Efeito da presença de formigas na eclosão de ovos de tracajá (Podocnemis unifilis) na Reserva de Desenvolvimento Sustentável Piagaçu-Purus

Abstract

Nest predation is an important factor for populations of turtles, and ants are among the main predators after the men. In the Piagaçu-Purus Sustainable Development Reserve was observed the decrease in the number of hatching of tracajá eggs, by predation of ants that established colonies in tracajá nests. Thus, investigate the process of relocation of ant nests and their interaction with tracajá eggs is important to develop a plan of management for the preservation of the species. Ants were collected in four rounds, the first and second rounds were carried out in the months September and December 2013 and the third and fourth in the same months of next year. Ants were sampled through established pitfalls in the nest and in an adjacent area (approximately 20m from the child). In total, 4,945 ants were collected in the tracajá nests and 2,396 ants were sampled in areas adjacent to the nests. S. geminata was the second most abundant species representing 45% of ants collected and was the only species that effectively preyed on tracajá nests. At the beginning of the incubation period, the abundance of S. geminata around the nests of P. unifilis and in the areas adjacent to the nest was similar (t = -0.379; p = 0.646). However, at the end of the incubation period the abundance of S. geminata around the nest was ~2 times larger than in the areas adjacent to the nests (t = 1.754; p = 0.046). Our results suggest that S. geminata is attracted to the tracajá nests during the hatching of the eggs. After hatching, tracajá chicks can spend up to 30 days inside the nest absorbing the remaining of the calf and becoming easy prey for the ants. After colonization by S. geminata all offspring in the nest are preyed upon. In this way, management actions at the end of the breeding season of P. unifilis, such as transfer eggs to safe places will likely be more efficient for the conservation of the species locally.