Abstract
Recordings were made from a group of Risso's dolphins (Grampus griseus) off the coast of Newcastle, Australia, between 30 Hz and 22 kHz. Risso's dolphins exhibited seven separate vocalisation types: broadband clicks, barks, buzzes, grunts, chirps, whistles, and simultaneous whistle + burst-pulse sounds. Broadband clicks were highly variable in duration, with a frequency range of 6 to >22 kHz. Bark vocalisations consisted of highly variable burst pulses, with durations ranging from 0.2 to 7.4 s and a frequency range of 2-20 kHz. Buzz vocalisations were clearly stereotyped, consisting of a short burst pulse of around 2 s and a frequency range of 2.1 to >22 kHz. Low frequency narrowband grunt vocalisations (0.40.8 kHz) were short in duration. Chirp vocalisations were slightly higher in frequency than the grunt vocalisations, ranging in frequency from 2 to 4 kHz. There were at least five different whistle types, ranging in frequency from 4 to 22 kHz. We recorded a combined tonal and burst-pulse vocalisation. The rising whistles ranged from 6 to 18 kHz, while the burst-pulse sounds ranged between 3 and 21 kHz. This combined whistle + burst pulse sound appears to be unique to Risso's dolphins.
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