For a better understanding of the foraging behavior of Grey Heron in an intertidal area we developed predictive models of number of attempts/10′ using Poisson regression. The models were obtained considering the following four variables: age of bird, tidal hours, bi–monthly period, and substrate type, obtaining a total of 15 models. The most parsimonious model obtained using the Akaike Information Criteria included tidal hour, age of bird and substrate type as predictive variables. The mean

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... er of attempts/10′ was highest in the four hours around low tide and in water and muddy substrates, while foraging activity was scarcely recorded in sandy substrates. No differences of effectiveness were found between adult and juvenile birds. Grey Heron showed preference for very small and small prey, increasing handling time with prey length.