Diet and feeding behaviour of the leaf-litter frog Ischnocnema henselii (Anura: Brachycephalidae) in Araucaria rain forests on the Serra Geral of Rio Grande do Sul, Brazil†

†This article is dedicated to the memory of the late Marcos Di-Bernardo.

Abstract

We analysed the diet of Ischnocnema henselii from a subtropical Araucaria forest through stomach flushing. The identified prey items comprised arthropods such as spiders, ants, orthopterans, collembolans and homopterans. We consider I. henselii to be a nocturnal and opportunistic sit-and-wait predator. Small animals are preferred. Because this species lives permanently on the forest floor, we also determined the composition of the habitat's leaf-litter mesofauna. By using Winkler sieve extraction, we obtained a spectrum of small invertebrates that reflected the prey in the stomach contents well. The only exceptions were mites, the most abundant leaf-litter inhabitants, which frogs either avoided or ignored. Our results represent the first information on the diet of I. henselii and are discussed in comparison with data on related species and in relation to the relevance of this predator within the food web of subtropical montane rain forests in southern Brazil.

Keywords:

• Anura
• Ischnocnema henselii
• Araucaria forest
• stomach flushing
• southern Brazil

Acknowledgements

Our research was part of the FAPERGS/DLR-BMBF project “Araucaria forest” and was realized within the agreement between PUCRS and the University of Tübingen. We would like to thank T. Miranda and M. Ebner (LPB of the PUCRS) for help during field work, A. Kwet (State Museum of Natural History Stuttgart) for supporting our project and A. Angulo, S. Thomson and J. López for critical reading of previous versions of the manuscript. We thank Sabine Heinle (Brasilien-Zentrum Tübingen) for preparing the figures. We appreciate the facilities provided by the IMA staff of PUCRS. J.D. received a DAAD graduate student fellowship through the University of Tübingen.

Notes

†This article is dedicated to the memory of the late Marcos Di-Bernardo.