Analysis of whistles produced by the Tucuxi Dolphin Sotalia fluviatilis from Sepetiba Bay, Brazil.

Claudia Erber,Sheila M Simão

doi:10.1590/s0001-37652004000200029

Claudia Erber, Sheila M Simão

Open Access

https://doi.org/10.1590/s0001-37652004000200029

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Abstract

From July 2001 to June 2002, we recorded a total of 2 h 55 min of Tucuxi Dolphin Sotalia fluviatilis vocalizations from Sepetiba Bay, Brazil (22 degrees 35'S-44 degrees 03'W). A total of 3350 whistles were analyzed quantitative and qualitatively and were divided into 124 types, by visual inspection of sonograms. The following parameters were measured: Initial Frequency, Final Frequency, Minimum Frequency, Maximum Frequency, Duration, Number of Inflections, Frequency at the Inflection Points, Frequency at 1/2, 1/4, and 3/4 of whistle duration, Presence of Frequency Modulation and Harmonics. Ascending type whistles (N = 2719) were most common, representing 82% of the total. Dolphin behavior and average group size observed during recording influenced the whistle's quantitative and qualitative parameters. The results demonstrate the great diversity of whistles emitted and indicate a functional role of these vocalizations during the observed behaviors.

Highlights

The research presented here will characterize the whistles of the Tucuxi population from the Sepetiba Bay
Ascending type whistles (N=2719) were most common, representing 82% of the total, Descending type whistles (N=240) were 7%, Low Modulation Frequency type whistles (N=348) were 10%, and other types of whistles (N=8), together with Duet type whistles (N=35), represented 1% of the total
There were as many as 9 inflections in these whistles; and 142 whistles had 1 to 10 harmonics

Summary

Introduction

There have been extensive studies on the intraspecific sound communication of the different cetacean groups, but there are few reports about Tucuxi Dolphin Sotalia fluviatilis vocalizations (Caldwell and Caldwell 1970, Alcuri and Busnel 1989, Kamminga et al 1993, Ding et al 1995, Sauerland and Dehnhardt 1998, Figueiredo 2000, Monteiro-Filho and Monteiro 2001, Azevedo and Simão 2002), and about the association of sound and behaviors in natural environment (Ding 1993, Schultz and Corkeron 1994, Ding et al 1995).The sea ecotype of Sotalia fluviatilis is distributed in coastal waters, from Nicaragua to theSouth of Brazil (Carr and Bonde 2001), and produces whistles of frequencies from 1.6 to 23.9 kHz (Richardson et al 1995). There have been extensive studies on the intraspecific sound communication of the different cetacean groups, but there are few reports about Tucuxi Dolphin Sotalia fluviatilis vocalizations (Caldwell and Caldwell 1970, Alcuri and Busnel 1989, Kamminga et al 1993, Ding et al 1995, Sauerland and Dehnhardt 1998, Figueiredo 2000, Monteiro-Filho and Monteiro 2001, Azevedo and Simão 2002), and about the association of sound and behaviors in natural environment (Ding 1993, Schultz and Corkeron 1994, Ding et al 1995). In the Sepetiba Bay, there is a resident Tucuxi Dolphin population (Pereira 1999). They are seen in groups of 2 to 200 animals The research presented here will characterize the whistles of the Tucuxi population from the Sepetiba Bay

Methods

Results

Conclusion