Echolocation click parameters of short-finned pilot whales ( Globicephala macrorhynchus ) in the wild

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Pedersen, M. B., Tønnesen, P., Malinka, C. E., Ladegaard, M., Johnson, M., Aguilar de Soto, N., Madsen, P. T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: toothed whale
• Online Access: https://pure.au.dk/portal/en/publications/63ee7a27-96f6-4fe1-9d52-df1079eeefad; https://doi.org/10.1121/10.0003762; http://www.scopus.com/inward/record.url?scp=85102864531&partnerID=8YFLogxK

Short-finned pilot whales (Globicephala macrorhynchus) are large, deep-diving predators with diverse foraging strategies, but little is known about their echolocation. To quantify the source properties of short-finned pilot whale clicks, we made 15 deployments off the coast of Tenerife of a deep-water hydrophone array consisting of seven autonomous time-synced hydrophone recorders (SoundTraps), enabling acoustic localization and quantification of click source parameters. Of 8185 recorded pilot whale clicks, 47 were classified as being recorded on-axis, with a mean peak-to-peak source level (SL) of 181 ± 7 dB re 1 μPa, a centroid frequency of 40 ± 4 kHz, and a duration of 57 ± 23 μs. A fit to a piston model yielded an estimated half-power (-3 dB) beam width of 13.7° [95% confidence interval (CI) 13.2°-14.5°] and a mean directivity index (DI) of 22.6 dB (95% CI 22.5-22.9 dB). These measured SLs and DIs are surprisingly low for a deep-diving toothed whale, suggesting we sampled the short-finned pilot whales in a context with little need for operating a long-range biosonar. The substantial spectral overlap with beaked whale clicks emitted in similar deep-water habitats implies that pilot whale clicks may constitute a common source of false detections in beaked whale passive acoustic monitoring efforts.