Predação de anuros nativos pela rã-touro (Rana catesbeiana: Ranidae) no sul do Brasil

Abstract

Bullfrogs (Rana catesbeiana) have been introduced in many continents causing impact on native species. We have studied the influence of bullfrogs on the native anuran fauna through the diet analysis of 291 specimens, collected between May 2002 and June 2003, in an area in the South of Brazil. In order to check the feeding importance of the food items, the Pinkas index was used, classifying them by their relative importance (IRI). To analyze ontogenetic changes in the diet, we compared the variation among weigh classes. The most important item found in the bullfrog diet was the anuran (IRI=2157.71) from the Leptodactylidae, Hylidae, Microhylidae and Ranidae families, totalizing nine preyed species. Anurans were found in all weight classes. These results show a potentially strong predation pressure on the native anuran fauna. A control program for this invasive species in natural environments in the South of Brazil is suggested to be undertaken urgently.