Optimal foraging strategies: Levy walks balance searching and patch exploitation under a very broad range of conditions

While evidence for optimal random search patterns, known as Levy walks, in empirical movement data is mounting for a growing list of taxa spanning motile cells to humans, there is still much debate concerning the theoretical generality of Levy walk optimisation. Here, using a new and robust simulation environment, we investigate in the most detailed study to date (24 x 10(6) simulations) the foraging and search efficiencies of 2-D Levy walks with a range of exponents, target resource distributions and several competing models. We find strong and comprehensive support for the predictions of the Levy flight foraging hypothesis and in particular for the optimality of inverse square distributions of move steplengths across a much broader range of resource densities and distributions than previously realised. Further support for the evolutionary advantage of Levy Walk movement patterns is provided by an investigation into the 'feast and famine' effect, with Levy foragers in heterogeneous environments experiencing fewer long 'famines' than other types of searchers. Therefore overall, optimal Levy foraging results in more predictable resources in unpredictable environments. (C) 2014 Elsevier Ltd. All rights reserved.