Tuesday, August 19, 2014

[Herpetology • 2014] Sound Communication and Social Behavior in an Amazonian River Turtle Podocnemis expansa

 adult Giant South American river turtle Podocnemis expansa.
The turtle is the largest member of the side-necked turtle family and grows up to nearly 3 feet in length.
photo: C. Ferrara/Wildlife Conservation Society

The social behavior of turtles during the nesting season can be attributed to a series of functions such as reducing predation, increasing hatchling survivorship, and information exchange between nesting females. However, the mechanism(s) used to remain in a group during the different phases of nesting behavior has yet to be explained. The objective of this study is to document the sounds produced by Giant South American River Turtle, Podocnemis expansa, during the nesting period, and identify how acoustic mechanisms might facilitate social behavior and group aggregation during this period. From September 2009 to October 2011, the sound repertoire of P. expansa was identified during the nesting period, which begins with the migration of the turtles from the flooded forests to the nesting beaches and terminates when the hatchlings emerge and the females migrate with the hatchlings to the flooded forests. Sounds were recorded when the turtles were active in different behavioral patterns (1) migrating; (2) aggregating in front of the nesting beaches before basking; (3) nesting at night; (4) waiting in the water without nesting or after they have nested; and (5) waiting for the arrival of the hatchlings. We observed six types of sound in the recordings of turtles made during the nesting period. These data indicate that this species is social, and that sound plays an important role in the synchronization of the activities of groups during the nesting season.

Keywords: Giant South American River Turtle, Migration, Nesting, Underwater vocalizations

Camila Rudge Ferrara, Richard C. Vogt, Renata S. Sousa-Lima, Bruno M.R. Tardio and Virginia Campos Diniz Bernardes. 2014. Sound Communication and Social Behavior in an Amazonian River Turtle (Podocnemis expansa). Herpetologica. 70(2):149- 156.
DOI: 10.1655/HERPETOLOGICA-D-13-00050R2

Scientists study 'talking' turtles in Brazilian Amazon
 Turtles are well known for their longevity and protective shells, but it turns out these reptiles use sound to stick together and care for young. Scientists working in the Brazilian Amazon have found that Giant South American river turtles actually use several different kinds of vocal communication to coordinate their social behaviors, including one used by female turtles to call to their newly hatched offspring in what is the first instance of recorded parental care in turtles.