scholarly journals On the behaviour of an under-studied population of bottlenose dolphins in the Southern Adriatic Sea

2018 ◽  
Vol 99 (4) ◽  
pp. 1017-1023 ◽  
Author(s):  
Flavio Affinito ◽  
Cristobal Olaya Meza ◽  
Aylin Akkaya Bas ◽  
Deborah Brill ◽  
Guy Whittaker ◽  
...  
Keyword(s):  
Group Size ◽  
Bottlenose Dolphin ◽  
Adriatic Sea ◽  
Bottlenose Dolphins ◽  
Anthropogenic Pressure ◽  
Social Predictors ◽  
Dolphin Population ◽  
Autumn And Winter ◽  
Effective Conservation ◽  
Study Monitoring

AbstractPerhaps the world's best-known cetacean, the bottlenose dolphin shows considerable variation in behaviour between and within populations in relation to differences in natural and anthropogenic conditions. Drivers of behavioural variation need to be identified to understand the dynamics of wild dolphin populations. Little research has been published on the bottlenose dolphin population found in the Southern Adriatic Sea. Using a set of spatial, temporal and social predictors, we aimed to investigate what variables are related to the behaviour of an under-studied population of bottlenose dolphins along the coastline of Montenegro. We present the results of a year-long study monitoring the behaviour of bottlenose dolphins along coastal Montenegro. We considered the effect of topography, seasonality and group size. A large proportion of travelling (55%) small groups (mean 4, range 1–9) in shallow waters (<50 m) was observed. We showed that seasonality alone explained behaviour best, with surface-feeding and socializing-resting increasing in autumn and winter. Group size was found to be a result of behavioural choice. We suggest seasonal changes in environmental conditions and anthropogenic pressure may explain the recorded behavioural pattern. This research points to the necessity of increased collaboration in the region to help understand complex patterns in behaviour and habitat use of local dolphin populations if effective conservation measures are to be developed.

Bottlenose dolphins at the southern extreme of the south-western Atlantic: local population decline?

2011 ◽  
Vol 92 (8) ◽  
pp. 1843-1849 ◽  
Author(s):  
Mariano A. Coscarella ◽  
Silvana L. Dans ◽  
Mariana Degrati ◽  
Griselda V. Garaffo ◽  
Enrique A. Crespo
Keyword(s):  
Group Size ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Local Population ◽  
Population Decline ◽  
San Jose ◽  
Western Atlantic ◽  
Right Whale ◽  
Dolphin Population ◽  
Monitoring Protocols

The management scheme of Marine Protected Areas (MPAs) includes monitoring protocols but such activities are not always carried out. This is the case for Golfo San José, a MPA in northern Patagonia, Argentina. It was created in 1975 for the protection of the southern right whale (Eubalaena australis) breeding grounds. Other components of the system, such as dolphin populations have received little attention. This study is the first attempt to estimate sighting rates, group size and overall abundance of a bottlenose dolphin (Tursiops truncatus) population in Golfo San José and adjacent areas after 30 years. An analysis of the seasonal sighting rates indicates that bottlenose dolphins were present in the study area throughout the year but a decline in group size and abundance and major shift in distribution was detected when compared with previous published reports. The settlement of the MPA failed to secure the persistence of the bottlenose dolphin population within its boundaries. Possible explanations for the detected decline are addressed including increased natural mortality, human induced mortality and disturbance, resources depletion and environmental shift.

scholarly journals The bottlenose dolphin Tursiops truncatus foraging around a fish farm: Effects of prey abundance on dolphins’ behavior

2009 ◽  
Vol 55 (4) ◽  
pp. 243-248 ◽  
Author(s):  
Bruno Díaz López
Keyword(s):  
Group Size ◽  
Human Activities ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Dive Duration ◽  
Fish Farm ◽  
Prey Abundance ◽  
Diving Behavior ◽  
Top Predators ◽  
Feeding Activities

Abstract The extent to which prey abundance influences both bottlenose dolphin foraging behavior and group size in the presence of human activities has not previously been studied. The primary aim of this study was to identify and quantify how wild bottlenose dolphins respond, individually and as groups, to the relative abundance of prey around a fish farm. Detailed views of dolphins’ behavior were obtained by focal following individual animals whilst simultaneously collecting surface and underwater behavioral data. A total of 2150 dive intervals were analyzed, corresponding to 342 focal samples, lasting over 34 hours. Bottlenose dolphins remained submerged for a mean duration of 46.4 seconds and a maximum of 249 seconds. This study provides the first quantified data on bottlenose dolphin diving behavior in a marine fin-fish farm area. This study’s results indicate that within a fish farm area used intensively by bottlenose dolphins for feeding, dolphins did not modify dive duration. Additionally, underwater observations confirmed that dolphins find it easier to exploit a concentrated food source and it appears that hunting tactic and not group size plays an important role during feeding activities. Thus, bottlenose dolphins appear capable of modifying their hunting tactics according to the abundance of prey. When top predators display behavioral responses to activities not directed at them, the task of studying all possible effects of human activities can become even more challenging.

Use of photo-identification data to quantify mother–calf association patterns in bottlenose dolphins

2003 ◽  
Vol 81 (8) ◽  
pp. 1421-1427 ◽  
Author(s):  
Kate Grellier ◽  
Philip S Hammond ◽  
Ben Wilson ◽  
Carol A Sanders-Reed ◽  
Paul M Thompson
Keyword(s):  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Small Population ◽  
Association Patterns ◽  
Photo Identification ◽  
Dolphin Population ◽  
The Mean ◽  
First Time

For social mammals living in fission–fusion societies, the mother–infant bond is long and extends beyond the nursing period. We successfully developed a technique, using photo-identification data, to quantify mother–calf association patterns in a small population of bottlenose dolphins, Tursiops truncatus, off eastern Scotland. By statistically comparing association indices between young calves and their associates we assigned 17 individual adults as mothers to 20 young calves with a 5% level of probability. The mean index of association between calves and mothers remained high until at least year 8 of life. While calves were still found in the same schools as their mother, they surfaced beside her less often as their age increased. This is the first time that the mother–calf bond has been quantitatively assessed for any bottlenose dolphin population inhabiting temperate waters. Results are compared with those from subtropical populations and are discussed with respect to the viability of this population.

Mid-distance re-sighting of a common bottlenose dolphin in the northern Adriatic Sea: insight into regional movement patterns

2015 ◽  
Vol 96 (4) ◽  
pp. 909-914 ◽  
Author(s):  
Tilen Genov ◽  
Valeria Angelini ◽  
Ana Hace ◽  
Giuseppe Palmisano ◽  
Boris Petelin ◽  
...  
Keyword(s):  
Bottlenose Dolphin ◽  
Adriatic Sea ◽  
Animal Movement ◽  
Bottlenose Dolphins ◽  
Movement Patterns ◽  
Population Level ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Common Bottlenose Dolphin ◽  
Insight Into

Understanding animal movement patterns is not only important for providing insight into their biology, but is also relevant to conservation planning. However, in aquatic and wide-ranging species such as cetaceans, this is often difficult. The common bottlenose dolphin (Tursiops truncatus) is the most common cetacean in the northern and central Adriatic Sea and has been the focus of long-term studies in some areas. All of the studied local populations show a relatively high degree of site fidelity, but their movements, ranging patterns or connectivity are not well understood. On 24 and 26 April 2014 a single adult bottlenose dolphin was observed and photographed alive off the Slovenian coast. The same individual was found dead on the shores of Goro, Italy, on 5 May 2014, about 130 km from the two sighting locations. The well-marked dorsal fin made the identification straightforward. The dolphin was found freshly dead, suggesting it had died very recently prior to being found. This indicates that the reported movement was a real one, rather than an artefact of currents. Although single cases cannot provide the basis for making population-level inferences, our observation shows that northern Adriatic bottlenose dolphins can make substantial movements in short periods of time and suggests that such movements could be more common than currently documented. Comparisons among photo-ID catalogues and stranding events can be highly informative, as they can provide useful information with implications for the cross-border conservation of mobile marine predators.

scholarly journals Pregnancy and Fetal Development: Cephalic Presentation and Other Descriptive Ultrasonographic Findings from Clinically Healthy Bottlenose Dolphins (Tursiops truncatus) under Human Care

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 908
Author(s):  
Pietro Saviano ◽  
Letizia Fiorucci ◽  
Francesco Grande ◽  
Roberto Macrelli ◽  
Alessandro Troisi ◽  
...  
Keyword(s):  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Invasive Technique ◽  
Medical Procedures ◽  
Non Invasive ◽  
Dolphin Population ◽  
Human Care ◽  
First Time

Ultrasonography is widely used in veterinary medicine for the diagnosis of pregnancy, and can also be used to monitor abnormal pregnancies, embryonic resorption, or fetal abortion. Ultrasonography plays an important role in modern-day cetacean preventative medicine because it is a non-invasive technique, it is safe for both patient and operator, and it can be performed routinely using trained responses that enable medical procedures. Reproductive success is an important aspect of dolphin population health, as it is an indicator of the future trajectory of the population. The aim of this study is to provide additional relevant data on feto-maternal ultrasonographic monitoring in bottlenose dolphin (Tursiops truncatus) species, for both the clinicians and for in situ population studies. From 2009 to 2019, serial ultrasonographic exams of 11 healthy bottlenose dolphin females kept under human care were evaluated over the course of 16 pregnancies. A total of 192 ultrasound exams were included in the study. For the first time, the sonographic findings of the bottlenose dolphin organogenesis and their correlation with the stage of pregnancy are described. Furthermore, this is the first report that forecasts the cephalic presentation of the calf at birth, according to its position within the uterus.

Further evidence of a context-specific agonistic signal in bottlenose dolphins: the influence of consortships and group size on the pop vocalization

Behaviour ◽  
2015 ◽  
Vol 152 (14) ◽  
pp. 1979-2000 ◽  
Author(s):  
Nicole L. Vollmer ◽  
Lee-Ann C. Hayek ◽  
Michael R. Heithaus ◽  
Richard C. Connor
Keyword(s):  
Regression Analysis ◽  
Group Size ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Low Frequency ◽  
Shark Bay ◽  
Average Group ◽  
Context Specific ◽  
Male Alliances ◽  
Average Group Size

Pops are a low-frequency, pulsed vocalization produced by Indo-Pacific bottlenose dolphins (Tursiopscf.aduncus) in Shark Bay, Western Australia and are often heard when male alliances are consorting or ‘herding’ a female. Previous research indicated that pops produced in this context are an agonistic ‘come-hither’ demand produced by males and directed at female consorts. Here we examine pop occurrence during focal follows on bottlenose dolphin alliances with and without female consorts present. Regression analysis was conducted to determine if pop numbers were higher in the presence of female consorts, and if variables including group size alone and the interaction between presence/absence of a consortship and group size, influenced pop production. While the presence or absence of a consortship significantly affected the number of pops, average group size had no significant effect on pop production. Our research provides further evidence that the pop vocalization plays an important role in consortships.

scholarly journals Female reproductive output in a Mediterranean bottlenose dolphin Tursiops truncatus population

2020 ◽  
Vol 29 ◽  
pp. 123-136
Author(s):  
MF Blasi ◽  
C Bruno ◽  
L Boitani
Keyword(s):  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Reproductive Output ◽  
Bottlenose Dolphins ◽  
Reproductive Pattern ◽  
Photo Identification ◽  
Conservation Actions ◽  
Dolphin Population ◽  
The Mean ◽  
June July

The reproductive output of wild bottlenose dolphins Tursiops truncatus has extensively been investigated; nevertheless, it remains widely unexplored in the Mediterranean Sea. We investigated the reproductive history of female bottlenose dolphins in the Aeolian Archipelago (Italy). Thirteen years of photo-identification data were used to track the reproductive pattern of 7 females and their 16 calves. The birth period was accurately estimated within 1 mo for 6 calves (37.5%), peaking in June/July. The mean number of calves for females was 2.3 ± 1.1 (SD), ranging from 1 to 4. The mean interbirth interval was 3.5 ± 1.6 yr, ranging from 2 to 7 yr. The mean weaning age was 3.2 ± 0.6 yr, although 1 calf may have been weaned as late as its fifth birthday. Mother-calf postweaning associations were tracked for 9 calves and ranged from 4 to 10 yr of residence in the maternal group of the calf. The age of first pregnancy was 7.5 yr. The number of calves was influenced by the mean maternal group size, with females that were sighted in larger groups having more calves. However, the number of calves was not influenced by the strength of the associations of mothers with other females. Calf mortality by age 1 was high (12.5%). Two juveniles also died postweaning within 6 yr of their birth. Finally, 2 females may have died during the study, as they were not re-sighted at the end of the study. Our results highlight the need to implement urgent conservation actions to protect this bottlenose dolphin population.

scholarly journals Report of the Working Group on Interactions between Humans and Tursiops truncatus in the Southwest Atlantic Ocean

2017 ◽  
Vol 11 (1-2) ◽  
pp. 79-98 ◽  
Author(s):  
Pedro Friedrich Fruet ◽  
Camilah A. Zappes ◽  
Tatiana L. Bisi ◽  
Paulo César Simões-Lopes ◽  
Paula Laporta ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Habitat Modification ◽  
Positive Interactions ◽  
Contamination Level ◽  
Great Effort ◽  
Anthropogenic Pressure ◽  
Southwest Atlantic ◽  
In The Wild

In this work we compiled the available information about humans and bottlenose dolphin interactions in the Southwest Atlantic Ocean (SWAO), including issues as historical direct takes, incidental captures in fisheries, positive interactions with fisheries, interactions of dolphins with tourism and boat traffic, habitat modification or degradation, and environmental pollution. The data compiled in this review demonstrated that coastal bottlenose dolphins are under anthropogenic pressure in the SWAO. Direct take of bottlenose dolphins in the wild does not appear to be an issue of conservation concern in the SWAO. Although the species is exposed to bioaccumulation of micropollutants, it is suggested that contamination level is lower when compared to bottlenose dolphins from other continents. Coastal works can impact bottlenose dolphin behavior and habitat use in a short-term, but those seem to be reversible when works stop. Bycatch occurs throughout the species distribution and seems to be occasional in Uruguayan and Argentinean waters, where there is evidence of a historic decline in dolphin sightings. In Brazil, bycatch is apparently low in the northeast and southeast coasts, but is frequent in certain areas of southern Brazil. Studies on the subject are scarce or preliminary and a great effort is still required to understand the real impact of human activities on bottlenose dolphins in the SWAO.  

scholarly journals Genetic divergence and fine scale population structure of the common bottlenose dolphin (Tursiops truncatus, Montagu) found in the Gulf of Guayaquil, Ecuador

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4589 ◽  
Author(s):  
Rosa de los Ángeles Bayas-Rea ◽  
Fernando Félix ◽  
Rommel Montufar
Keyword(s):  
Population Structure ◽  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Western Coast ◽  
Common Bottlenose Dolphin ◽  
Dolphin Population ◽  
The Common ◽  
Gulf Of Guayaquil ◽  
Outer Estuary

The common bottlenose dolphin, Tursiops truncatus, is widely distributed along the western coast of South America. In Ecuador, a resident population of bottlenose dolphins inhabits the inner estuarine area of the Gulf of Guayaquil located in the southwestern part of the country and is under threat from different human activities in the area. Only one genetic study on South American common bottlenose dolphins has been carried out to date, and understanding genetic variation of wildlife populations, especially species that are identified as threatened, is crucial for defining conservation units and developing appropriate conservation strategies. In order to evaluate the evolutionary link of this population, we assessed the phylogenetic relationships, phylogeographic patterns, and population structure using mitochondrial DNA (mtDNA). The sampling comprised: (i) 31 skin samples collected from free-ranging dolphins at three locations in the Gulf of Guayaquil inner estuary, (ii) 38 samples from stranded dolphins available at the collection of the “Museo de Ballenas de Salinas,” (iii) 549 mtDNA control region (mtDNA CR) sequences from GenBank, and (iv) 66 concatenated sequences from 7-mtDNA regions (12S rRNA, 16S rRNA, NADH dehydrogenase subunit I–II, cytochrome oxidase I and II, cytochrome b, and CR) obtained from mitogenomes available in GenBank. Our analyses indicated population structure between both inner and outer estuary dolphin populations as well as with distinct populations of T. truncatus using mtDNA CR. Moreover, the inner estuary bottlenose dolphin (estuarine bottlenose dolphin) population exhibited lower levels of genetic diversity than the outer estuary dolphin population according to the mtDNA CR. Finally, the estuarine bottlenose dolphin population was genetically distinct from other T. truncatus populations based on mtDNA CR and 7-mtDNA regions. From these results, we suggest that the estuarine bottlenose dolphin population should be considered a distinct lineage. This dolphin population faces a variety of anthropogenic threats in this area; thus, we highlight its fragility and urge authorities to issue prompt management and conservation measures.

scholarly journals Social structure of a population of bottlenose dolphins (Tursiops truncatus) in the oceanic archipelago of Madeira, Portugal

2017 ◽  
Vol 98 (5) ◽  
pp. 1141-1149 ◽  
Author(s):  
Ana Dinis ◽  
Filipe Alves ◽  
Cátia Nicolau ◽  
Cláudia Ribeiro ◽  
Manfred Kaufmann ◽  
...  
Keyword(s):  
Social Structure ◽  
Bottlenose Dolphin ◽  
Bottlenose Dolphins ◽  
Association Index ◽  
Photo Identification ◽  
Open Population ◽  
Time Period ◽  
Dolphin Population ◽  
Identification Analysis ◽  
Over Time

In order to investigate social structure, 11 years of individual photo-identification data of bottlenose dolphin were analysed. We examined the type of association indices between pairs of identified individuals; the patterns of affiliation between individual dolphins and the probabilities of association between individuals over time. Between 2001 and 2012, there were 272 encounters which resulted in the identification of 501 individuals. The discovery curve resulting from the photo-identification analysis indicated an open population with regular recruitment of new individuals. All individuals were found to be associated at an association index of <0.05. A total of 291 individuals recorded from 2004 to 2012 were used to assess the temporal pattern of the social structure. The model fit to the Standardized Lagged Association Rate (SLAR) that best described the studied bottlenose dolphin population was ‘casual acquaintances’, and the analysis of associations over time showed a decreasing SLAR curve that falls until reaching the null rate, confirming random associations. The decline of the SLAR curve after ~500 days (1.4 years) suggests disassociation over that time period which can be explained by demographic events such as mortality or emigration. In an open ocean habitat like Madeira this is not unexpected, as there are neither geographic boundaries nor enclosed environments. This population presented a dynamic and fluctuating social structure, where groups change in size and composition. In future conservation efforts this population should be considered as one large community, where individuals associate, disassociate and reassociate with each other over time.

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