Time sequences of sonar signals generated by a beluga whale when locating underwater objects

Rutenko, A. N.; Vishnyakov, A. A.

doi:10.1134/s1063771006030122

“…Additionally, the lower frequency content observed in narwhal echolocation may indicate that narwhals have a longer echolocation detection range for prey and PAM receivers than belugas. Previous work to quantify beluga echolocation parameters reveals high variability and evidence of biosonar adaptability 16 , 36 , 37 , 40 , 79 . For example, estimates of beluga echolocation peak frequencies range widely between 40–120 kHz across captive and wild environments 34 , 36 – 38 , 40 , 79 and have been shown to change depending on the ambient sound levels of the environment 36 .…”

Section: Discussionmentioning

confidence: 99%

“…Previous work to quantify beluga echolocation parameters reveals high variability and evidence of biosonar adaptability 16 , 36 , 37 , 40 , 79 . For example, estimates of beluga echolocation peak frequencies range widely between 40–120 kHz across captive and wild environments 34 , 36 – 38 , 40 , 79 and have been shown to change depending on the ambient sound levels of the environment 36 . Narwhal echolocation has been largely characterized by lower frequency clicks with maxima between 30–70 kHz 30 , 32 , 43 , 44 , but high-frequency clicks have been reported where the entire bandwidth can extend up to 200 kHz 25 .…”

Section: Discussionmentioning

confidence: 99%

“…However, their comparison was narrow in scope as it was not their primary research objective. Thorough analyses of echolocation clicks have been conducted separately on belugas 21 , 36 – 40 and narwhals 25 , 27 , 41 , 42 , but no comparative study with data from the same region exists. The broadband signals of beluga and narwhal echolocation extend frequencies between 2–150 kHz, but high-frequency clicks have been reported for both species with energies up to 200 kHz 25 , 39 .…”

Section: Introductionmentioning

confidence: 99%

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Acoustic differentiation and classification of wild belugas and narwhals using echolocation clicks

Zahn

¹

,

Rankin

²

,

McCullough

³

et al. 2021

Sci Rep

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Belugas (Delphinapterus leucas) and narwhals (Monodon monoceros) are highly social Arctic toothed whales with large vocal repertoires and similar acoustic profiles. Passive Acoustic Monitoring (PAM) that uses multiple hydrophones over large spatiotemporal scales has been a primary method to study their populations, particularly in response to rapid climate change and increasing underwater noise. This study marks the first acoustic comparison between wild belugas and narwhals from the same location and reveals that they can be acoustically differentiated and classified solely by echolocation clicks. Acoustic recordings were made in the pack ice of Baffin Bay, West Greenland, during 2013. Multivariate analyses and Random Forests classification models were applied to eighty-one single-species acoustic events comprised of numerous echolocation clicks. Results demonstrate a significant difference between species’ acoustic parameters where beluga echolocation was distinguished by higher frequency content, evidenced by higher peak frequencies, center frequencies, and frequency minimums and maximums. Spectral peaks, troughs, and center frequencies for beluga clicks were generally > 60 kHz and narwhal clicks < 60 kHz with overlap between 40–60 kHz. Classification model predictive performance was strong with an overall correct classification rate of 97.5% for the best model. The most important predictors for species assignment were defined by peaks and notches in frequency spectra. Our results provide strong support for the use of echolocation in PAM efforts to differentiate belugas and narwhals acoustically.

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“…Additionally, the lower frequency content observed in narwhal echolocation may indicate that narwhals have a longer echolocation detection range for prey and PAM receivers than belugas. Previous work to quantify beluga echolocation parameters reveals high variability and evidence of biosonar adaptability 16,36,37,40,79 . For example, estimates of beluga echolocation peak frequencies range widely between 40-120 kHz across captive and wild environments 34,[36][37][38]40,79 and have been shown to change depending on the ambient sound levels of the environment 36 .…”

Section: Discussionmentioning

confidence: 99%

“…Previous work to quantify beluga echolocation parameters reveals high variability and evidence of biosonar adaptability 16,36,37,40,79 . For example, estimates of beluga echolocation peak frequencies range widely between 40-120 kHz across captive and wild environments 34,[36][37][38]40,79 and have been shown to change depending on the ambient sound levels of the environment 36 . Narwhal echolocation has been largely characterized by lower frequency clicks with maxima between 30-70 kHz 30,32,43,44 , but high-frequency clicks have been reported where the entire bandwidth can extend up to 200 kHz 25 .…”

Section: Discussionmentioning

confidence: 99%

Acoustic differentiation and classification of wild belugas and narwhals using echolocation clicks

Zahn

¹

,

Rankin

²

,

McCullough

³

et al. 2021

The Journal of the Acoustical Society of America

0

View full text Add to dashboard Cite

Belugas (Delphinapterus leucas) and narwhals (Monodon monoceros) are highly social Arctic toothed whales with large vocal repertoires and similar acoustic profiles. Passive Acoustic Monitoring (PAM) that uses multiple hydrophones over large spatiotemporal scales has been a primary method to study their populations, particularly in response to rapid climate change and increasing underwater noise. This study marks the first acoustic comparison between wild belugas and narwhals from the same location and reveals that they can be acoustically differentiated and classified solely by echolocation clicks. Acoustic recordings were made in the pack ice of Baffin Bay, West Greenland, during 2013. Multivariate analyses and Random Forests classification models were applied to eighty-one singlespecies acoustic events comprised of numerous echolocation clicks. Results demonstrate a significant difference between species' acoustic parameters where beluga echolocation was distinguished by higher frequency content, evidenced by higher peak frequencies, center frequencies, and frequency minimums and maximums. Spectral peaks, troughs, and center frequencies for beluga clicks were generally > 60 kHz and narwhal clicks < 60 kHz with overlap between 40-60 kHz. Classification model predictive performance was strong with an overall correct classification rate of 97.5% for the best model. The most important predictors for species assignment were defined by peaks and notches in frequency spectra. Our results provide strong support for the use of echolocation in PAM efforts to differentiate belugas and narwhals acoustically.Only three species of cetaceans occupy the Arctic year-round: the beluga (Delphinapterus leucas), narwhal (Monodon monoceros), and bowhead whale (Balaena mysticetus). As toothed whales (odontocetes), the beluga and narwhal are closely related and are the only two members of the Monodontidae family. They use echolocation to identify objects and locate prey, unlike the bowhead whale, a baleen whale, that has not evolved this sense 1,2 . Belugas are circumpolar in their distribution with approximately 22 subpopulations, or stocks, some of which are highly migratory and others resident in both Arctic and sub-Arctic waters [3][4][5][6][7][8][9] . Most populations migrate from wintering regions among the pack ice and return to the same estuarine summering areas to feed, molt, and give birth 8,10,11 . In contrast, narwhals occur in approximately 12 stocks and have a more restricted distribution occupying waters of the Canadian Arctic, West and East Greenland, and western Russia within the Atlantic Arctic [12][13][14] . Narwhals in the Canadian Arctic and West Greenland undergo extensive annual migrations with high site fidelity from their summer ranges in fjords of Greenland and Baffin Island to their wintering grounds in Baffin Bay and northern Davis Strait 3,13,15 . Across their respective distributions, belugas and most of the world's narwhals overlap for much of the year in the waters of the Canadian Arctic and Baffin Bay,...

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