[MARMAM] new publication: Weddell seals produce ultrasonic vocalizations

Lisa Munger lmunger at hawaii.edu
Sun Dec 20 10:51:14 PST 2020

*Weddell seals produce ultrasonic vocalizations*
by Paul A. Cziko*, *Lisa M. Munger, Nicholas R. Santos*, and *John M.
Published online 18 December 2020
The Journal of the Acoustical Society of America *148*, 3784 (2020);
*Abstract: *Seals (phocids) are generally not thought to produce
vocalizations having ultrasonic fundamental frequencies (≥20 kHz), although
previous studies could have been biased by sampling limitations. This study
characterizes common, yet, previously undescribed, ultrasonic Weddell
seal (*Leptonychotes
weddellii*) vocalizations. The vocalizations were identified in more than
one year (2017–2018) of broadband acoustic data obtained by a continuously
recording underwater observatory in McMurdo Sound, Antarctica. Nine
recurrent call types were identified that were composed of single or
multiple vocal elements whose fundamental frequencies spanned the
ultrasonic range to nearly 50 kHz. Eleven vocal elements had ultrasonic
center frequencies (≥20 kHz), including chirps, whistles, and trills, with
two elements at >30 kHz. Six elements had fundamental frequencies always
>21 kHz. The fundamental frequency of one repetitive U-shaped whistle
element reached 44.2 kHz and descending chirps (≥3.6 ms duration) commenced
at ≤49.8 kHz. The source amplitude of one fully ultrasonic chirp element
(29.5 kHz center frequency) was 137 dB re 1 μPa-m. Harmonics of some
vocalizations exceeded 200 kHz. Ultrasonic vocalizations occurred
throughout the year with the usage of repetitive ultrasonic chirp-based
calls appearing to dominate in winter darkness. The functional significance
of these high-frequency vocalizations is unknown.
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