Search Modes of Birds and Lizards: Evidence for Alternative Movement Patterns

Abstract

Many studies classify predators as either sit-and-wait foragers or active searchers and contend that these two search strategies correlate with syndromes of behavioral, physiological, and morphological traits (the syndrome hypothesis). I use move-frequency data (moves per minute) for 58 species of forest birds and 22 species of lizards to study whether the move-frequency distributions of these two predator types are bimodal. A statistical test designed to distinguish bimodal from unimodal distributions indicates bimodal distributions of move frequencies for both taxa. Further, observed cumulative distributions of move frequencies are not significantly different from predicted, bimodal distributions. Conversely, normal, lognormal, and uniform distributions provide inadequate descriptions of move frequencies. The same conclusions are reached when Australian and North American birds are considered separately. Hence, for birds and lizards, the dichotomous view of predator search strategies is realistic; h...