Dieta de quatro espécies do gênero Podocnemis (Testudines, Podocnemididae) na Reserva de Desenvolvimento Sustentável Uatumã, Amazonas, Brasil

Abstract

Knowledge of diet helps in better understanding the evolution of animal groups and their interactions with the environment in which they live. For turtles some factors directly influence the supply: sex, habitat, body size, competition and availability of food items. The knowledge of the food habits of coexisting species is important to understand whether similar diets result in interaction, which in some cases can have negative consequences for some species. Among all freshwater turtles of Amazonia, Podocnemis spp. historically are the most threatened by the use as a protein source; knowledge of their ecology is an important tool for conservation. The objective this study is to compare the diets of Podocnemis erythrocephala, Podocnemis expansa, Podocnemis sextuberculata and Podocnemis unifilis in Uatumã Sustainable Development Reserve, Amazonas and relate the quantitative and qualitative variations of food resources used by species, sex and body size of the animals, as well as the place and time of capture. For this goal, stomach contents were collected from animals in three lakes of the study area in four seasons. I also wanted to examine the effect of body size on food items consumed and test for indices of feeding niche overlap among the species studied. Podocnemis sextuberculata consumed the least amount of food and Podocnemis expansa used for largest number of food items. Four species are primarily herbivorous and their diets were composed mainly of fruits and seeds (85.4% mean percentage by volume). Genipa americana (Rubiaceae) was most important in the diet of all species, except in Podocnemis sextuberculata. Size did not influence the qualitative or quantitative variation of food items, except in Podocnemis erythrocephala (r ² = 0.427, p = 0.029), which showed a linear relationship between carapace length and volume of the stomach contents. The highest food niche overlap was obtained between P. expansa and P. unifilis (Øjk = 0,852) and the lowest between P. erythrocephala and P. sextuberculata (Øjk = 0,453). The turtles tend to partition the food resources more in areas which had more species feeding than in areas with fewer species feeding.