Delving deep into unheard waters: new types of low frequency pulsed sounds described for the boto (Inia geoffrensis)”

Authors

de Melo, J.F.

Additional Authors

Amorim, T.O.S. & Andriolo, A.

Year

2021

Publisher

Springer

Volume & Issue

101

Pages

pages 429–437

Country / Region

Brazil

Document Type

Peer-reviewed journal article

Species

Amazon river dolphin

Science Keywords

Bioacoustics

Conservation Measure

Species knowledge and understanding

Abstract

The Amazon river dolphin, or boto (Inia geoffrensis), is an endangered species, distributed over an extensive area of the Amazon–Orinoco basin. Here, we analyzed the acoustic behavior of a previously unstudied population of botos at the Juami-Japurá Ecological Station, Amazonas. We categorized call types according to their visual and acoustical parameters. Random forest decision trees were used to assess the validity of our classification. Six types of narrowband pulsed sounds were found, of which four are being described for the first time for the species. The vocalizations analyzed had mean maximum frequency of 25.7 kHz and mean minimum frequency of 1.1 kHz. The narrowband pulsed sounds are complex and different from those emitted by most members of the family Delphinidae. Although the acoustic repertoire of botos is not completely understood in functional terms, these pulsed sounds may play an important role in the social structure of the animals.