Trophic niche of four sympatric direct-developing frogs (Anura: Strabomantidae) from Eastern Brazilian Amazonia

Abstract

Knowledge on the ecology of many Amazonian anuran species is still incipient, especially when it comes to resource partitioning. Here, we studied dietary variation of four Pristimantis species (P. chiastonotus, P. crepitaculus, P. gutturalis and P. zeuctotylus) from Eastern Brazilian Amazonia during the rainy and dry seasons. From 226 stomach contents retrieved through stomach-flushing, we observed that the four sympatric species can explore the generalist, sit-and-wait, and opportunistic foraging strategies, feeding mainly on highly mobile arthropods such as Diptera, Coleoptera, Hymenoptera, Hemiptera and Orthoptera, which were the most important prey categories. We found significant differences among the species for the volumetric composition of prey, and the amount of prey consumed was the main predictor for this condition in most species. The type of microhabitat was also a predictor for feed volumetric composition in some species. We report a higher perching height for P. chiastonotus, and lower perching in P. gutturalis; the first species had a wider dietary spectrum. These findings contribute to the understanding of resource partitioning among sympatric and closely related species.