|Title||Foraging Blainville's beaked whales (Mesoplodon densirostris) produce distinct click types matched to different phases of echolocation|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Johnson, M., Madsen P. T., Zimmer W. M. X., de Soto N. A., and Tyack P. L.|
|Journal||Journal of Experimental Biology|
|EndNote Rec Number||934|
|Keywords||beaked whale, big brown bats, biosonar, echolocation, eptesicus-fuscus, fm, Mesoplodon densirostris, pipistrelle bats, prey capture, pseudorca-crassidens, pulse compression, signals, sound production, target range, transmission beam pattern, tursiops-truncatus montagu|
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 110kHz ms(-1)) with a-10 dB bandwidth from 26 to 51kHz and a pulse length of 270 mu s, 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 mu s) transients with no FM structure and a -10dB bandwidth from 25 to 80kHz 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.