The newly described Araguaian river dolphins, Inia araguaiaensis (Cetartiodactyla, Iniidae), produce a diverse repertoire of acoustic signals

• Published in: PeerJ (San Francisco, CA) Vol. 7; p. e6670
• Main Authors: Melo-Santos, Gabriel, Figueiredo Rodrigues, Angélica Lúcia, Tardin, Rodrigo Hipólito, de Sá Maciel, Israel, Marmontel, Miriam, Da Silva, Maria Luisa, May-Collado, Laura Johanna
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 19.04.2019; PeerJ, Inc; PeerJ Inc
• Subjects: Acoustic communication; Acoustics; Analysis; Animal Behavior; Artificial neural networks; Behavior; Biodiversity; Biology; Boto; Communication; Concerts; Dolphins & porpoises; Ecology; Evolution (Biology); Freshwater Biology; Inia araguaiaensis; Iniidae; Laboratories; Marine mammals; Mother-calf pairs; Neural networks; Non-linear phenomena; Rivers; Studies; Zoology; Brazil; Rio de Janeiro Brazil; Acoustic communication; Behavior; Mother-calf pairs; Non-linear phenomena; Boto
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.6670

The recent discovery of the Araguaian river dolphin ( ) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour. We analysed frequency contours of 727 signals (sampled at 10 ms temporal resolution). These contours were analyzed using an adaptive resonance theory neural network combined with dynamic time-warping (ARTwarp). Using a critical similarity value of 96%, frequency contours were categorized into 237 sound-types. The most common types were emitted when calves were present suggesting a key role in mother-calf communication. Our findings show that the acoustic repertoire of river dolphins is far from simple. Furthermore, the calls described here are similar in acoustic structure to those produced by social delphinids, such as orcas and pilot whales. Uncovering the context in which these signals are produced may help understand the social structure of this species and contribute to our understanding of the evolution of acoustic communication in whales.