Attack-based indices, not movement patterns, reveal intraspecific variation in foraging behavior

摘要

In lizards, much of the research on foraging patterns has regarded foraging behavior as static within species and has quantified foraging based on movement patterns alone. Sole use of movement patterns has been recognized as problematic because movements are often related to activities other than foraging (e.g., reproduction). Consequently, intraspecific variation in foraging behavior and its ecological consequences (e.g., diet variation) have been dramatically under studied. In this study, we examined the foraging behavior and diet of the Florida scrub lizard (Sceloporus woodi). Our objectives were 1) to quantify the variation in foraging behavior through the activity season to document how movement and foraging varies between sexes across the breeding and post-breeding seasons, 2) to quantify the efficacy of movement patterns versus attack-based metrics in detecting variation, and 3) to quantify the dietary consequences of variation in foraging. We found no differences in movement patterns between seasons or sexes, but we did find sexual variation in attack behavior and corresponding seasonal and sexual variation in diet. Indeed, a new attack-based index, attacks while stationary (AWS), was able to show precisely how foraging patterns varied. Combining attack-based indices and lag sequential analysis provided a complete description of how prey was acquired compared with using movement patterns alone. Our results provide a cautionary note for future researchers; focusing solely on movement patterns and/or ignoring seasonal and sexual variation in foraging behavior misses ecologically relevant variation that is highly informative about the causes and consequences of changes in foraging behavior.