Special section on biologically-inspired radar and sonar systems - Review of the occurrence of multiple pulse echolocation clicks in recordings from small odontocetes

This study investigates the extent of the possible correlation between small odontocetes that predominantly inhabit littoral waters, and those which have been associated with the detection of echolocation clicks that consist of multiple pulses. The echolocation clicks discussed are primarily characterised as short, high frequency (>;100>;kHz) and narrow band. There are many sources that report clicks that contain multiple pulses and there is more than one structure associated with such pulses. A review of the literature provides a list of odontocetes which have been associated with such sounds and the structure of those reported clicks. The competing hypotheses regarding the origins of such multiple pulses in recordings are discussed. Regardless of the mechanism by which multiple pulse clicks occur, there are potential competitive advantages which may arise from them, and these are highlighted.