Non-linear phenomena: a common acoustic feature of bottlenose dolphin (<i>Tursiops truncatus</i>) signature whistles

Sportelli, Jessica J.; Jones, Brittany L.; Ridgway, Sam H.

doi:10.1080/09524622.2022.2106306

Cited by 7 publications

(4 citation statements)

References 69 publications

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“…Most whistles were preceded by short click trains or burst-pulse sounds and featured numerous steps and breaks (Lima et al, 2012;Lima et al, 2016). The regular occurrence of this click train immediately prior to its signature whistle suggests that it may be a component of the dolphin's signature whistle (Sportelli et al, 2023). Future studies will need to ascertain whether this is a typical feature of rough-toothed dolphin signature whistles, more prominent in dolphins that are unwell, or if it is a feature individually unique to this animal.…”

Section: Discussionmentioning

confidence: 99%

Signature whistle use and changes in whistle emission rate in a rehabilitated rough-toothed dolphin

Ramos,

Jones,

Austin

et al. 2023

Front. Mar. Sci.

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Acoustic signals play a crucial role in communication among animals, particularly in dolphins. Signature whistles, one of their most extensively studied vocalizations, enable dolphins to convey their identity to conspecifics through individually distinct whistle contours. However, it remains unclear whether rough-toothed dolphins (Steno bredanensis) also produce signature whistles with individually identifying contours and, if so, whether they are associated with stress and poor health, such as in bottlenose dolphins. To bridge this knowledge gap, we recorded sounds emitted by a live-stranded rough-toothed dolphin during its rehabilitation in May 2017 at Isla Mujeres, Quintana Roo, Mexico. We assessed if the dolphin produced a signature whistle and whether whistle rate, inter-whistle interval, mean low and high frequencies, and blood chemistry measures, changed significantly over time. While isolated from conspecifics during rehabilitation, the dolphin generated a single, repeated, and stereotyped whistle contour that met the previously established SIGnature IDentification criteria for signature whistle emissions for bottlenose dolphins. Whistle characteristics varied over the 11 recording days: whistle rate and inter-whistle interval significantly decreased over time; the number of whistles with preceding echolocation click trains decreased over time; and mean low and high frequencies changed over recording days. We conclude that this rough-toothed dolphin possessed what resembles a signature whistle contour, and the emission of this contour underwent significant changes throughout the rehabilitation process. While our study presents evidence of a single rough-toothed dolphin producing a signature whistle, further research is necessary to determine whether this vocal behavior is prevalent across the species.

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Section: Discussionmentioning

confidence: 99%

Signature whistle use and changes in whistle emission rate in a rehabilitated rough-toothed dolphin

Ramos,

Jones,

Austin

et al. 2023

Front. Mar. Sci.

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Section: Methodsmentioning

confidence: 99%

“…Whistle contours (shape of the whistle) were obtained using Beluga software (https://synergy.st-andrews.ac.uk/ soundanalysis) within MATLAB (Math-Works, Natick, Massachusetts, USA). Whistles with low signal-to-noise ratio or abundant non-linear features [25] that obscured the shape of the whistle could not be included in the analysis. Beluga contours were analyzed within the adaptive resonance theory neural network (ARTwarp; vigilance threshold of 96%; [26]) to identify when a whistle reoccurred.…”

Section: Plos Onementioning

confidence: 99%

Vocal signatures affected by population identity and environmental sound levels

Fandel,

Silva,

Bailey

2024

PLoS ONE

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Passive acoustic monitoring has improved our understanding of vocalizing organisms in remote habitats and during all weather conditions. Many vocally active species are highly mobile, and their populations overlap. However, distinct vocalizations allow the tracking and discrimination of individuals or populations. Using signature whistles, the individually distinct calls of bottlenose dolphins, we calculated a minimum abundance of individuals, characterized and compared signature whistles from five locations, and determined reoccurrences of individuals throughout the Mid-Atlantic Bight and Chesapeake Bay, USA. We identified 1,888 signature whistles in which the duration, number of extrema, start, end, and minimum frequencies of signature whistles varied significantly by site. All characteristics of signature whistles were deemed important for determining from which site the whistle originated and due to the distinct signature whistle characteristics and lack of spatial mixing of the dolphins detected at the Offshore site, we suspect that these dolphins are of a different population than those at the Coastal and Bay sites. Signature whistles were also found to be shorter when sound levels were higher. Using only the passively recorded vocalizations of this marine top predator, we obtained information about its population and how it is affected by ambient sound levels, which will increase as offshore wind energy is developed. In this rapidly developing area, these calls offer critical management insights for this protected species.

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“…Previous studies also suggested that NLP can facilitate the transmission of indexical cues to conspecifics, including individual identity, and that they can be exploited thanks to natural selection (Fitch et al 2002 ). Besides adaptive explanations, other evidence indicates that nonlinear vocal dynamics may be a mere by-product of physiological constraints involving a certain degree of vocal fatigue (Riede et al 2004 ; Boucher 2008 ; Krajewski et al 2010 ; Weissmann et al 2020 ; Sportelli et al 2022 ). As such, fatigue may reflect a short-term effort necessary for dealing with challenging vocal performances (Weissmann et al 2020 ) or a long-term one due to constant intense activity over time, for example during a season (Vannoni and McElligott 2009 ).…”

Section: Introductionmentioning

confidence: 99%

Singing more, singing harsher: occurrence of nonlinear phenomena in a primate’ song

et al. 2023

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Nonlinear phenomena (NLP) in animal vocalizations arise from irregularities in the oscillation of the vocal folds. Various non-mutually exclusive hypotheses have been put forward to explain the occurrence of NLP, from adaptive to physiological ones. Non-human primates often display NLP in their vocalizations, yet the communicative role of these features, if any, is still unclear. We here investigate the occurrence of NLP in the song of a singing primate, the indri (Indri indri), testing for the effect of sex, age, season, and duration of the vocal display on their emission. Our results show that NLP occurrence in indri depends on phonation, i.e., the cumulative duration of all the units emitted by an individual, and that NLP have higher probability to be emitted in the later stages of the song, probably due to the fatigue indris may experience while singing. Furthermore, NLP happen earlier in the vocal display of adult females than in that of the adult males, and this is probably due to the fact that fatigue occurs earlier in the former because of a greater contribution within the song. Our findings suggest, therefore, that indris may be subjected to physiological constraints during the singing process which may impair the production of harmonic sounds. However, indris may still benefit from emitting NLP by strengthening the loudness of their signals for better advertising their presence to the neighboring conspecific groups.

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Non-linear phenomena: a common acoustic feature of bottlenose dolphin (Tursiops truncatus) signature whistles

Cited by 7 publications

References 69 publications

Signature whistle use and changes in whistle emission rate in a rehabilitated rough-toothed dolphin

Signature whistle use and changes in whistle emission rate in a rehabilitated rough-toothed dolphin

Vocal signatures affected by population identity and environmental sound levels

Singing more, singing harsher: occurrence of nonlinear phenomena in a primate’ song

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