[MARMAM] Recent papers on odontocete acoustics

Frants Jensen frants.jensen at gmail.com
Mon Jan 16 21:03:10 PST 2012

Dear colleagues,

I am pleased to announce the publication of the following paper in the
Journal of the acoustical society of America:

*Jensen, F. H., Beedholm, K., Wahlberg, M., Bejder, L., and Madsen, P. T.
(2012). *
"Estimated communication range and energetic cost of bottlenose dolphin
whistles in a tropical habitat," J Acoust Soc Am 131, 582-592.

URL: http://link.aip.org/link/?JAS/131/582
DOI: 10.1121/1.3662067

*Abstract: *
Bottlenose dolphins (*Tursiops* sp.) depend on frequency-modulated whistles
for many aspects of their social behavior, including group cohesion and
recognition of familiar individuals. Vocalization amplitude and frequency
influences communication range and may be shaped by many ecological and
physiological factors including energetic costs. Here, a calibrated
GPS-synchronized hydrophone array was used to record the whistles of
bottlenose dolphins in a tropical shallow-water environment with high
ambient noise levels. Acoustic localization techniques were used to
estimate the source levels and energy content of individual whistles.
Bottlenose dolphins produced whistles with mean source levels of 146.7±6.2
dB re. 1 μPa(RMS). These were lower than source levels estimated for a
population inhabiting the quieter Moray Firth, indicating that dolphins do
not necessarily compensate for the high noise levels found in noisy
tropical habitats by increasing their source level. Combined with measured
transmission loss and noise levels, these source levels provided estimated
median communication ranges of 750 m and maximum communication ranges up to
5740 m. Whistles contained less than 17 mJ of acoustic energy, showing that
the energetic cost of whistling is small compared to the high metabolic
rate of these aquatic mammals, and unlikely to limit the vocal activity of
toothed whales.

Also, the following publication investigating sound production at depth for
deep-diving pilot whales recently appeared in print in proceedings of the
royal society of London B:

*Jensen, F. H., Marrero Perez, J., Johnson, M., Aguilar Soto, N., and
Madsen, P. T. (2011). *
"Calling under pressure: short-finned pilot whales make social calls during
deep foraging dives," Proc R Soc Lond B 278, 3017-3025


Toothed whales rely on sound to echolocate prey and communicate with
conspecifics, but little is known about how extreme pressure affects
pneumatic sound production in deep-diving species with a limited air
supply. The short-finned pilot whale (*Globicephala macrorhynchus*) is a
highly social species among the deep-diving toothed whales, in which
individuals socialize at the surface but leave their social group in
pursuit of prey at depths of up to 1000 m. To investigate if these animals
communicate acoustically at depth and test whether hydrostatic pressure
affects communication signals, acoustic DTAGs logging sound, depth and
orientation were attached to 12 pilot whales. Tagged whales produced tonal
calls during deep foraging dives at depths of up to 800 m. Mean call output
and duration decreased with depth despite the increased distance to
conspecifics at the surface. This shows that the energy content of calls is
lower at depths where lungs are collapsed and where the air volume
available for sound generation is limited by ambient pressure. Frequency
content was unaffected, providing a possible cue for group or species
identification of diving whales. Social calls may be important to maintain
social ties for foraging animals, but may be impacted adversely by vessel

I hope you may find the papers interesting. Please feel free to contact me
for PDF versions.

Best regards,
Frants H. Jensen

Frants Havmand Jensen,
Danish Council for Independent Research, Natural Sciences Postdoctoral
Woods Hole Oceanographic Institution, MA, USA
Phone: (+1) 508 524 8436
Email: Frants.Jensen at gmail.com
Web: www.marinebioacoustics.com
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