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Environmental context explains Lévy and Brownian movement patterns of marine predators

journal contribution
posted on 2010-01-01, 00:00 authored by N Humphries, N Queiroz, J Dyer, N Pade, M Musyl, K Schaefer, D Fuller, J Brunnschweiler, T Doyle, J Houghton, Graeme HaysGraeme Hays, C Jones, L Noble, V Wearmouth, E Southall, D Sims
An optimal search theory, the so-called Lévy-flight foraging hypothesis1, predicts that predators should adopt search strategies known as Lévy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey2, 3, 4. Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Lévy behaviour has recently been questioned5, 6. Consequently, whether foragers exhibit Lévy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory’s central predictions. Here we use maximum-likelihood methods to test for Lévy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Lévy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Lévy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Lévy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Lévy-flight foraging hypothesis1, 7, supporting the contention8, 9 that organism search strategies naturally evolved in such a way that they exploit optimal Lévy patterns.

History

Journal

Nature

Volume

465

Issue

7301

Pagination

1066 - 1069

Publisher

Nature Publishing Group

Location

London, England

ISSN

0028-0836

eISSN

1476-4687

Language

eng

Publication classification

C4.1 Letter or note

Copyright notice

2010, Nature Publishing Group