Data from: Range-dependent flexibility in the acoustic field of view of echolocating porpoises (Phocoena phocoena)

Abstract

Toothed whales use sonar to detect, locate, and track prey. They adjust emitted sound intensity, auditory sensitivity and click rate to target range, and terminate prey pursuits with high-repetition-rate, low-intensity buzzes. However, their narrow acoustic field of view (FOV) is considered stable throughout target approach, which could facilitate prey escape at close-range. Here, we show that, like some bats, harbour porpoises can broaden their biosonar beam during the terminal phase of attack but, unlike bats, maintain the ability to change beamwidth within this phase. Based on video, MRI, and acoustic-tag recordings, we propose this flexibility is modulated by the melon and implemented to accommodate dynamic spatial relationships with prey and acoustic complexity of surroundings. Despite independent evolution and different means of sound generation and transmission, whales and bats adaptively change their FOV, suggesting that beamwidth flexibility has been an important driver in the evolution of echolocation for prey tracking.frame_hydro31102012a schematic showing the arrangement of individual hydrophones on the arrayframe more31102012an excel sheet linking the hydrophones id numbers to the channels in the recording systemdtag audio filedtag audio file for the 12th trial of the afternoon session on 31/10/2012, as well as matlab structures with outputs of click detectors, an echogram and an inter-click interval scatter plot (color-coded with relative apparent output level of the clicks)dtag.ziphydrophone relative calibration valuescalibration values (linear scale) of hydrophones relative to the hydrophone in the located in the centre of the array. each day a calibration was conducted to account for small differences int the array orientation or hydrophone placement between recording days. a short sweep was played from across the porpoise pool and recorded on all hydrophones. raw data available upon requestcalibrationValues.matfreja31102012_af12(ADpeak5.0V)_31-10-2012_14_01_52the folder contains recordings from 48 hydrophones, and manually verified detector data (matlab structures) from 21 of the hydrophones as well as combined click detector data (in sound_20121031_af12_50.mat