Introduction

To reproduce successfully, an organism must survive, attain suitable size, attract a mate, and produce viable offspring. All of these activities require that the individual obtain considerable amounts of energy. Foraging success can thus strongly impact reproductive success (Travers and Sih, 1991; Bernardo, 1994; Nilsson, 1994). Reproductive success is the fabric upon which natural selection works (Darwin, 1859). Evolutionary biologists and behavioral ecologists, starting with the pioneering work of MacArthur and Pianka (1966) and Emlen (1966), have therefore shown considerable interest in foraging behaviors and their correlates. The resulting literature is voluminous and often contentious: too much so for a single chapter, or even volume, to effectively summarize. In keeping with the theme of this book, I focus on the issue of bimodality in lizard foraging behavior, its phylogenetic background, and its putative correlates.

Before one can discuss patterns, however, methodological issues must be clarified. This chapter is therefore divided into two main sections. The first section focuses on some previously neglected methodological issues related to measurement of foraging behavior. Establishing these is crucial for ensuring data quality in the analyses that follow. The second section then concentrates on testing theoretical predictions of foraging theory, and on some conceptual consequences of what has been learned to date. Because the literature is so extensive, I frequently limit the use of references to representative examples throughout this chapter.