Comunicação acústica de tartaruga-da-amazônia (Podocnemis expansa (Schweigger, 1812), Testudines: Podocnemididae) na Reserva Biológica do Rio Trombetas, Pará, Brasil

Abstract

Turtles have been used in the diet of people in Brazilian Amazon since the colonization by the Portuguese. Even though a lot has been published on the conservation and management of these species, the scientific research concerning them is still lacking in some aspects due to the turbidity of the Amazonian rivers. Considering this, bioacoustics is an important aspect of the behavior of natural populations of turtles which needs to be studied. Characteristics of the sounds produced by turtles and the morphology of the inner ear are unknown. These are important aspects which need to be studied to understand interactions of the species in this group and the relationships that are established among individuals and their environment. For these reasons, the aims of this study are to document the sound repertoire of Podocnemis expansa during the nesting period, to observe the ontogeny of the sound pattern during the first year of life of this species, and to characterize the morphology of the inner ear of this species. P. expansa were recorded for 420 h in nature and in captivity, including adults, subadults, and hatchlings; 2253 sounds were documented. Based on the aural and spectral characteristics of these sounds, 11 types of sounds were classified. These sounds occurred in four different contexts: water, surface, nest, and egg. Both hatchlings and adults were found to have a greater diversity of sounds compared to subadults; the peak frequency of hatchlings was higher than that of the adults and subadults. During nesting, sounds produced by the adults had a peak frequency higher than the sounds produced in other behavioral contexts. Using radio telemetry with adults and hatchlings and sound record with adults and hatchlings as well, it was possible to indicates a distinct possibility of a strong social post hatching interaction between females and hatchlings. Twenty heads of P. expansa hatchlings were decalcified for anatomical analysis and sectioned for histological descriptions of the middle and inner ear structures. It was noted that some of the inner ear structures of these hatchlings are still in process of ossification. The results of this thesis, indicates that P. expansa has a complex vocal repertoir used by adults, subadults, and hatchlings, both in and out of the water, and that the inner ear upon hatching follows the same anatomical and histological pattern observed among other reptiles.