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First published online December 1, 2006
Journal of Experimental Biology 209, 5038-5050 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02596
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Foraging Blainville's beaked whales (Mesoplodon densirostris) produce distinct click types matched to different phases of echolocation

M. Johnson1,*, P. T. Madsen1,2, W. M. X. Zimmer3, N. Aguilar de Soto4 and P. L. Tyack1

1 Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
2 Department of Zoophysiology, University of Aarhus, Denmark
3 NATO Undersea Research Centre, V. le San Bartolomeo 400, 19126 La Spezia, Italy
4 Department of Animal Biology, La Laguna University, La Laguna 38206, Tenerife, Spain

* Author for correspondence (e-mail: majohnson{at}whoi.edu)

Accepted 16 October 2006

Blainville's beaked whales (Mesoplodon densirostris Blainville) echolocate for prey during deep foraging dives. Here we use acoustic tags to demonstrate that these whales, in contrast to other toothed whales studied, produce two distinct types of click sounds during different phases in biosonar-based foraging. Search clicks are emitted during foraging dives with inter-click intervals typically between 0.2 and 0.4 s. They have the distinctive form of an FM upsweep (modulation rate of about 110 kHz ms-1) with a -10 dB bandwidth from 26 to 51 kHz and a pulse length of 270 µs, somewhat similar to chirp signals in bats and Cuvier's beaked whales (Ziphius cavirostris Cuvier), but quite different from clicks of other toothed whales studied. In comparison, the buzz clicks, produced in short bursts during the final stage of prey capture, are short (105 µs) transients with no FM structure and a -10 dB bandwidth from 25 to 80 kHz or higher. Buzz clicks have properties similar to clicks reported from large delphinids and hold the potential for higher temporal resolution than the FM clicks. It is suggested that the two click types are adapted to the separate problems of target detection and classification versus capture of low target strength prey in a cluttered acoustic environment.

Key words: beaked whale, biosonar, echolocation, Mesoplodon densirostris, FM, sound production






© The Company of Biologists Ltd 2006