Optimal Diet as a Function of Absolute Abundance, Relative Abundance, and Relative Value of Available Prey

Abstract

A model is presented that specifies the optimal diet of a predator faced with a range of kinds of potential prey. The optimal diet is defined to be the set of kinds of prey which if eaten whenever encountered will maximize the intake of food value per unit time. The parameters required to determine the optimal diet are the absolute abundance of potential food, the relative values to the predator of potential prey types, and the relative abundances of the potential prey types. Predictions of the model are that no diet can be optimal if it excludes a prey type more valuable than any of the included prey types; number of prey types eaten by a predator which is feeding optimally for a fixed relative value and relative abundance of prey types decreases as the absolute abundance of all potential food increases; determination of optimal diet is not independent of the relative abundances of the possible prey; but a small change in relative value is more effective in changing the optimal diet than is a small change in relative abundances of the potential prey. Relative abundance of the potential food types is not very important in determining the optimal diet; relative value of prey types is quite important; but absolute abundance of food is the overriding parameter in the determination of optimal diet.