Discriminating between the clicks produced by a bottlenose dolphin when searching for and identifying an object during a search task

Abstract

Clicks collected from an echolocating bottlenose dolphin completing a search task were compared in order to determine if the clicks produced when the dolphin was acquiring the target differed from the clicks produced when the dolphin was searching for the target. The clicks produced by a free-swimming dolphin completing the search task were recorded using a biosonar measurement tool (BMT), an instrumentation package carried by the dolphin that collected both the outgoing clicks and the returning echoes. A discriminant function analysis classified the clicks as search or acquisition using the variables of peak-to-peak amplitude, duration, peak frequency, center frequency, and bandwidth. The acquisition clicks were classified more accurately than the search clicks. Acquisition clicks and search clicks were significantly different across all five of the variables. These results suggest that the clicks produced by bottlenose dolphins acquiring a target are different than those produced by dolphins searching for a target.