Morphology, performance, and foraging mode

Introduction, The feeding behavior of an animal is a fundamental attribute that has major fitness implications. Individual variation in the success with which prey is acquired ultimately affects growth rate, survivorship and reproductive success. Foraging success is linked to search behavior, which profoundly influences the variety and number of prey encountered (Pianka, 1966, 1973; Pietruszka, 1986). The ability to find prey therefore affects food intake and ultimately an individual's energy budget. The importance of foraging success is manifest in the myriad of behaviors animals display for the searching, pursuit, and capture of prey. Different modes of search behavior also entail costs. The duration of time spent foraging and the type of habitat an animal searches for food affects the risk of predation and ability to avoid predators (Huey and Pianka, 1981). Not surprisingly, the analysis of foraging behavior has been an important topic in ecology and evolutionary biology (Schoener, 1971; Gerritsen and Strickler, 1977; Stephens and Krebs, 1986; Perry and Pianka, 1997). Past investigations proposed a dichotomy in foraging patterns based on observations of consistent and prominent differences in behaviors among species in how prey are pursued and captured (see McLaughlin, 1989; Vitt and Pianka, this volume, Chapter 5; Perry, this volume, Chapter 1). Most species have been classified as either “ambush” (“sit-and-wait”) predators or widely (active) foraging predators (Pianka, 1966; Regal, 1978; Huey and Pianka, 1981) based on qualitative examination of activity patterns in the field.