Introduction
Foraging mode, originally defined on the basis of clear differences in behaviors used to find and capture prey (MacArthur and Pianka, 1966; Pianka, 1966; Schoener, 1971) has become a central paradigm in lizard ecology (see, for example, Huey and Pianka, 1981; Vitt and Congdon, 1978; Cooper, 1994a, b, 1995a, b; Perry, 1999; Perry and Pianka, 1997; Perry et al., 1990). Sit-and-wait (often referred to as “ambush”) foragers pursue prey detected visually from short distances, often returning to the same perch after capturing a prey item. Wide (often referred to as “active”) foragers move through the environment in search of prey that are often hidden, using a combination of visual and chemical cues to locate and discriminate prey. Trade-offs between energy invested in capture versus search for these two foraging modes are key elements of optimal foraging theory (MacArthur and Pianka, 1966; Charnov, 1976; Kamil, 1983). Identification of this foraging dichotomy has stimulated lizard research in many areas, including ecology, behavior, life histories, and physiology, to mention a few.
The foraging mode paradigm is much more complex than previously envisioned, as evidenced by research presented in other chapters in this book. For example, what appeared to be a sharp historical separation of foraging modes (see, for example, Pianka and Vitt, 2003; Vitt et al., 2003) is replete with exceptions embedded in major clades, suggesting either loss of or multiple origins of traits often linked to foraging mode (see, for example, Cooper, 1997; Cooper et al., 1997).