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Open Access item Animal search strategies: a quantitative random walk analysis
da Luz, M. G. E.
Viswanathan, G. M.
|Keywords:||Foraging theory, Random search strategies, Lévy walks, Correlated random walks|
|Publisher:||Ecological Society of America|
|Citation:||Ecology 86(11) : 3078-3087 (2005)|
|Abstract:||Recent advances in spatial ecology have improved our understanding of the
role of large-scale animal movements. However, an unsolved problem concerns the inherent
stochasticity involved in many animal search displacements and its possible adaptive value.
When animals have no information about where targets (i.e., resource patches, mates, etc.)
are located, different random search strategies may provide different chances to find them.
Assuming random-walk models as a necessary tool to understand how animals face such
environmental uncertainty, we analyze the statistical differences between two random-walk
models commonly used to fit animal movement data, the Le´vy walks and the correlated
random walks, and we quantify their efficiencies (i.e., the number of targets found in relation
to total displacement) within a random search context. Correlated random-walk properties
(i.e., scale-finite correlations) may be interpreted as the by-product of locally scanning
mechanisms. Le´vy walks, instead, have fundamental properties (i.e., super-diffusivity and
scale invariance) that allow a higher efficiency in random search scenarios. Specific biological
mechanisms related to how animals punctuate their movement with sudden reorientations
in a random search would be sufficient to sustain Le´vy walk properties. Furthermore,
we investigate a new model (the Le´vy-modulated correlated random walk) that
combines the properties of correlated and Le´vy walks. This model shows that Le´vy walk
properties are robust to any behavioral mechanism providing short-range correlations in
the walk. We propose that some animals may have evolved the ability of performing Le´vy
walks as adaptive strategies in order to face search uncertainties.|
|Description:||10 páginas, 4 figuras.|
|Publisher version (URL):||http://www.esajournals.org/doi/pdf/10.1890/04-1806|
|Appears in Collections:||(CEAB) Artículos|
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