scholarly journals Assessing the Behavioural Responses of Small Cetaceans to Unmanned Aerial Vehicles

2021 ◽  
Vol 13 (1) ◽  
pp. 156
Author(s):  
Joana Castro ◽  
Francisco O. Borges ◽  
André Cid ◽  
Marina I. Laborde ◽  
Rui Rosa ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Mammal Species ◽  
Minimal Impact ◽  
Behavioural Responses ◽  
Delphinus Delphis ◽  
Aerial Vehicles ◽  
Vtol Uav ◽  
Accessible Method

Unmanned Aerial Vehicles (UAVs), or drones, have recently emerged as a relatively affordable and accessible method for studying wildlife. Vertical Take-off and Landing (VTOL) UAVs are appropriate for morphometric, behavioural, abundance and demographic studies of marine mammals, providing a stable, nonintrusive and highly manoeuvrable platform. Previous studies using VTOL UAVs have been conducted on various marine mammal species, but specific studies regarding behavioural responses to these devices are limited and scarce. The aim of this study was to evaluate the immediate behavioural responses of common (Delphinus delphis) and bottlenose (Tursiops truncatus) dolphins to a VTOL UAV flown at different altitudes. A multirotor (quadcopter) UAV with an attached GoPro camera was used. Once a dolphin group was located, the UAV was flown at a starting height of 50 m directly above the group, subsequently descending 5 m every 30 s until reaching 5 m. We assessed three behavioural responses to a VTOL UAV at different heights: (i) direction changes, (ii) swimming speed and (iii) diving. Responses by D. delphis (n = 15) and T. truncatus (n = 10) groups were analysed separately. There were no significant responses of T. truncatus to any of the studied variables. For D. delphis, however, there were statistically significant changes in direction when the UAV was flown at a height of 5 m. Our results indicate that UAVs do not induce immediate behavioural responses in common or bottlenose dolphins when flown at heights > 5 m, demonstrating that the use of VTOL UAVs to study dolphins has minimal impact on the animals. However, we advise the use of the precautionary principle when interpreting these results as characteristics of this study site (e.g., high whale-watching activity) may have habituated dolphins to anthropogenic disturbance.

scholarly journals Behaviour reactions of bottlenose dolphins (Tursiops truncatus) to multirotor Unmanned Aerial Vehicles (UAVs)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ticiana Fettermann ◽  
Lorenzo Fiori ◽  
Martin Bader ◽  
Ashray Doshi ◽  
Dan Breen ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Cost Effective ◽  
Aerial Survey ◽  
Cetacean Species ◽  
Age Class ◽  
Aerial Vehicles ◽  
Vtol Uav ◽  
Aerial Observation

Abstract Unmanned aerial vehicles (UAVs) represent a novel and cost effective research tool to investigate cetacean behaviour, as conventional aircraft are expensive, limited in the altitude they can fly at and potentially disturb sensitive wildlife. In addition, the aerial observation from the UAVs allows assessment of cetacean behaviour from an advantageous perspective and can collect high spatial and temporal resolution data, providing the opportunity to gather accurate data about group size, age class and subsurface behaviour. However, concerns have been raised about the potential risks of disturbance to animals caused by the UAV’s visual and acoustic stimuli. Boat-based surveys were conducted to assess the short-term behavioural responses of resting bottlenose dolphins (Tursiops truncatus) to a lightweight Vertical take-off and landing (VTOL) UAV flown at 10, 25, and 40 m altitude. Changes in group swim direction and frequencies of surface and aerial behavioural events were recorded from an anchored research vessel before (control) and during the aerial survey. The number of reorientation and tail slap events increased significantly between controls and flights when the UAV was flown at 10 m over the animals. In contrast, no significant differences were detected when the aircraft was flown at 25 and 40 m altitude. However, a precautionary approach is recommended for research applications requiring lower flight altitudes, with further research recommended to assess how different cetacean species and age class may respond to the UAV presence.

Stomach contents of English Channel cetaceans stranded on the coast of Normandy

2005 ◽  
Vol 85 (6) ◽  
pp. 1539-1546 ◽  
Author(s):  
J.F. De Pierrepont ◽  
B. Dubois ◽  
S. Desormonts ◽  
M.B. Santos ◽  
J.P. Robin
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Stomach Contents ◽  
Important Species ◽  
Stenella Coeruleoalba ◽  
Delphinus Delphis ◽  
Common Squid ◽  
Pilot Whales ◽  
The University ◽  
Common Dolphins

During 1998–2003 stomach contents of 47 marine mammals stranded on the coast of Normandy were analysed. The animals were first examined by a veterinary network and stomach contents were analysed at the University of Caen. The sample comprised: 26 common dolphins (Delphinus delphis), four bottlenose dolphins (Tursiops truncatus), seven harbour porpoises (Phocoena phoecoena), five grey seals (Halichoerus grypus), two long-finned pilot whales (Globicephala melas), one white beaked dolphin (Lagenorhynchus albirostris), one minke whale (Balaenoptera acurostrata) and one striped dolphin (Stenella coeruleoalba). The identification of food items was done using hard parts (i.e. fish otoliths and cephalopod beaks). Diet indices were computed including prey frequency and percentage by number. Common dolphins ate mainly gadoid fish (Trisopterus sp.), gobies and mackerel (Scomber scombrus). Cephalopods occurred in small numbers in the diet and commercially important species (cuttlefish and common squid) were scarce.

scholarly journals Occurrence, distribution and composition of marine mammals in the bight of Bony, Nigeria

2021 ◽  
Vol 15 (1) ◽  
pp. 263-272
Author(s):  
Gideon Wole Olakunle ◽  
Ajuonu Ndubisi
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Atlantic Coast ◽  
Primary Objective ◽  
Depth Range ◽  
Common Dolphin ◽  
Coastal Habitat ◽  
Oil Companies ◽  
Delphinus Delphis ◽  
Marine Vessels

Information on the distribution, occurrence and population structure of cetaceans (whales and dolphins) of the Atlantic coast of Nigeria in West Africa remains fairly sparse to date, with few detailed studies being conducted on this valuable marine resource. This paper highlights the abundant cetacean community sighted in the Nigerian coastal waters and the respective importance of this area as a prime coastal habitat for these mammals. The secondary objective was the evaluation of this resource and development of appropriatemanagement policies. Opportunistic data was collected on board six different marine vessels belonging to some international oil  companies (IOC) in Nigeria, whose primary objective was to conduct seismic operations. 8,327 hours and 36 minutes of effort was logged during 2 wet and 3 dry seasons respectively, covering almost 880 km2 at a depth range of 10 to 70 m. The total number of individuals recorded was 2199 of which 80% were dolphins and 20% were whales. Out of these, 55.14% was sighted at depth range of 21 – 30 m. This was followed by 30.42% recorded at depth range of 31 - 40 m. The least frequency of 0.75 % was recorded at depth range of 61- 70m. Five hundred and twenty-five (525) individual whales was recorded, out of which 77.14% were adults and 22.86% were  juveniles, while 1674 individual dolphins were recorded with 52.63% juveniles and 47.37% adult. Four species of dolphins were  identified. The bottlenose dolphins, Tursiops truncatus was the most abundant owing to the large size of the groups observed, followed by common dolphin, Delphinus delphis. All species of dolphins identified occurred throughout the sampling months. Two species of whales were identified with the humpback whale (Megaptera novaeangliae) predominant and killer whales (Orcinus orca) which seem to be present in just a part of a year. Nigerian coastal water is moderately rich in cetacean diversity, which is currently underreported due to limited research.Keywords: Whales, dolphins, species diversity, opportunistic surveys, Nigeria.

scholarly journals Monitoring marine mammals using unmanned aerial vehicles: quantifying detection certainty

Ecosphere ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. e02122 ◽  
Author(s):  
Ana S. Aniceto ◽  
Martin Biuw ◽  
Ulf Lindstrøm ◽  
Stian A. Solbø ◽  
Fredrik Broms ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Marine Mammals ◽  
Aerial Vehicles

scholarly journals Author Correction: Behaviour reactions of bottlenose dolphins (Tursiops truncatus) to multirotor Unmanned Aerial Vehicles (UAVs)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ticiana Fettermann ◽  
Lorenzo Fiori ◽  
Martin Bader ◽  
Ashray Doshi ◽  
Dan Breen ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Aerial Vehicles

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

scholarly journals Do Pinnipeds have Personality? Broad Dimensions and Contextual Consistency of Behavior in Harbor Seals (Phoca vitulina) and California Sea Lions (Zalophus californianus).

2017 ◽  
Vol 30 ◽  
Author(s):  
Amber J. de Vere ◽  
Malin K. Lilley ◽  
Lauren Highfill
Keyword(s):  
Marine Mammals ◽  
Bottlenose Dolphins ◽  
Routine Activity ◽  
Personality Factors ◽  
Harbor Seals ◽  
Behavioral Consistency ◽  
California Sea Lions ◽  
Mammal Species ◽  
Individual Level ◽  
Sea Lions

Personality has now been studied in species as diverse as chimpanzees and cuttlefish, but marine mammals remain vastly underrepresented in this area. A broad range of traits have been assessed only once in each of bottlenose dolphins and California sea lions, while consistent individual differences in a few specific behaviors have been identified in grey seals. Furthermore, the context component of definitions of personality is not often assessed, despite evidence that animals may show individual patterns of behavioral consistency across contexts. The current study therefore aimed to use behavioral coding to assess underlying personality factors and consistency across contexts in two marine mammal species: California sea lions and harbor seals. In both species, two personality factors were extracted using exploratory factor analysis. Both were broadly similar across species; the first, Boldness, resembled human Extraversion, and to some extent Openness, with sea lions exhibiting a greater social component. The second factor was labeled Routine Activity, and may contain some Conscientiousness-like traits. Species-specific patterns were also identified for interactive behaviors across two contexts. However, there was substantial individual variation in the frequency of these behaviors, as well as some animals who did not conform to group-level trends. This study therefore provides novel evidence for broad personality factors and both group- and individual-level patterns of contextual consistency in two pinniped species.

scholarly journals Vocal correlates of arousal in bottlenose dolphins (Tursiops spp.) in human care

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0250913
Author(s):  
Rachel Probert ◽  
Anna Bastian ◽  
Simon H. Elwen ◽  
Bridget S. James ◽  
Tess Gridley
Keyword(s):  
Production Rate ◽  
Marine Mammals ◽  
Structural Characteristics ◽  
Bottlenose Dolphins ◽  
Social Groups ◽  
Contact Call ◽  
Normal Behaviour ◽  
Behavioural Responses ◽  
Signature Whistles ◽  
Human Care

Human-controlled regimes can entrain behavioural responses and may impact animal welfare. Therefore, understanding the influence of schedules on animal behaviour can be a valuable tool to improve welfare, however information on behaviour overnight and in the absence of husbandry staff remains rare. Bottlenose dolphins (Tursiops spp.) are highly social marine mammals and the most common cetacean found in captivity. They communicate using frequency modulated signature whistles, a whistle type that is individually distinctive and used as a contact call. We investigated the vocalisations of ten dolphins housed in three social groups at uShaka Sea World dolphinarium to determine how patterns in acoustic behaviour link to dolphinarium routines. Investigation focused on overnight behaviour, housing decisions, weekly patterns, and transitional periods between the presence and absence of husbandry staff. Recordings were made from 17h00 – 07h00 over 24 nights, spanning May to August 2018. Whistle (including signature whistle) presence and production rate decreased soon after husbandry staff left the facility, was low over night, and increased upon staff arrival. Results indicated elevated arousal states particularly associated with the morning feeding regime. Housing in the pool configuration that allowed observation of staff activities from all social groups was characterised by an increase in whistle presence and rates. Heightened arousal associated with staff presence was reflected in the structural characteristics of signature whistles, particularly maximum frequency, frequency range and number of whistle loops. We identified individual differences in both production rate and the structural modification of signature whistles under different contexts. Overall, these results revealed a link between scheduled activity and associated behavioural responses, which can be used as a baseline for future welfare monitoring where changes from normal behaviour may reflect shifts in welfare state.

scholarly journals Vocal correlates of arousal in bottlenose dolphins (Tursiops spp.) in human care

2021 ◽  
Author(s):  
Rachel Probert ◽  
Anna Bastian ◽  
Simon Elwen ◽  
Bridget James ◽  
Tess Gridley
Keyword(s):  
Marine Mammals ◽  
Structural Characteristics ◽  
Bottlenose Dolphins ◽  
Contact Call ◽  
Visual Contact ◽  
Normal Behaviour ◽  
Behavioural Responses ◽  
Signature Whistles ◽  
Human Care ◽  
The Impact

Human-controlled regimes can entrain behavioural responses and may impact animal welfare. Therefore, understanding the impact of schedules on animal behaviour can be a valuable tool to improve welfare, however information on overnight behaviour and behaviour in the absence of husbandry staff remains rare. Bottlenose dolphins ( Tursiops spp.) are highly social marine mammals and the most common cetacean found in captivity. They communicate using frequency modulated signature whistles which are individually distinctive and used as a contact call. We investigated the vocal behaviour of ten dolphins housed in three social groups at uShaka Sea World dolphinarium to determine how acoustic behavioural patterns link to dolphinarium routines. Investigation focused on overnight behaviour, housing decisions, weekly patterns, and transitional periods between presence and absence of husbandry staff. Recordings were made from 17h00 – 07h00 over 24 nights, spanning May to August 2018. Whistle production rate decreased soon after husbandry staff left the facility, was low over night, and increased upon arrival. Results indicated elevate arousal states associated with the morning arrival and presence of husbandry staff and heightened excitement associated with feeding. Housing in pool configurations which limited visual contact between certain groups were characterised by lower vocal production rates. Production of signature whistles was greater over the weekends compared to weekdays however total whistle production did not differ between weekends and weekdays. Heightened arousal associated with staff arrival was reflected in the structural characteristics of signature whistles, particularly maximum frequency, frequency range and number of whistle loops. Overall, these results revealed a link between scheduled activity and associated behavioural responses, which can be used as a baseline for future welfare monitoring where changes in normal behaviour may reflect shifts in welfare state.

scholarly journals Diversity, Distribution, and Density of Marine Mammals Along the Saudi Waters of the Arabian Gulf: Update From a Multi-Method Approach

2021 ◽  
Vol 8 ◽  
Author(s):  
Lotfi Rabaoui ◽  
Ruben H. Roa-Ureta ◽  
Lamia Yacoubi ◽  
Yu-Jia Lin ◽  
Rommel Maneja ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Oil And Gas ◽  
Bottlenose Dolphins ◽  
Arabian Gulf ◽  
Abundant Species ◽  
Common Species ◽  
Common Dolphin ◽  
Cetacean Species ◽  
Delphinus Delphis ◽  
Multi Method Approach

Despite the important role of marine mammals in marine ecosystems and the imperative for their conservation, there is still a great lack of information on the diversity, distribution, and density of these animals in the Saudi waters of the Arabian Gulf. To fill this gap, an integrative data-collection approach including fishermen’s questionnaires, opportunistic sighting reports, and directed boat-based surveys, was undertaken between 2016 and 2020, leading to the first scientific report of marine mammal diversity, distribution, and density in the region. The results of the different approaches carried out during the study confirmed a high diversity of cetaceans on the west coast of the study area, with bottlenose dolphins (Tursiops aduncus), humpback dolphins (Sousa plumbea) and dugongs (Dugong dugon) as the most common species. While the two dolphin species were found to be widely distributed in both coastal and offshore waters, D. dugon appears to occur exclusively in coastal waters in the southern part of the study area, mainly in the Gulf of Salwah. The presence of both species of dolphins increased during the summer months and in the vicinity of the numerous oil and gas facilities in this region. The distribution of the observed dolphins was found mostly within a 10–20 km radius around each facility. Other cetacean species observed less frequently in the area include Bryde’s whale (Balaenoptera edeni), killer whale (Orcinus orca), common dolphin (Delphinus delphis) and finless porpoise (Neophocaena phocaenoides). Regarding the density of marine mammals in the region, boat-based surveys confirmed the results of fishermen’s questionnaires and reports of opportunistic sightings, with bottlenose and humpback dolphins being the most abundant species. These results provide a baseline for policies oriented to the conservation of mammals in the Saudi waters of the Arabian Gulf.

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