Descriptive parameters of pulsed calls for the spinner dolphin,Stenella longirostris, in the Fernando de Noronha Archipelago, Brazil

Abstract

The aim of this work is to describe the repertoire of calls utilized by the spinner dolphins (Stenella longirostris) in the southern Atlantic Ocean. We measured four acoustic parameters of the fundamental frequency of each call: (i) duration; (ii) frequency amplitude; (iii) minimum frequency; and (iv) maximum frequency. We also classified calls by their shape contour by visual inspection of the spectrograms. The obtained values for call duration were 0.046 to 2.08 seconds (mean 0.433, standard deviation (SD) 0.433), amplitude of 0.13 to 2.01 kHz (mean of 0.36, SD 0.29), minimum frequency of 0.22 to 1.80 (mean 0.55, SD 0.29), maximum frequency of 0.46 to 7.50 (mean 1.00, SD 0.89). We classified 73 calls by spectral contour, identifying six basic types of discernible calls, showing heterogeneity among the call types, with C1, C2 and C3 calls presenting higher frequencies, 21, 30 and 23%, respectively. We found that the calls of S. longirostris in the Fernando de Noronha Archipelago are more diverse and complex than previously recognized for spinner dolphins and further studies worldwide can reinforce the broad use of this sound for the species repertoire.

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

“…There are no published sound recordings from Australia. Their sounds have instead been document from Hawaii [230,[256][257][258][259][260][261][262], the Eastern Tropical Pacific [151,152], the northwestern Atlantic [174], Brazil [263][264][265] and the western Indian Ocean off Madagascar [266].…”