Optimal Foraging: Field Tests of Diet Choice and Habitat Switching

Abstract

Synopsis. The application of optimal foraging theory to questions of predator behavior, and evidence bearing on the utility of this construct, are reviewed. Experimental tests of simple models predicting prey choice are examined with particular reference to the sizeselection of prey by fish. Laboratory estimates of model parameters are then used to predict prey choice in the field and data from several field tests are presented which corroborate these predictions. When parameters are habitat specific this permits predic? tions of net return from foraging in different habitats and consequendy predictions of habitat use and switching. Field data gathered to test these predictions demonstrate that fish feed in the richer habitats and switch habitats when the profitability of one drops below that of another. Examples are provided showing how these models can then be used to relate behavioral and morphological differences between species and questions at higher levels such as the nature of species interactions and community structure. It is suggested that this may be one of the more useful applications of optimal foraging theory. Finally, some of the criticisms of the theory and important questions requiring further study are discussed.