Dear MARMAM community,
We’d like to let you know about a new publication in JEB on the bioacoustic of dwarf sperm whales:
Malinka CE, Tønnesen P, Dunn C, Claridge D, Gridley T, Elwen SH, & PT Madsen. (2021). “Echolocation click parameters and acoustic behaviour of wild dwarf sperm whale (Kogia sima),”
The Journal of Experimental Biology, 224(6): jeb240689. doi:
10.1242/jeb.240689.
Abstract: Dwarf sperm whales (Kogia sima) are small toothed whales that produce narrow band high frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, are usually produced by
small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range echolocation and fast click rates. Here we sought to address the problem of how the little-studied and deep-diving Kogia can hunt with NBHF clicks in the deep sea. Specifically,
we tested the hypotheses that Kogia produce NBHF clicks with longer inter-click intervals (ICIs), higher directionality, and higher source levels (SLs) compared to other NBHF species. We did this by deploying an autonomous deep-water vertical hydrophone array
in the Bahamas, where no other NBHF species are present, and by taking opportunistic recordings of a close-range Kogia sima in a South African harbour. Parameters from on-axis clicks (n=46) in the deep revealed very narrowband clicks (BWRMS
of 3 + 1 kHz), with SLs of up to 197 dB re 1 µPapp @ 1 m, and a half-power beamwidth of 8.8°. Their ICIs (mode of 245 ms) are much longer than porpoises (<100 ms), suggesting an inspection range that is longer than detection ranges of single
prey, perhaps to facilitate auditory streaming of a complex echo scene. On-axis clicks in the shallow harbour (n=870) had ICIs and SLs in keeping with source parameters of other NBHF cetaceans. Thus, in the deep, dwarf sperm whales use a directional, but short-range
echolocation system with moderate SLs, suggesting a reliable mesopelagic prey habitat.
The PDF is also freely available on the Aarhus Bioacoustics lab website:
https://marinebioacoustics.wordpress.com/publications/
Kindest regards,
Chloe
Chloe Malinka, PhD Fellow
.
Zoophysiology, Dept. Biology
Aarhus University
Denmark
.
Email:
chloe.e.malinka@bios.au.dk
Twitter: @c_malinka
