Six species of Amazonian Woodcreepers (Aves: Dendrocolaptidae) preying upon lizards and frogs

Abstract

Dietary data from a large sample of woodcreepers (16 spp., n = 139), revealed that six species of dendrocolaptids occasionally feed upon lizards and frogs. These birds, which are mainly insectivorous, encounter and feed on lizards while perching on tree trunks, probably in association with army-ant swarm feeding behaviour. Frog intake may be related to declines in the abundance of invertebrate prey. The bones recovered were identified as one small species of gecko, Gonatodes humeralis, and at least one anuran. We estimate that in the entire sample, about eight lizards and two frogs were ingested. The partially digested gecko material allows determination of which bones are more resistant to digestion, although it is possible that these elements were differentially retained in the stomach. These elements correspond to the more frequently preserved bones in the fossil record of geckos, indicating that the same portions of the skeleton persist under the processes of both digestion and fossilization.

Keywords:

• insectivorous birds
• lizard
• frog
• stomach contents
• Amazon Basin

Acknowledgements

We thank R. Montero, L. Allcock, and an anonymous reviewer for their comments that improved this manuscript. L. Ponssa (Instituto de Herpetología, FML) for her help identifying the frog bones. We also thank the following curators for access to material under their care: R. Thomas (personal collection) K. de Queiroz (USNM), D. Frost and D. Kizirian (AMNH), C. McCarthy (NHMUK), K. Kozak (JFBM), L.F. Silveira (MZUSP), M. Raposo (MNRJ), and A. Aleixo (MPEG). S. Raredon and K. Tighe (USNM) kindly assisted us obtaining the X-rays. JDD and AMB were supported by the Lemole Endowed Chair funds and National Science Foundation grant DEB 0844523. VK was benefited from research fellowship from Capes. GRRB was supported by Capes/Faperj PAPD post-doctoral fellowship, and E.H. from CNPq grant.