Echolocation click parameters and biosonar behaviour of the dwarf sperm whale (<i>Kogia sima</i>)

ABSTRACT Dwarf sperm whales (Kogia sima) are small toothed that produce narrow-band high-frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, usually produced by small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range and fast click rates. Here, we sought address the problem how little-studied deep-diving Kogia can hunt clicks deep sea. Specifically, tested hypotheses longer inter-click intervals (ICIs), higher directionality source (SLs) compared other species. We did this deploying an autonomous deep-water vertical hydrophone array Bahamas, where no species present, taking opportunistic recordings a close-range sima South African harbour. Parameters from on-axis (n=46) revealed very (root mean squared bandwidth, BWRMS, 3±1 kHz), SLs up 197 dB re. 1 µPa peak-to-peak (μPapp) at m, half-power beamwidth 8.8 deg. Their ICIs (mode 245 ms) were much than those porpoises (&amp;lt;100 ms), suggesting inspection range is detection ranges single prey, perhaps facilitate auditory streaming complex echo scene. On-axis shallow harbour (n=870) had parameters cetaceans. Thus, deep, dwarf use directional, but system moderate SLs, reliable mesopelagic prey habitat.