Introduction

Active foraging and sit-and-wait predation are often considered as two very disparate foraging strategies (Huey and Pianka, 1981). As implied by the name, active foragers actively search for food and, in the process, will cover large distances. Typical sit-and-wait predators on the other hand will wait motionless for prey to pass by, at which they will dart with a sudden burst of movement. These animals are often cryptically colored and do not move around for prolonged periods of time (see Table 7.1). Herbivores, however, need to forage actively for food, but have radiated extensively within a group of lizards seemingly predisposed to a sit-and-wait strategy.

Differences in foraging mode in lizards seem to be roughly associated with a deep split within the lizard phylogeny: the transition from “fleshy-tongued” Iguania to the “scaly-tongued” Scleroglossa. It has been suggested that this split is tightly associated with evolution of the use of the tongue for chemoreceptive purposes either at the level of the scleroglossans (Schwenk, 1993, 2000; Cooper, 1994) or independently in each of the scleroglossan radiations (Reilly and McBrayer, this volume, Chapter 10). The development of a tongue that allowed animals to detect and assess sedentary prey is thought to have allowed lizards to search extensive areas for prey that would otherwise remain undetected. As a consequence, active foragers tend to consume unpredictably distributed and clumped prey (e.g. termites). Sit-and-wait predators, on the other hand, tend to eat more active and larger prey (Pough et al., 2001).