Partial prey consumption by ambush predators

Abstract

Published models of partial prey consumption fall into two basic categories: optimal foraging models and mechanistic models. All optimal foraging models have utilized a form of the Marginal Value Theorem to generate predictions about prey consumption behaviour; in this approach, prey are considered to be analogous to patches with decreasing marginal utility. Laboratory studies of prey consumption behaviour have shown limited qualitative agreement with predictions from these models. Several mechanistic models have been proposed as alternatives to the Marginal Value Theorem to account for these observed discrepancies. Here we show that the Marginal Value Theorem is inappropriate for ambush predators, although a majority of studies have used ambush predators to test optimality models of partial prey consumption. Therefore, we derive models explicitly designed to generate predictions of partial prey consumption by ambush predators, and review the conclusions of previous work in light of these models. Lack of fit between predictions and observations are shown to be attributable to the improper use of the Marginal Value Theorem.