Movement Patterns of Odontocetes Through Space and Time

Bräger, Stefan; Bräger, Zsuzsanna

doi:10.1007/978-3-030-16663-2_6

Cited by 6 publications

(5 citation statements)

References 103 publications

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“…Possibly, when food resources are scarce, some individuals may travel longer distances to where similar, and more abundant food resources may be available. In less productive habitats such as oceanic waters, animals can be expected to have larger home ranges because there is a need to range further to find sufficient food ( Silva et al, 2008 ; Bräger & Bräger, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

Large-scale movements of common bottlenose dolphins in the Atlantic: dolphins with an international courtyard

Dinis

Molina

Tobeña

et al. 2021

PeerJ

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Wide-ranging connectivity patterns of common bottlenose dolphins (Tursiops truncatus) are generally poorly known worldwide and more so within the oceanic archipelagos of Macaronesia in the North East (NE) Atlantic. This study aimed to identify long-range movements between the archipelagos of Macaronesia that lie between 500 and 1,500 km apart, and between Madeira archipelago and the Portuguese continental shelf, through the compilation and comparison of bottlenose dolphin’s photo-identification catalogues from different regions: one from Madeira (n = 363 individuals), two from different areas in the Azores (n = 495 and 176), and four from different islands of the Canary Islands (n = 182, 110, 142 and 281), summing up 1791 photographs. An additional comparison was made between the Madeira catalogue and one catalogue from Sagres, on the southwest tip of the Iberian Peninsula (n = 359). Results showed 26 individual matches, mostly between Madeira and the Canary Islands (n = 23), and between Azores and Madeira (n = 3). No matches were found between the Canary Islands and the Azores, nor between Madeira and Sagres. There were no individuals identified in all three archipelagos. The minimum time recorded between sightings in two different archipelagos (≈ 460 km apart) was 62 days. Association patterns revealed that the individuals moving between archipelagos were connected to resident, migrant and transient individuals in Madeira. The higher number of individuals that were re-sighted between Madeira and the Canary Islands can be explained by the relative proximity of these two archipelagos. This study shows the first inter-archipelago movements of bottlenose dolphins in the Macaronesia region, emphasizing the high mobility of this species and supporting the high gene flow described for oceanic dolphins inhabiting the North Atlantic. The dynamics of these long-range movements strongly denotes the need to review marine protected areas established for this species in each archipelago, calling for joint resolutions from three autonomous regions belonging to two EU countries.

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Section: Discussionmentioning

confidence: 99%

Large-scale movements of common bottlenose dolphins in the Atlantic: dolphins with an international courtyard

Dinis

Molina

Tobeña

et al. 2021

PeerJ

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“…Additionally, the presence of tides in channels can concentrate fish and impact the local distribution and foraging behaviour of cetaceans, as demonstrated in certain areas (Anderwald et al ., 2012). Food availability has been identified as the main factor influencing the spatial, behavioural and foraging strategies of delphinids (Bräger and Bräger, 2019). Marine environments are complex, three-dimensional habitats with specific physical and chemical regimes (Bräger et al ., 2003).…”

Section: Discussionmentioning

confidence: 99%

Assessing Guiana dolphin abundance and density in the Southwestern Atlantic: insights from conservation areas

Almeida¹,

Percequillo²,

Rollo³

2023

J. Mar. Biol. Ass.

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Accurate demographic data play a critical role in implementing conservation strategies and identifying key areas for species preservation. The population abundance and density of Sotalia guianensis were estimated in the estuarine-lagoon complex of Cananéia, Brazil, using distance sampling. The survey covered 1339.91 km with 83 h 05 min in effort. A half-normal model with cosine adjustments was evaluated as the best fit to estimate an abundance of 193 individuals (95% CI 158–237) and a density of 2.55 ind km−2. The majority of sightings occurred in the Baía de Trapandé (48.72%), followed by the Mar de Cananéia (32.72%) and Mar de Cubatão (18.56%), the three areas surrounding the Ilha de Cananéia. The study confirmed the heterogeneous distribution of the estuary and found that the Mar de Cananéia and the Baía de Trapandé were more densely populated, with 2.76 ind km−2 (95% CI 1.93–3.96) and 2.76 ind km−2 (95% CI 2.07–3.66), respectively, while the Mar de Cubatão was less densely populated, with 1.59 ind km−2 (95% CI 1.04–2.44). The findings support previous research indicating a stable population over the last few decades. The Cananéia estuary is an ecologically diverse region located between protected areas under different categories of environmental protection and harbours a significant population of S. guianensis, providing essential resources for feeding and breeding. Protected areas have proven to be effective tools for preserving both marine and terrestrial environments. Despite the close proximity to humans and constant threats, the study underscores the importance of the area for the conservation of the species.

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“…Therefore, a high abundance of their prey is not necessarily related to high surface productivity where DMS is produced. Also, as deep divers do not usually move over large distances for foraging and show high foraging site fidelity (Bräger & Bräger, 2019), they are less likely to use longrange cues to find their prey. No significant difference was observed in pilot whale surface behaviors between DMS and CTL trials, except for a small increase in the occurrence of spyhopping with DMS.…”

Section: Discussionmentioning

confidence: 99%

A field study of chemical senses in bottlenose dolphins and pilot whales

Bouchard

Barnagaud

Verborgh

et al. 2021

The Anatomical Record

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For most marine vertebrates, chemical cues provide crucial information during navigation and foraging, but their use by cetaceans is still poorly understood. In contrast to baleen whales, toothed whales (odontocetes) are scarcely equipped for chemoreception: they lack the conventional anatomical structures (i.e., olfactory epithelium, nerves and bulbs) involved in olfaction and have reduced taste buds on the tongue. Several behavioral studies have however shown that captive dolphins can perceive chemical solutions, including odorants, in their oral cavity. To investigate whether odontocetes could use infochemicals in their foraging ecology, we implemented a behavioral response experiment in wild bottlenose dolphins and long-finned pilot whales. We tested dimethyl sulfide (DMS) as a potentially attractive stimulus since it is a chemical signature of highly productive marine areas, known to attract several marine predators including fishes and seabirds.We assessed cetacean responses to DMS exposure by analyzing their movements and surface behaviors recorded by onboard observers. In both species, results did not reveal any significant attraction or behavioral reaction toward DMS when compared to a control chemical stimulus, apart from a short-distance response in bottlenose dolphins. These results suggest that while odontocetes may perceive DMS in water, it apparently does not play a significant role in their foraging ecology. Testing potentially more attractive compounds such as prey extracts with the present method and analyzing surface, underwater and acoustic responses would provide further insights on odontocete feeding behavior. It would also provide valuable clues to studies on the anatomical structures involved in their chemosenses.

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Movement Patterns of Odontocetes Through Space and Time

Cited by 6 publications

References 103 publications

Large-scale movements of common bottlenose dolphins in the Atlantic: dolphins with an international courtyard

Large-scale movements of common bottlenose dolphins in the Atlantic: dolphins with an international courtyard

Assessing Guiana dolphin abundance and density in the Southwestern Atlantic: insights from conservation areas

A field study of chemical senses in bottlenose dolphins and pilot whales

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