[MARMAM] New publication: Hector’s dolphins (Cephalorhynchus hectori) produce both narrowband high-frequency and broadband acoustic signals

Morgan J. Martin mjmartin at sandiego.edu
Tue Feb 27 10:49:19 PST 2024

Dear Colleagues,

On behalf of my co-authors, I am very excited to share our new publication
in JASA:

*Nicoline Abildtrup Nielsen, Stephen M. Dawson, Sara Torres Ortiz, Magnus
Wahlberg, and Morgan J. Martin (2024). Hector’s dolphins (Cephalorhynchus
hectori) produce both narrowband high-frequency and broadband acoustic
signals. The Journal of the Acoustical Society of America, 155(2),
1437–1450. https://doi.org/10.1121/10.0024820

The paper is available here:

Abstract: Odontocetes produce clicks for echolocation and communication.
Most odontocetes are thought to produce either broadband (BB) or narrowband
high-frequency (NBHF) clicks. Here, we show that the click repertoire of
Hector's dolphin (*Cephalorhynchus hectori*) comprises highly stereotypical
NBHF clicks and far more variable broadband clicks, with some that are
intermediate between these two categories. Both NBHF and broadband clicks
were made in trains, buzzes, and burst-pulses. Most clicks within click
trains were typical NBHF clicks, which had a median centroid frequency of
130.3 kHz (median –10 dB bandwidth = 29.8 kHz). Some, however, while having
only marginally lower centroid frequency (median = 123.8 kHz), had
significant energy below 100 kHz and approximately double the bandwidth
(median –10 dB bandwidth = 69.8 kHz); we refer to these as broadband.
Broadband clicks in buzzes and burst-pulses had lower median centroid
frequencies (120.7 and 121.8 kHz, respectively) compared to NBHF buzzes and
burst-pulses (129.5 and 130.3 kHz, respectively). Source levels of NBHF
clicks, estimated by using a drone to measure ranges from a single
hydrophone and by computing time-of-arrival differences at a vertical
hydrophone array, ranged from 116 to 171 dB re 1 μPa at 1 m, whereas source
levels of broadband clicks, obtained from array data only, ranged from 138
to 184 dB re 1 μPa at 1 m. Our findings challenge the grouping of toothed
whales as either NBHF or broadband species.

Please feel free to email me for a PDF copy at mjmartin at sandiego.edu or
morgan.martin at boem.gov

Morgan J. Martin, PhD
*Center for Marine Acoustics*
*Bureau of Ocean Energy Management (USA)*
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