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Preliminary evidence for signature vocalizations among free-ranging narwhals (Monodon monoceros)a)
a)Portions of this work were presented in “Vocal behavior of free-ranging Arctic narwhals (Monodon monoceros),” Proceedings of the 16th Biennial Conference on the Biology of Marine Mammals, San Diego, CA,December 2005.
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10.1121/1.2226586
/content/asa/journal/jasa/120/3/10.1121/1.2226586
http://aip.metastore.ingenta.com/content/asa/journal/jasa/120/3/10.1121/1.2226586

Figures

Image of FIG. 1.
FIG. 1.

Narwhal shown with Crittercam (contained within the dashed ellipse) and DTAG (contained within the dashed rectangle) attached immediately before release. Photograph courtesy of Rune Dietz.

Image of FIG. 2.
FIG. 2.

Sample spectrograms (larger, top plots) and waveforms (smaller, bottom plots) of a combined tonal/pulsed signal produced by individual (a) mm224 and (b) mm226 with a FFT size and frame length of 512 points, 50% window overlap, and a maximum frequency displayed of . The low frequency energy associated with most of the pulses is likely due to the resonance of the air sacs involved in sound production or transmission. The solid arrows in both spectrograms indicate the synchronous FM tonal component produced by the tagged animal.

Image of FIG. 3.
FIG. 3.

Spectrogram composite of all four whistles of mm224 (a–d) and 14 of the 17 whistles of mm226 (f–s) with a FFT size and frame length of 512 points, 50% window overlap, and a maximum frequency displayed of . The remaining 3 whistles of mm226 resembled those displayed here but were excluded for graphical convenience. The waveforms displayed in subplots e and t are of the same whistles used to generate subplots d and s, respectively.

Image of FIG. 4.
FIG. 4.

Digitized traces of the fundamental frequency contours of the whistles displayed in Fig. 3 . Each trace is shown with 100 equally spaced points that have been normalized on a horizontal time axis from 0 to 1. Again, panels a–d correspond to the whistles produced by mm224 and f–s to those by mm226. Note the difference in the frequency ranges for the two individuals.

Image of FIG. 5.
FIG. 5.

Illustration of temporal and spectral features extracted from a traced whistle produced by mm224 (subplot d in Figs. 3 and 4 ). The initial and ending frequencies are indicated by filled circles (●) while the other spectral components are marked with horizontal dashed lines. Note that the mean frequency is closer to the minimum frequency because of the whistle’s frequency content lies below .

Image of FIG. 6.
FIG. 6.

Illustration of points used for cross-correlation comparison of whistles (see text for the equation). In (a), contour (darker, from mm226: subplot i in Figs. 3 and 4 ) and (lighter, from mm224: subplot d in Figs. 3 and 4 ) are depicted normalized in time with their original frequency content. In (b), contour has been shifted along the frequency axis to minimize the frequency difference between the two contours. All 100 points along the contours were used to compute Eq. (1) .

Image of FIG. 7.
FIG. 7.

Approximate depths where combined tonal/pulsed signals (triangles, ▵) and whistles (circles, 엯) were produced adjacent to a frequency histogram of depth bins (bars) for mm224 (a) and mm226 (b). The frequency plotted on the abscissa is expressed as a fraction of the total amount of time spent at all depths. The maximum depths achieved for mm224 and mm226 during the DTAG deployments were roughly 125 and , respectively.

Image of FIG. 8.
FIG. 8.

Visual representations of temporal features of combined tonal/pulsed signals. Normalized pulse number (top two panels) and pulse repetition rate (pulses per second, bottom two panels) as a function of normalized duration. Note the clear differences in general morphology of these plots between the two individuals.

Tables

Generic image for table
TABLE I.

Summary statistics of the acoustic features of combined tonal/pulsed signals.

Generic image for table
TABLE II.

Summary statistics of the acoustic features of whistles.

Generic image for table
TABLE III.

Cross-correlation comparison of whistles between the same and different individuals. These data were computed in arbitrary units with higher values indicating a greater difference between the contours being compared. The intraindividual comparisons are italicized.

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/content/asa/journal/jasa/120/3/10.1121/1.2226586
2006-09-01
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Preliminary evidence for signature vocalizations among free-ranging narwhals (Monodon monoceros)a)
http://aip.metastore.ingenta.com/content/asa/journal/jasa/120/3/10.1121/1.2226586
10.1121/1.2226586
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