Bottlenose dolphins of Montenegro: Abundance Estimation and Residency Patterns

Akkaya, Aylin; Ruegg, Noemi; Awbery, Tim; Vélez, Natalia; Goossens, Cedric; Papadopoulo, Kenn; Abbiss, Lucy

doi:10.1109/metrosea52177.2021.9611636

Cited by 2 publications

(2 citation statements)

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“…It is important to understand the role of harmonics, specifically considering their high occurrence in each location during the current study. Although this study focuses on geographical differences of whistle variables between study locations, previous studies indicated that 50% of focal bottlenose dolphin groups in Montenegro were observed with the presence of subadults, with dolphins spending 70% of their time travelling, while milling and socialising behaviour only formed 10% or less of the total behavioural budget (Clarkson et al, 2020;Akkaya et al, 2021;Rudd et al, 2022). Above all, both of the locations have a significant amount of marine traffic; with approximately 4,130 vessels in the port of Taranto per year (Shipnext.com).…”

Section: Discussionmentioning

confidence: 99%

“…The majority of the effort in the Adriatic and Ionian Sea focuses on behavioural activity, individual identification, threat assessment and movement patterns (Bearzi et al, 1997;Fortuna et al, 2011;Bas ȩt al., 2017a;Bas ̧et al, 2017b;Awbery et al, 2019;Akkaya et al, 2021). Based on previous knowledge, bottlenose dolphins are generally known as a resident species with limited movement (Genov et al, 2009;Bearzi et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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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%