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

• Published in: The Journal of the Acoustical Society of America 2021-03, Vol.149 (3), p.1923-1931
• Main Authors: Pedersen, M. B., Tønnesen, P., Malinka, C. E., Ladegaard, M., Johnson, M., Aguilar de Soto, N., Madsen, P. T.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/10.0003762

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.