A Note on Clicks Recorded from Free-Ranging Indo-Pacific Humpback Dolphins, Sousa chinensis

摘要

Opportunistic recordings of Indo-Pacific humpback dolphin clicks were made from a group of approximately ten humpback dolphins in the waters off Lantau Island, Hong Kong. Clicks were typically delphinid in waveshape, especially the click onsets, withspectral energy extending up to at least 200 kHz. Pulse durations were a few tens of microseconds. There appeared to be bimodal-ity in the click spectra, an observation consistent with the hypothesis of asymmetric phonating lips. Due to the opportunisticnature of the recordings and the uncontrolled recording conditions, click waveforms captured here are unlikely to be representative of on-axis signals, so the spectrum of the recorded signals may differ from those that would be recorded directly in front of the animals.