The Journal of the Acoustical Society of America
Acoustic, Whistles, sousa chinensis, humpback dolphins, China, Vocalization
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, Ushaped, and sine), flat (N¼1426; 39.45%) was the most predominant, followed by down (N¼754; 23.35%) and rise (N¼489; 12.34%). The whistles showed a short duration (mean6SD: 370.196285.61 ms; range: 29–2923 ms), a broad frequency range (fundamental contour ranged from 0.52 to 33 kHz), and two harmonics (mean6SD: 1.9062.74, 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.