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1.
Sci Rep ; 11(1): 21195, 2021 11 11.
Article in English | MEDLINE | ID: mdl-34764300

ABSTRACT

Vessel noise is a primary driver of behavioural disturbance in cetaceans, which are targeted during whale-watch activities. Despite the growing, global effort for implementing best-practice principles, to date, there are no regulations on whale-watch vessel noise levels. Here, we test the hypothesis that a whale-watch vessel with a low noise emission will not elicit short-term behavioural responses in toothed whales compared to a vessel with a louder engine. We measured behavioural responses (n = 36) of short-finned pilot whales (Globicephala macrorhynchus) to whale-watch vessel approaches (range 60 m, speed 1.5 kn). Treatment approaches with a quieter electric engine (136-140 dB) compared to the same vessel with a louder petrol engine (151-139 dB) (low-frequency-mid-frequency weighted source levels, re 1 µPa RMS @ 1 m) were examined. Focal whales were resting mother and calves in small group sizes. During petrol engine treatments, the mother's mean resting time decreased by 29% compared to the control (GLM, p = 0.009). The mean proportion of time nursing for the calf was significantly influenced by petrol engine vessel passes, with a 81% decrease compared to the control (GLM, p = 0.01). There were no significant effects on behaviour from the quieter electric engine. Thus, to minimise disturbance on the activity budget of pilot whales, whale-watch vessels would ideally have source levels as low as possible, below 150 dB re 1 µPa RMS @ 1 m and perceived above ambient noise.


Subject(s)
Noise/adverse effects , Whales, Pilot/psychology , Acoustics , Animals
2.
J Exp Biol ; 221(Pt 11)2018 06 12.
Article in English | MEDLINE | ID: mdl-29895580

ABSTRACT

The risk of predation is often invoked as an important factor influencing the evolution of social organization in cetaceans, but little direct information is available about how these aquatic mammals respond to predators or other perceived threats. We used controlled playback experiments to examine the behavioral responses of short-finned pilot whales (Globicephala macrorhynchus) off Cape Hatteras, NC, USA, and Risso's dolphins (Grampus griseus) off the coast of Southern California, USA, to the calls of a potential predator, mammal-eating killer whales. We transmitted calls of mammal-eating killer whales, conspecifics and baleen whales to 10 pilot whales and four Risso's dolphins equipped with multi-sensor archival acoustic recording tags (DTAGs). Only playbacks of killer whale calls resulted in significant changes in tagged animal heading. The strong responses observed in both species occurred only following exposure to a subset of killer whale calls, all of which contained multiple non-linear properties. This finding suggests that these structural features of killer whale calls convey information about predatory risk to pilot whales and Risso's dolphins. The observed responses differed between the two species; pilot whales approached the sound source while Risso's dolphins fled following playbacks. These divergent responses likely reflect differences in anti-predator response mediated by the social structure of the two species.


Subject(s)
Dolphins/psychology , Vocalization, Animal , Animals , Atlantic Ocean , North Carolina , Social Behavior , Species Specificity , Whale, Killer/psychology , Whales, Pilot/psychology
3.
J Acoust Soc Am ; 141(6): 4289, 2017 06.
Article in English | MEDLINE | ID: mdl-28618811

ABSTRACT

The knowledge of the vocal repertoire of pilot whales is very limited. In this paper, the vocal repertoire of long-finned pilot whales recorded during different encounters in the Vestfjord in northern Norway between November 2006 and August 2010 are described. Sounds were analysed using two different methods: (1) an observer-based audio-visual inspection of FFT-derived spectrograms, with which, besides a general variety of clicks, buzzes, nonharmonic sounds, and whistles, 129 different distinct call types and 25 subtypes were distinguished. These call types included pulsed calls and discrete structured whistles varying from simple to highly complex structures composed of several segments and elements. In addition, ultrasonic whistles previously not described for pilot whales were found. In addition to the diversity of single calls, call sequences consisting of repetitions and combinations of specific call types were recorded and (2) a parametric approach that permitted the confirmation of the high variability in pilot whale call structures was developed. It is concluded that the pilot whale vocal repertoire is among the most complex for the mammalian species and the high structural variability, along with call repetitions and combinations, require a closer investigation to judge their importance for vocal communication.


Subject(s)
Acoustics , Echolocation , Vocalization, Animal/classification , Whales, Pilot/classification , Whales, Pilot/psychology , Animals , Judgment , Norway , Signal Processing, Computer-Assisted , Sound Spectrography , Species Specificity , Visual Perception
4.
J Acoust Soc Am ; 135(2): 953-62, 2014 Feb.
Article in English | MEDLINE | ID: mdl-25234903

ABSTRACT

Vocal communication is a primary communication method of killer and pilot whales, and is used for transmitting a broad range of messages and information for short and long distance. The large variation in call types of these species makes it challenging to categorize them. In this study, sounds recorded by audio sensors carried by ten killer whales and eight pilot whales close to the coasts of Norway, Iceland, and the Bahamas were analyzed using computer methods and citizen scientists as part of the Whale FM project. Results show that the computer analysis automatically separated the killer whales into Icelandic and Norwegian whales, and the pilot whales were separated into Norwegian long-finned and Bahamas short-finned pilot whales, showing that at least some whales from these two locations have different acoustic repertoires that can be sensed by the computer analysis. The citizen science analysis was also able to separate the whales to locations by their sounds, but the separation was somewhat less accurate compared to the computer method.


Subject(s)
Artificial Intelligence , Crowdsourcing , Data Mining/methods , Databases, Factual/classification , Vocalization, Animal , Whale, Killer/physiology , Whales, Pilot/physiology , Acoustics , Animals , Ecosystem , Motion , Pattern Recognition, Automated , Signal Processing, Computer-Assisted , Sound , Sound Spectrography , Species Specificity , Time Factors , Whale, Killer/classification , Whale, Killer/psychology , Whales, Pilot/classification , Whales, Pilot/psychology
5.
Mar Pollut Bull ; 83(1): 165-80, 2014 Jun 15.
Article in English | MEDLINE | ID: mdl-24820645

ABSTRACT

The potential effects of exposing marine mammals to military sonar is a current concern. Dose-response relationships are useful for predicting potential environmental impacts of specific operations. To reveal behavioral response thresholds of exposure to sonar, we conducted 18 exposure/control approaches to 6 long-finned pilot whales. Source level and proximity of sonar transmitting one of two frequency bands (1-2 kHz and 6-7 kHz) were increased during exposure sessions. The 2-dimensional movement tracks were analyzed using a changepoint method to identify the avoidance response thresholds which were used to estimate dose-response relationships. No support for an effect of sonar frequency or previous exposures on the probability of response was found. Estimated response thresholds at which 50% of population show avoidance (SPLmax=170 dB re 1 µPa, SELcum=173 dB re 1 µPa(2) s) were higher than previously found for other cetaceans. The US Navy currently uses a generic dose-response relationship to predict the responses of cetaceans to naval active sonar, which has been found to underestimate behavioural impacts on killer whales and beaked whales. The navy curve appears to match more closely our results with long-finned pilot whales, though it might underestimate the probability of avoidance for pilot-whales at long distances from sonar sources.


Subject(s)
Behavior, Animal/radiation effects , Noise/adverse effects , Whales, Pilot/psychology , Animals , Dose-Response Relationship, Radiation
6.
J Acoust Soc Am ; 135(1): 502-12, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24437790

ABSTRACT

Acoustic observation can complement visual observation to more effectively monitor occurrence and distribution of marine mammals. For effective acoustic censuses, calibration methods must be determined by joint visual and acoustic studies. Research is still needed in the field of acoustic species identification, particularly for smaller odontocetes. From 1994 to 2012, whistles of four odontocete species were recorded in different areas of the Mediterranean Sea to determine how reliably these vocalizations can be classified to species. Recordings were attributed to species by simultaneous visual observation. The results of this study highlight that the frequency parameters, which are linked to physical features of animals, show lower variability than modulation parameters, which are likely to be more dependent on complex eco-ethological contexts. For all the studied species, minimum and maximum frequencies were linearly correlated with body size. DFA and Classification Tree Analysis (CART) show that these parameters were the most important for classifying species; however, both statistical methods highlighted the need for combining them with the number of contour minima and contour maxima for correct classification. Generally, DFA and CART results reflected both phylogenetic distance (especially for common and striped dolphins) and the size of the species.


Subject(s)
Acoustics , Dolphins/psychology , Environmental Monitoring/methods , Vocalization, Animal , Animals , Body Size , Bottle-Nosed Dolphin/classification , Bottle-Nosed Dolphin/physiology , Bottle-Nosed Dolphin/psychology , Common Dolphins/classification , Common Dolphins/physiology , Common Dolphins/psychology , Decision Trees , Dolphins/classification , Dolphins/physiology , Humans , Linear Models , Mediterranean Sea , Models, Statistical , Reproducibility of Results , Signal Processing, Computer-Assisted , Sound Spectrography , Species Specificity , Stenella/classification , Stenella/physiology , Stenella/psychology , Visual Perception , Whales, Pilot/classification , Whales, Pilot/physiology , Whales, Pilot/psychology
7.
J Acoust Soc Am ; 135(1): 531-6, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24437793

ABSTRACT

On May 5, 2011, 23 short-finned pilot whales, Globicephala macrorhynchus, were stranded along the coastline near Cudjoe Key, FL. Five animals (two adult females, two juvenile females, and an adult male) were transported to a rehabilitation facility in Key Largo, FL. Auditory evoked potentials (AEPs) were recorded in response to amplitude modulated tone pips modulated at 1000 Hz. AEP thresholds were determined at 10, 20, 40, 80, and 120 kHz for the four females. However, the adult male was euthanized prior to testing. Short-finned pilot whales had peak sensitivity at lower frequencies than other odontocetes such as bottlenose dolphins. Greatest sensitivity was around 40 kHz for all whales, while thresholds for the two adult females were 25-61 dB higher at 80 kHz than the juveniles. Click evoked potentials were similar between the four whales and comparable to other echolocating odontocetes. Click evoked potential data from a fifth short-finned pilot whale that had stranded in Curacao showed no response. These findings add to the limited database of pilot whale (short- and long-finned) hearing studies, of which there are only two others [Schlundt et al. (2011). J. Acoust. Soc. Am. 129, 1111-1116 and Pacini et al. (2010). J. Exp. Biol. 213, 3138-3143].


Subject(s)
Auditory Threshold , Whales, Pilot/psychology , Acoustic Stimulation , Age Factors , Animals , Electroencephalography , Evoked Potentials, Auditory , Female , Fourier Analysis , Hearing Tests , Male , Sex Factors , Time Factors , Whales, Pilot/classification , Whales, Pilot/physiology
8.
Behav Processes ; 91(1): 8-14, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22561079

ABSTRACT

Synchronized swimming in cetaceans has been hypothesized to play a role in affiliative processes as well as anti-predatory responses. We compared observed variation in synchronized swimming at two research sites in relation to disturbance exposure to test these two hypotheses. This study describes and quantifies pair synchronization in long-finned pilot whales at the Strait of Gibraltar, Spain and Cape Breton, Canada. Synchronization differed depending on the behavioral state and the response is different in the two sites leading to the conclusion that environment can shape the occurrence and magnitude of certain behaviors. We also analyzed intra-population variations in synchronization among 4 social units of Pilot whales in the Strait of Gibraltar and the results of this study confirmed the affiliative role of synchronization and highlighted an influence of disturbance on synchronization. We can conclude that synchronization is a common behavior in long-finned pilot whales that allow for close proximity and rapid coordinated response of individuals, with the multiple functions of showing affiliation and reacting to disturbance.


Subject(s)
Predatory Behavior , Social Behavior , Swimming/psychology , Whales, Pilot/psychology , Animals , Canada , Spain , Video Recording/methods
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