Dietary variation and overlap in D’Orbigny’s slider turtles Trachemys dorbigni (Duméril and Bibron 1835) (Testudines: Emydidae)

Abstract

Although D’Orbigny’s slider (Trachemys dorbigni) is the most abundant freshwater chelonian species in southern Brazil, little is known about its feeding habits. Our goal was therefore to evaluate this species’ dietary composition and niche variation there. For this, we collected road-killed animals (n = 73) on a federal highway (BR 392) between 2002 and 2003, and analysed their gut contents. We identified 26 different dietary items, and our results indicated that D’Orbigny’s slider is omnivorous in this area. Total food volume, as well as the degree of herbivory and carnivory, were similar between males and females. However dietary composition of plants was different: although both males and females fed on underwater plant matter, only females consumed surface macrophytes. This finding suggested differential microhabitat usage between males and females throughout the swamps.

Keywords:

• chelonian
• testudines
• emydidae
• herbivory
• carnivory

Acknowledgements

We would like to thank the team of the UFRGS Herpetology laboratory, especially Dr Laura Verrastro and Martin Schoesler MSc. We thank Paulo Eduardo A. Bergonci for help in the field and with data analyses, as well as Daniel da Borba Rocha MSc for assistance and exchange of knowledge. We are grateful to Dr Bruno Irgand for macrophyte identification and to Eugenia Naro-Maciel for revision of the English. The research was carried out under an award from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).