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  • 1
    Online Resource
    Online Resource
    Source parameters of echolocation clicks from wild bottlenose dolphins ( Tursiops aduncus and Tursiops truncatus )
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 130, No. 4 ( 2011-10-01), p. 2263-2274
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 130, No. 4 ( 2011-10-01), p. 2263-2274
    Abstract: The Indian Ocean and Atlantic bottlenose dolphins (Tursiops aduncus and Tursiops truncatus) are among the best studied echolocating toothed whales. However, almost all echolocation studies on bottlenose dolphins have been made with captive animals, and the echolocation signals of free-ranging animals have not been quantified. Here, biosonar source parameters from wild T. aduncus and T. truncatus were measured with linear three- and four-hydrophone arrays in four geographic locations. The two species had similar source parameters, with source levels of 177–228 dB re 1 μPa peak to peak, click durations of 8–72 μs, centroid frequencies of 33–109 kHz and rms bandwidths between 23 and 54 kHz. T. aduncus clicks had a higher frequency emphasis than T. truncatus. The transmission directionality index was up to 3 dB higher for T. aduncus (29 dB) as compared to T. truncatus (26 dB). The high directionality of T. aduncus does not appear to be only a physical consequence of a higher frequency emphasis in clicks, but may also be caused by differences in the internal properties of the sound production system.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3624822
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Comparison of echolocation clicks from geographically sympatric killer whales and long-finned pilot whales (L)
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 130, No. 1 ( 2011-07-01), p. 9-12
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 130, No. 1 ( 2011-07-01), p. 9-12
    Abstract: The source characteristics of biosonar signals from sympatric killer whales and long-finned pilot whales in a Norwegian fjord were compared. A total of 137 pilot whale and more than 2000 killer whale echolocation clicks were recorded using a linear four-hydrophone array. Of these, 20 pilot whale clicks and 28 killer whale clicks were categorized as being recorded on-axis. The clicks of pilot whales had a mean apparent source level of 196 dB re 1 μPa pp and those of killer whales 203 dB re 1 μPa pp. The duration of pilot whale clicks was significantly shorter (23 μs, S.E. = 1.3) and the centroid frequency significantly higher (55 kHz, S.E. = 2.1) than killer whale clicks (duration: 41 μs, S.E. = 2.6; centroid frequency: 32 kHz, S.E. = 1.5). The rate of increase in the accumulated energy as a function of time also differed between clicks from the two species. The differences in duration, frequency, and energy distribution may have a potential to allow for the distinction between pilot and killer whale clicks when using automated detection routines for acoustic monitoring.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3583499
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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  • 3
    Online Resource
    Online Resource
    Echolocation clicks from killer whales ( Orcinus orca ) feeding on herring ( Clupea harengus )
    Acoustical Society of America (ASA) ; 2007
    In:  The Journal of the Acoustical Society of America Vol. 121, No. 2 ( 2007-02-01), p. 749-752
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 121, No. 2 ( 2007-02-01), p. 749-752
    Abstract: Echolocation clicks from Norwegian killer whales feeding on herring schools were recorded using a four-hydrophone array. The clicks had broadband bimodal frequency spectra with low and high frequency peaks at 24 and 108kHz, respectively. The −10dB bandwidth was 35kHz. The average source level varied from 173to202dB re 1μPa (peak-to-peak) @ 1m. This is considerably lower than source levels described for Canadian killer whales foraging on salmon. It is suggested that biosonar clicks of Norwegian killer whales are adapted for localization of prey with high target strength and acute hearing abilities.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2404922
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2007
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  • 4
    Online Resource
    Online Resource
    Exploitation of sound during predator-prey interactions: Killer whales and herring
    Acoustical Society of America (ASA) ; 2006
    In:  The Journal of the Acoustical Society of America Vol. 119, No. 5_Supplement ( 2006-05-01), p. 3372-3372
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 119, No. 5_Supplement ( 2006-05-01), p. 3372-3372
    Abstract: The majority of killer whales (Orcinus orca) in Norway and Iceland feed cooperatively on schools of herring (Clupea harengus). The whales swim towards the school and, at short distances, perform underwater tail slaps that produce thudlike sounds containing impulses resembling cavitation pulses in duration, frequencies, and amplitude. Herring are debilitated by the underwater tail slaps, probably due to a combination of factors like sound pressure gradients, particle movements, hydrodynamic effects, and physical contact with the tail or other fish. Following the underwater tail slaps, killer whales can easily capture individual flaccid herring [Simon et al., J. Exp. Biol. 208, 2459–2466 (2005); a video will be shown]. Icelandic killer whales have another strategy not shown by their Norwegian relatives. A whale can emit a 3-s, 680-Hz call that ends 1 s before the tail slap. The frequency of the call falls within the herring audiogram, but outside that of killer whales. This call seems suited for herding the herring into tighter groups, making it possible to debilitate more fish [Simon et al., Behav. Ecol. Sociobiol. (submitted)] . Herring are not defenseless. The school can produce a flatulent bubble net that could hinder detection by killer whale biosonar [Wahlberg Westerberg, Aquatic Living Resources 16, 271–275 (2003)].
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4786570
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2006
    detail.hit.zdb_id: 1461063-2
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  • 5
    Online Resource
    Online Resource
    Acoustic characteristics of underwater tail slaps used by Norwegian and Icelandic killer whales ( Orcinus orca ) to debilitate herring( Clupea harengus )
    The Company of Biologists ; 2005
    In:  Journal of Experimental Biology Vol. 208, No. 12 ( 2005-06-15), p. 2459-2466
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 208, No. 12 ( 2005-06-15), p. 2459-2466
    Abstract: Norwegian killer whales debilitate prey by slapping their tails into herring schools. These underwater tail slaps produce a thud-like sound. It is unclear whether this sound is caused by cavitation and/or physical contact between herring and whale tail. Also the forces causing debilitation of the fish are not understood. Here we present an acoustic analysis of underwater tail slaps using a multi-channel wide (150 kHz) band recording system. Underwater tail slaps produced by Norwegian killer whales generated sounds consisting of multiple pulses with source levels of 186±5.4 dB (pp)re.1 μPa at 1 m (±1 s.d., N=4). The –3 dB and 97% energy bandwidths were 36.8±22.5 kHz and 130.5±17.5 kHz(±1 s.d., N=13), respectively, with a centre frequency of 46.1±22.3 kHz. The similarities between the acoustic properties of underwater tail slaps recorded from killer whales in Norway, and thud-like sounds recorded from killer whales in Iceland suggest that Norwegian and Icelandic killer whales use similar hunting techniques. The acoustic characteristics of sounds produced by underwater tail slaps were similar to the ones from other cavitation sound sources described in the literature, both in term of temporal and frequency features as well as in source level. We suggest that multiple factors generated by the tail slaps like particle fluctuations, turbulence, pressure changes and physical impact cause debilitation of herring.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.01619
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2005
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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