A solitary rough-toothed dolphin (Steno bredanensis) in a superport area on northern Rio de Janeiro State, SE Brazil

Ana Paula Madeira Di Beneditto,Salvatore Siciliano

doi:10.1590/10.1590/1676-0611-bn-2020-1028

Ana Paula Madeira Di Beneditto, Salvatore Siciliano

Open Access

https://doi.org/10.1590/10.1590/1676-0611-bn-2020-1028

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Abstract

Abstract: The solitary behavior is an unusual and peculiar behavior reported in a few sociable dolphin species. This study presents the solitary behavior of an adult rough-toothed dolphin, Steno bredanensis, in the Açu Superport (21º49’S; 041º00’W), northern Rio de Janeiro State, SE Brazil. Data about the dolphin were obtained from mobile phone videos and reports by local professionals. Probably, the same dolphin was there since 2017-2018 up to April 2020 (at least). In general, the solitary dolphin swims next to supply boats navigating along the port internal channel, and it rarely continues towards open sea. The dolphin plays with buoys and containment barriers, rubs itself against hulls, and bow-rides and jumps. There is no report of people swimming with this solitary dolphin, touching it, or offering it food in the Açu Superport. Thus, there seems to be no threats to the animal’s integrity locally.

Highlights

Solitary dolphins are social species living apart from their own groups, with little or even no contact with conspecifics, and a high tendency to socialize with humans in different levels, such as touching, social, sexual and playing behaviors (Wilke et al 2005). Wilke et al (2005) raised some reasons to explain why social dolphins become solitary and sociable towards people; but until now these reasons remain somewhat speculative. Nunny & Simmonds (2019) summarized the current knowledge regarding solitary delphinids and monodontids, detailing cases recorded since 2008 worldwide
This study presents the solitary behavior of a sociable rough-toothed dolphin in a port area on northern Rio de Janeiro State, Brazil
The interviewees answered the same questionnaire, with open questions about the routine in the Açu Superport, since when the solitary dolphin has been there, the dolphin’s behavior, and if they swim with the dolphin, touch it or offer food to it

Summary

Introduction

Solitary dolphins are social species living apart from their own groups, with little or even no contact with conspecifics, and a high tendency to socialize with humans in different levels, such as touching, social, sexual and playing behaviors (Wilke et al 2005). Wilke et al (2005) raised some reasons to explain why social dolphins become solitary and sociable towards people (e.g., food availability, loss of habitat, lack of connectivity between dolphin populations, predation risk, and dolphin’s personality); but until now these reasons remain somewhat speculative. Nunny & Simmonds (2019) summarized the current knowledge regarding solitary delphinids and monodontids (ten different species), detailing cases recorded since 2008 worldwide. The solitary behavior of the rough-toothed dolphin, Steno bredanensis (Lesson 1828), was reported from a juvenile male near a Brazilian Navy base in Sepetiba Bay (22o54’S-23o04’S), southern Rio de Janeiro State, SE Brazil (Flach & Dias 2020; Maciel et al 2020). This study presents the solitary behavior of a sociable rough-toothed dolphin in a port area on northern Rio de Janeiro State, Brazil.

Results

Conclusion