Evaluation of predation in Podocnemis expansa and Podocnemis unifilis (Testudines, Podocnemididae) in the Javaés River, Tocantins

Abstract

Podocnemis expansa and P. unifilis long lived with late sexual maturation, which influences a low replacement rate of individuals. Their populations are characterized by low adults mortality, but high mortality of embryos and hatchlings. The natural nest predation is an important factor for hatchling success. In Javaés River, the eggs and hatchlings can be predated by a large number of animals such as birds, vultures (Coragyps atratus and Cathartes aura), carcará (Polyborus plancus), jabiru (Jabiru mycteria); lizards (Tupinambis teguixin) and small mammals, coati (Nasua nasua) and crab-eating-fox (Cerdocyon thous). About 65,98% of nests of P. unifilis are predated (41,68% totally and 24,30% partially). Only 5,31% of P. expansa nests are partially predated. There are many aquatic predators, like carnivorous fish, mainly piranhas (Serrasalmus nattereri) and caimans (Melanosuchus niger e Caimam crocodilus). The predators of P. unifilis females are: black caiman (Melanosuchus niger), jaguar (Panthera onca) and puma (Puma concolor), and of P. expansa females is the P. onca. In average 3,93% of P. unifilis females are predated annually while that to P. expansa the average is 5,66%.