Coexisting generalist scavengers occupy different feeding niches

Abstract

Generalist scavengers are perceived to exhibit broad feeding niches, and therefore, it is predicted that coexisting generalist scavengers should exhibit extensive food niche overlap. However, ecological theory suggests that no two species can coexist while using the same limited resources in the same manner because competitive differences between the species will result in one species being outcompeted. Thus, some differentiation of the diets of coexisting generalist scavengers must exist in order to avoid competitive exclusion. In this study, I analyzed the feeding niches of two species of coexisting generalist scavengers (hermit crabs; Clibanarius digueti and Paguristes perrieri) to determine whether the species overlap in their: (1) preferred food items and (2) past diets. Food choice experiments conducted in the field showed that the species’ preferences for the food items offered largely overlapped. However, gut content and stable isotope analyses of collected specimens revealed significant differences in the past diets of the species. These analyses suggest that C. digueti consumes more photosynthetic materials than P. perrieri. The results suggest that the species differentiate their diets despite both feeding opportunistically on carrion and detritus washed into the intertidal zone by the tides.