Dear Marmam,

here is a new publication on bottlenose dolphin echolocation click parameters from recordings from both the Atlantic and Australia.

Reprints are available from

Magnus Wahlberg, Magnus@fjord-baelt.dk

Abstract:

The Indian Ocean and Atlantic bottlenose dolphins (Tursiops aduncus and Tursiops truncatus) are

among the best studied echolocating toothed whales. However, almost all echolocation studies on

bottlenose dolphins have been made with captive animals, and the echolocation signals of freeranging

animals have not been quantified. Here, biosonar source parameters from wild T. aduncus

and T. truncatus were measured with linear three- and four-hydrophone arrays in four geographic

locations. The two species had similar source parameters, with source levels of 177–228 dB re

1 lPa peak to peak, click durations of 8–72 ls, centroid frequencies of 33–109 kHz and rms bandwidths

between 23 and 54 kHz. T. aduncus clicks had a higher frequency emphasis than T. truncatus.

The transmission directionality index was up to 3 dB higher for T. aduncus (29 dB) as compared to T.

truncatus (26 dB). The high directionality of T. aduncus does not appear to be only a physical consequence

of a higher frequency emphasis in clicks, but may also be caused by differences in the internal

properties of the sound production system.