Nonlinearities in the vocalizations of Stenella species in the Southwest Atlantic Ocean

Abstract

Some complex features found in tonal emissions may be the result of nonlinear phenomena in sound production systems, which may result in individually acoustic signals highly variable and complex. From the analysis of five opportunistic acoustic records of distinct groups, two of spinner (Stenella longirostris) and three of Atlantic spotted dolphins (Stenella frontalis), we registered the emission of six different types of nonlinearities. Spinner dolphins had less events presenting mostly biphonation in the form of nonparallel bands and subharmonics. Atlantic spotted dolphins presented a higher rate of these features presenting mostly biphonation and screams on their vocalizations. Although the exact function of these processes is still being investigated, recent documentation in several species suggests that they may play a communicative role. Describing the occurrence of these characteristics can indicate their level of importance, as well as its structure may be indicative of its function. This is the first record of these events in Stenella species in the Southwest Atlantic Ocean. Future studies that allow to associate the behavior of these species while emitting these signals would greatly increase the understanding of these events. This study was funded by Chevron.