Whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China

Broadband recording systems were adapted to characterize the whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China. A total of 4630 whistles were recorded, of which 2651 with legible contours and relatively good signal-to-noise ratios were se...

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Published inThe Journal of the Acoustical Society of America Vol. 133; no. 4; p. 2479
Main Authors Wang, Zhitao, Fang, Liang, Shi, Wenjing, Wang, Kexiong, Wang, Ding
Format Journal Article
LanguageEnglish
Published United States 01.04.2013
Subjects
Acoustics
Animals
China
Dolphins - classification
Dolphins - physiology
Oceans and Seas
Signal Processing, Computer-Assisted
Signal-To-Noise Ratio
Singing
Sound Spectrography
Species Specificity
Swimming
Time Factors
Vocalization, Animal
China
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Summary:Broadband recording systems were adapted to characterize the whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China. A total of 4630 whistles were recorded, of which 2651 with legible contours and relatively good signal-to-noise ratios were selected for statistical analysis. Of the six tonal types (i.e., flat, down, rise, convex, U-shaped, and sine), flat (N = 1426; 39.45%) was the most predominant, followed by down (N = 754; 23.35%) and rise (N = 489; 12.34%). The whistles showed a short duration (mean ± SD: 370.19 ± 285.61 ms; range: 29-2923 ms), a broad frequency range (fundamental contour ranged from 0.52 to 33 kHz), and two harmonics (mean ± SD: 1.90 ± 2.74, with the maximum frequency of harmonics beyond 96 kHz). Whistles without gaps and stairs accounted for 76.7% and 86.4%, respectively. No significant interspecies differences in frequency parameters were observed compared with S. teuszii, which is inconsistent with morphological taxonomies but confirms phylogenetic results, thus suggesting a close relation between Chinese S. chinensis and Atlantic S. teuszii. Significant intra- and interspecific differences in the genus Sousa were also observed, indicating that animal vocalization may not be limited by genetically determined traits but could also be a function of local habitat adaptation.
ISSN:1520-8524
DOI:10.1121/1.4794390