Dietary niche differentiation facilitates coexistence of two large carnivores

Abstract

AbstractAn animal's diet is an important attribute of its niche, and affects the role that it plays in the ecosystem. Comparing the diets of sympatric species reveals the level of dietary niche overlap between them, which can be used to gauge the potential for competition, as well as each species’ vulnerability to competitive exclusion. Because of a morphology adapted to predation, sympatric carnivores can have particularly aggressive and dangerous competitive interactions; the intensity of which may be directly related to the amount of overlap in prey species consumed. Using predator scat analysis and prey survey techniques, we analyze and compare the underlying mechanisms of prey selection – prey body size and group size – between sympatric populations of leopard Panthera pardus and lion Panthera leo, to test for possible means of competitive avoidance between them. Because leopard and lion differ in both size and social structure, we controlled for the differing prey handling ability of each species, and found that there was still a significant difference in mean prey body size preference between the two carnivores (P = 0.050), despite a relatively high level of dietary niche overlap (0.717). Both species avoid prey in larger groups, but the tendency is more pronounced for leopards. Where intraguild competitors overlap spatiotemporally, dietary niche segregation such as this may be a mechanism through which competition is avoided and, in the case of carnivores, could reduce the frequency of potentially costly interactions.