary. In contrast, for a swarm that is catastrophic in free space, gravity causes the group to land and form a bubble-like shape. In the presence of wind, the swarm migrates with a rolling motion similar to natural locust swarms. The rolling structure is similar to that observed by biologists, and includes a takeoff zone, a landing zone, and a stationary zone where grounded locusts can rest and feed.
Rights Information
© 2008 EDP Sciences, Springer-Verlag
Terms of Use & License Information
DOI
10.1140/epjst/e2008-00633-y
Recommended Citation
C. M. Topaz, A. J. Bernoff, S. Logan, and W. Toolson, "Aggregations, Interactions, and Boundaries: A Minimal Model for Rolling Swarms of Locusts," The European Physical Journal - Special Topics 157 (2008) 93-109. doi: 10.1140/epjst/e2008-00633-y
