Optimal Foraging Theory

Optimal foraging theory is the branch of behavioral ecology that seeks to understand how natural selection has shaped foraging behavior. The general strategy adopted is to build models of how animals should forage given various assumptions about the system, and then compare the predictions of these models with the behavior of real animals.

Classical optimal foraging models involve three kinds of assumptions: (1) those regarding the foraging decision being analyzed, (2) those regarding the currency the forager is maximizing, and (3) those regarding the constraints operating on the system (Stephens and Krebs, 1986).

In many classical optimal foraging models the currency that foraging animals are assumed to be maximizing is their long-term net rate of energy intake (Stephens and Krebs, 1986), where long-term rate is defined as the net energy intake divided by the total time spent acquiring this energy. Rate is a proximate currency that is assumed to relate closely to Darwinian fitness if it is maximized over the lifetime of the forager, because an animal that maximizes its rate of energy intake will achieve the greatest amount of energy for use in maintenance, growth, and reproduction in the least possible time, and time not spent foraging is time available for other fitness-promoting activities, such as looking out for predators and reproduction. Given that the computation of rate involves forming an estimate of the time spent foraging, interval timing is likely to be involved in many foraging decisions.

In the following sections I shall consider various foraging problems in which the ability to time intervals is potentially crucial to arriving at the optimal solution. In each case I will describe the problem faced by the forager, outline the solution to the problem that maximizes the rate of energy intake, and describe examples in which the behavior of animals has been shown to approximate the optimal foraging solution.

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