Echolocation signals of dusky dolphins (Lagenorhynchus obscurus) in Kaikoura, New Zealand

Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1109, Kailua, Hawaii 96734, USA.
The Journal of the Acoustical Society of America (Impact Factor: 1.5). 06/2004; 115(5 Pt 1):2307-13. DOI: 10.1121/1.1690082
Source: PubMed

ABSTRACT An array of four hydrophones arranged in a symmetrical star configuration was used to measure the echolocation signals of the dusky dolphin (Lagenorhynchus obscurus) near the Kaikoura Peninsula, New Zealand. Most of the echolocation signals had bi-modal frequency spectra with a low-frequency peak between 40 and 50 kHz and a high-frequency peak between 80 and 110 kHz. The low-frequency peak was dominant when the source level was low and the high frequency peak dominated when the source level was high. The center frequencies in the dusky broadband echolocation signals are among the highest of dolphins measured in the field. Peak-to-peak source levels as high as 210 dB re 1 microPa were measured, although the average was much lower in value. The levels of the echolocation signals are about 9-12 dB lower than for the larger white-beaked dolphin (Lagenorhynchus albirostris) which belongs to the same genus but is over twice as heavy as the dusky dolphins. The source level varied in amplitude approximately as a function of the one-way transmission loss for signals traveling from the animals to the array. The wave form and spectrum of the echolocation signals were similar to those of other dolphins measured in the field.

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    • "Consequently, the porpoises are attacked by Killer Whales during their social communications (Szymanski et al., 1999). However, if the depredator uses low frequency echolocation for detecting fishes, the porpoises can detect Killer Whales (Au et al., 2004). Finally, the third group with the high Doppler effect is formed by certain species of the Ziphidae family, particularly the genus Mesoplodon, Indopacetus pacificus and Ziphius cavirostris. "
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    ABSTRACT: Cetaceans are widely diversified in their sonometric characteristics but no comparative research has determined the general patterns that condition their bio-acoustic evolution across a large number of species. Echolocation calls of 69 cetaceans species has been obtained from different data sources. Through analysis by a Hierarchical Partitioning test, a non-parametric substitute of variance analysis, the absence of statistical differences between bioacoustic data sources has been demonstrated. Sounds were normalized and the fundamental frequency of each species was determined by autocorrelation. Also, the average swimming speed of each species was obtained from published papers. Finally, the intensity of the Doppler effect was calculated for each species using the mathematical equation of underwater sound physics. Doppler shifts lower than 160 Hz were found for the majority of species. This can be explained as a behavioral strategy to avoid depredation by Killer Whales. Only certain species of Ziphidae (genus Mesoplodon, Indopacetus pacificus and Ziphius cavirostris) and six species of Delphinidae (from Lagenorhynchus and Cephalorhynchus genus) present higher Doppler shifts. These species had found other strategies to avoid depredation such as the use of echolocation only in deep waters, very high average swimming speeds, large flocks or the use of very high frequencies. From these results it is possible to conclude that depredation conditions all the evolution of echolocation signals of cetaceans except in a reduced number of species that had developed different behavioral strategies to escape from Killer Whales.
    Journal of Experimental Marine Biology and Ecology 06/2014; 455:50-55. DOI:10.1016/j.jembe.2014.02.016 · 1.87 Impact Factor
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    • "The measurements of the scattering layer off Hawaii in the present study were also quite similar to those taken at the same locations in previous work ( Benoit - Bird & Au 2003a ) . Mean scattering , maximum scatter - ing , and variance in scattering were all similar in their distribution to those measured previously at various times of the year encompassing all ' seasons ' ( Benoit - Bird & Au 2003a , b , 2004a , 2006 ) . While migration tim - ing is similar relative to sunset and sunrise in all stud - ies ( as in the New Zealand data ) unlike off New Zealand , the duration of scattering layer presence also changed little throughout the year off Hawaii . "
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    ABSTRACT: Many delphinids feed on vertically migrating sound-scattering layers. The migration of micronektonic animals in these layers is strongly affected by light, both solar and lunar. Active acoustic approaches were used to observe lunar phase effects on the diel patterns of sound-scattering layers in 2 habitats and to simultaneously observe the behavior of foraging spinner dolphins Stenella longirostris in Hawaii and dusky dolphins Lagenorhynchus obscurus in New Zealand. Lunar phase was important in structuring the behavior of diurnally migrating animals in scattering layers off both New Zealand and Hawaii. While the responses of these scattering layers to lunar phase differed between locations, the layers were similar in continuing to migrate to surface waters during all moon phases, in contrast to results from other locations. In both dusky and spinner dolphins, dolphin relative abundance increased with increasing lunar illumination. The dolphin response to lunar phase is not clearly explained by the observed changes in prey. However, the results suggest that lunar phase is likely to be important in driving behavior of the many delphinid species that forage on vertically migrating prey. Active acoustics can be used to simultaneously study predator and prey, elucidating the foraging behavior of other dolphin species feeding on sound-scattering layers. Comparing the observed patterns to the phylogeny of these diverse species could provide insights into the evolution of behavior in delphinids.
    Marine Ecology Progress Series 12/2009; 395:119-135. DOI:10.3354/meps07793 · 2.62 Impact Factor
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    • "Extensive research has been conducted on bottlenose dolphins since 1970 in Sarasota, United-States (Irvine and Wells 1972) and since 1984 in Shark Bay, Australia (Connor and Smolker 1985). The deep near-shore waters off Kaikoura, New Zealand, has offered an ideal opportunity to study the behaviour and ecology of males sperm whales (Physeter macrocephalus) (Childerhouse et al. 1995) and other marine mammals (e.g., dusky dolphins, Lagenorhynchus obscurus, Au and Wursig 2004; southern right-whale dolphins, Lissodelphis peronii, Visser et al. 2004). These studies of cetaceans in near-shore areas have provided key insights about cetacean behaviour, which have contributed to major advances over the last several decades in the behavioural ecology of marine mammal foraging, parental care, and social organization (Connor et al. 1992; Ford et al. 1998; Mann and Smuts 1999). "
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    ABSTRACT: The narwhal (Monodon monoceros) is a deep diving cetacean with a strictly Arctic distribution. The challenges associated with the remoteness of narwhals have resulted in a lack of knowledge of its social behaviour requiring direct, systematic observations. Bruce Head, a peninsula at the mouth of Koluktoo Bay (Nunavut), provides an exceptional site in Canada for nearshore observation of narwhals during the summer. In this study, we document the movement, timing and grouping patterns of narwhals observed from Bruce Head and how they relate to environmental factors such as the tide and the circadian cycle. Narwhals travelled in clusters of 1–25 individuals of mixed sex and age class. Narwhals entered the bay in bigger clusters than when they exited it. The clusters were part of herds that comprised up to 642 clusters. Narwhal movement patterns were not randomly distributed in time but did not consistently follow the tidal or circadian cycles across years. Bruce Head could host long-term behavioural studies of narwhals to unravel several unanswered aspects of narwhal biology.
    Polar Biology 12/2009; 32(12):1705-1716. DOI:10.1007/s00300-009-0670-x · 1.59 Impact Factor
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