First acoustic evidence of signature whistle production by spinner dolphins (Stenella longirostris)

Abstract

Signature whistle (SW) is a distinctive acoustic signal, issued in a bout pattern of unique frequency modulation contour; it allows individuals belonging to a given group to recognize each other and, consequently, to maintain contact and cohesion. The current study is the rst scienti c evidence that spinner dolphins (Stenella longirostris) produce SWs. Acoustic data were recorded at a shallow rest bay called "Biboca", in Fernando de Noronha Archipelago, Brazil. In total, 1,902 whistles were analyzed; 37.85% (720/1,902) of them were classi ed as stereotyped whistles (STW). Based on the SIGID method, 60.97% (439/720) of all STWs were identi ed as SWs; subsequently, they were categorized into one of 18 SW types. SWs accounted for 23.08% (439/1,902) of the acoustic repertoire.External observers have shown perfect agreement at the time to classify whistles into the adopted SW categorization.Most acoustic and temporal variables measured for SWs showed mean values similar to those recorded in other studies with spinner dolphins, whose authors did not differentiate SWs from non-SWs. Principal component analysis has explained 77.79% of total SW variance, and it emphasized the relevance of shape/contour and frequency variables to SW variance. This scienti c discovery helps improving bioacoustics knowledge about the investigated species. Future studies should focus on continuous investigations about SW development and use by Stenella longirostris to help expanding individuals' identi cation (Photo ID and SW Noronha Catalog), assessing long-term stability and emission rates, and making mother-offspring comparisons (sex-based differences).

First identification of stereotyped whistle contour types by Pseudorca crassidens

“…However, information about SW derives mostly, from the common bottlenose dolphins ( Tursiops truncatus ; Bruck et al, 2022; Caldwell & Caldwell, 1965; Caldwell et al, 1990; Gridley et al, 2014; Janik & Sayigh, 2013; Rio et al, 2022). In addition to bottlenose dolphins, individually distinctive SW have been identified and described for eight other delphinid species (Rio, 2023a), namely: Indo‐Pacific bottlenose dolphins ( Tursiops aduncus ; Gridley et al, 2014), spinner dolphins ( Stenella longirostris ; Rio, 2023a), common dolphins ( Delphinus delphis ; Caldwell & Caldwell, 1968; Fearey et al, 2019), Atlantic spotted dolphins ( Stenella frontalis ; Caldwell & Caldwell, 1970), Pacific white‐sided dolphins ( Sagmatias obliquidens ; Caldwell et al, 1973), Atlantic white‐sided dolphins (Lagenorhynchus acutus ; Cones et al, 2023), Pacific humpback dolphins ( Sousa chinensis ; van Parijs & Corkeron, 2001), and Guiana dolphins ( Sotalia guianensis ; de Figueiredo & Simão, 2009).…”

Comparison of common bottlenose dolphin whistles in tropical waters

“…Quick & Janik, 2008;May-Collado & Wartzok, 2008). For example, personalized acoustic signals, called signature whistles (SWs; Rio, 2023;Rio et al, 2022) express identity information. When they are not taken into consideration (to avoid overestimation of the most repeated whistle structure), they can influence geographic comparisons since they are emitted as repetitive patterns and represent nearly 50% of coastal and ocean bottlenose dolphin whistles produced by free-ranging animals in the wild (Rio et al, 2022).…”