Dolphin whistle repertoires around São Miguel (Azores): Are you common or spotted?

Gannier, Alexandre; Fuchs, Sandra Cristina Pereira Costa; Gannier, Adrien; Fernández, Marc; Neto, Ana I.

doi:10.1016/j.apacoust.2019.107169

Cited by 4 publications

(2 citation statements)

References 31 publications

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“…It has been further suggested that increased underwater noise in the close proximity of boats may result in the production of harmonics, with the number of harmonic vocalisations having been observed to increase with calf presence and a larger group size (La Manna et al, 2019). However, it is important to consider that the production of harmonics may vary among species (Gannier et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Akkaya¹,

Awbery

Medcalf³

et al. 2023

Front. Mar. Sci.

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Bottlenose dolphins have a complex vocal repertoire that varies depending on behavioral context, social structure, group composition, and anthropogenic pressures. This current study describes the whistle characteristics of bottlenose dolphins for the first time in the South Adriatic Sea while assessing the potential differences between whistle characteristics of geographically separated dolphins within neighbouring waters of the North Ionian Sea. The results show that whistle characteristics were similar between Taranto Gulf (Italy) and Boka Bay (Montenegro), despite their spatial differences. The mean peak frequency was 10kHz for each study location while the mean minimum and maximum frequency ranged from 7 to 14kHz. The average duration of whistles was 500 milliseconds. These results share similarities with previous literature, although several studies reported slightly different mean peak frequencies, ranging up to 15kHz in the neighbouring waters of Croatia and Italy. Further, harmonics were produced and formed in 40% of the whistles in Taranto Gulf and 30% of the whistles in Boka Bay. A high incidence of harmonics has previously been associated with behavioral states (i.e., travelling) and with certain types of marine traffic (i.e., fishing vessels). Therefore, it is important to collect simultaneous data on the visual behavior of the focal group as well as document the type and density of marine traffic within the proximity of the dolphins to have an in-depth understanding of vocal behavior. Despite the similarities of whistle characteristics of Taranto and Boka Bay, the whistle contours showed notable variations. Upsweep whistles were the most regularly produced whistle type in each location, which coincides with previous studies in the Mediterranean Sea. However, the least produced whistle had a concave contour in Taranto and was flat in Boka Bay. Previous studies have confirmed that flat whistles account for the least produced whistle contour in the Mediterranean Basin. Examining the whistle characteristics and the variation in whistle contours provides an in-depth understanding of the behavioral complexity as well as its plasticity in the presence of pressure. Therefore, future studies need to include behavior, group composition, noise levels, and human presence to enable an effective understanding of variation in whistle characteristics of bottlenose dolphins.

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Section: Discussionmentioning

confidence: 99%

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Akkaya¹,

Awbery

Medcalf³

et al. 2023

Front. Mar. Sci.

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“…Whistle parameters of dolphins showed intra and interspecific differences and they can be used to classify and distinguish species and populations ( Ansmann et al, 2007 ; Azevedo & Van Sluys, 2005 ; Morisaka et al, 2005 ; Rendell et al, 1999 ). While studies investigating the whistle repertoire of short-beaked common dolphins are relatively abundant ( Ansmann et al, 2007 ; Azzolin et al, 2021 ; Fearey et al, 2019 ; Gannier et al, 2020 ; Gannier et al, 2010 ; Pagliani et al, 2022 ; Papale et al, 2014 ; Petrella et al, 2012 ), only few focused on the acoustics of long-beaked common dolphins ( Caldwell & Caldwell, 1968 ; Oswald, Barlow & Norris, 2003 ; Oswald et al, 2007 ; Oswald et al, 2021a ; Oswald et al, 2021b ), of which none in the Gulf of California. Indeed, in the study area the investigations on this species have mainly been isotopic analyses and population studies ( Aurioles-Gamboa et al, 2013 ; Niño Torres et al, 2006 ; Vidal & Gallo-Reynoso, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Whistle characterization of long-beaked common dolphin (Delphinus delphis bairdii) in La Paz Bay, Gulf of California

Carlón-Beltrán,

Viloria-Gómora,

Urbán R.

et al. 2023

PeerJ

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Long-beaked common dolphin (Delphinus delphis bairdii) distribution is limited to the Eastern North Pacific Ocean. Its whistle repertoire is poorly investigated, with no studies in the Gulf of California. The aim of the present study is to characterize the whistles of this species and compare their parameters with different populations. Acoustic monitoring was conducted in La Paz Bay, Gulf of California. Recordings were inspected in spectrogram view in Raven Pro, selecting good quality whistles (n = 270). In the software Luscinia, contours were manually traced to obtain whistle frequencies and duration. Number of steps, inflection points and contour type were visually determined. We calculated the descriptive statistics of the selected whistle parameters and we compared the results with a dolphins population from the Eastern Pacific Ocean. Permutational multivariate analysis of variance (PERMANOVA) was performed to test the intraspecific variation of the whistle parameters among groups. In the present study the mean values (±SD) of the whistle parameters were: maximum frequency = 14.13 ± 3.71 kHz, minimum frequency = 8.44 ± 2.58 kHz and duration = 0.44 ± 0.31 s. Whistles with the upsweep contour were the most common ones (34.44%). The coefficient of variation (CV) values for modulation parameters were high (>100%), in accordance with other studies on dolphins. Whistle parameters showed significant differences among groups. Finally, ending and maximum frequencies, duration and inflection points of the whistles recorded in the present study were lower compared with the parameters of the long-beaked common dolphins from the Eastern Pacific Ocean. This study provides the first whistle characterization of long-beaked common dolphin from the Gulf of California and it will help future passive acoustic monitoring applications in the study area.

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Acoustic Detection and Recognition of Dolphins using Swarm Intelligence Neural Networks

Khishe

Mohammadi

et al. 2021

Applied Ocean Research

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Dolphin whistle repertoires around São Miguel (Azores): Are you common or spotted?

Cited by 4 publications

References 31 publications

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Whistle characterization of long-beaked common dolphin (Delphinus delphis bairdii) in La Paz Bay, Gulf of California

Acoustic Detection and Recognition of Dolphins using Swarm Intelligence Neural Networks

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