Dear MARMAM Community,

My co-authors and I are happy to announce our recent open-access publication in the Journal of the Acoustical Society of America. In this paper, we analyse the stability and variability of signature whistles of wild free-swimming Indo-Pacific bottlenose dolphins (Tursiops aduncus). Please see the details and abstract below. The publication is available here: https://doi.org/10.1121/10.0036433

Ekaterina Ovsyanikova, Barry McGovern, Elizabeth Hawkins, Léonie Huijser, Rebecca Dunlop, Michael Noad; Balance between stability and variability in bottlenose dolphin signature whistles offers potential for additional information. J. Acoust. Soc. Am. 1 April 2025; 157 (4): 2982–2993. https://doi.org/10.1121/10.0036433

Abstract:

Bottlenose dolphins produce individually distinctive signature whistles (SWs) to broadcast identity. Stability of the SW frequency contour is essential to preserve identity information; however, SWs could carry additional information which requires variability. We used acoustic recordings from provisioned free-swimming Indo-Pacific bottlenose dolphins at Moreton Island (Mulgumpin), Australia, collected in 2002 and 2017–2018, to assess the long-term (15-year) stability in SWs, and if variability of acoustic parameters increases with whistle complexity. Stability was assessed by analyzing basic contour parameters (minimum and maximum frequency, duration, etc.) and visually. We quantified SW variability using two developed variability metrics. Complexity was defined using four developed metrics, and its effect on variability was tested. Our results demonstrated that SW contours remain highly stable over time, but minimum frequency decreased by 8.8%. SWs also showed different degrees of variability between individuals. Variability appeared to be higher in males than in females, possibly indicating differences in SW use in different social contexts. Furthermore, SWs with a greater level of frequency modulation varied more than less modulated whistles. We propose that SWs possess sufficient variation in their frequency contour to contain additional information, possibly related to social and behavioral context, while still maintaining their identity function.

Kind regards,

Ekaterina Ovsyanikova