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Charlas y Presentaciones

Following the line: Marine birds fly on top of ocean coherent structures

By E. Hernandez-Garcia, with C. Lopez and colaborators
Invited talk at the International Workshop on 'Search and stochastic phenomena in physical and biological systems". Palma de Mallorca 2012

Statistical properties of animal displacements have been usually interpreted as consequences of purely random process or of efficient search strategies. Here we point out the importance of environmental heterogeneity by showing, from combined oceanographic and ecological datasets on the Mozambique channel, that frigatebirds fly on top of ocean structures known as Lagrangian Coherent Structures. These are the edges of ocean eddies or, more generally, stable or unstable manifolds of hyperbolic locations in the sea surface flow. These structures are located from a finite-size Lyapunov exponent analysis of sea surface velocities, as measured by satellite altimetry. Our findings imply that the strong intermittency of the physical medium in which the birds and their prey live strongly constrains animal behavior, with implications on optimality of search processes.