Using their acoustic repertoire by bottlenose dolphins ( Tursiops truncatus ) from the southern Gulf of Mexico (Veracruz and Campeche)

Bottlenose dolphins live along the coast of the southern part of the Gulf of Mexico using their acoustic repertoire to communicate and inspect their environment. We studied the acoustic repertoire of bottlenose dolphins that inhabit the waters off Alvarado, Veracruz, and in Laguna de Términos, Campeche, México, and how it may relate to the dolphins' general behavioral state and herd size. Results show that bottlenose dolphins produce by far more click trains than any other phonation in all behavioral states (feeding, social, rest, and travel), while whistling was abundant when herds had more individuals. Silence was found during all behavioral states, but very seldom in herds of large size. During feeding, more whistle types were produced but of low complexity; during travel, whistle types were the least complex; during social and rest, whistle types were of more complexity; and during rest, less whistles were produced. These results confirm that bottlenose dolphins are choosing when and where to produce their phonations. Therefore, more detailed studies are needed to understand how these animals are using their acoustic sense to communicate and inspect their environment. [Work supported by CONACyT, Gobierno Edo. de Campeche, PAPIIT-UNAM, SIREI-UV, and SGIAR-SMM.]