Heaviside's dolphins (Cephalorhynchus heavisidii) relax acoustic crypsis to increase communication range
Date
2018-06Author
Martin, Morgan J.
Concept link
Gridley, Tess
Concept link
Elwen, Simon H.
Concept link
Jensen, Frants H.
Concept link
Metadata
Show full item recordCitable URI
https://hdl.handle.net/1912/10505As published
https://doi.org/10.1098/rspb.2018.1178Keyword
Acoustic crypsis; Active space; Communication; Echolocation; Heaviside’s dolphin; Narrowband high-frequency clicksAbstract
The costs of predation may exert significant pressure on the mode of communication used by an
animal, and many species balance the benefits of communication (e.g. mate attraction) against
the potential risk of predation. Four groups of toothed whales have independently evolved
narrowband high-frequency (NBHF) echolocation signals. These signals help NBHF species
avoid predation through acoustic crypsis by echolocating and communicating at frequencies
inaudible to predators such as mammal-eating killer whales. Heaviside’s dolphins
(Cephalorhynchus heavisidii) are thought to exclusively produce NBHF echolocation clicks with
a centroid frequency around 125 kHz and little to no energy below 100 kHz. To test this, we
recorded wild Heaviside’s dolphins in a sheltered bay in Namibia. We demonstrate that
Heaviside’s dolphins produce a second type of click with lower frequency and broader
bandwidth in a frequency range that is audible to killer whales. These clicks are used in burst-pulses and occasional click series but not foraging buzzes. We evaluate three different
hypotheses and conclude that the most likely benefit of these clicks is to decrease transmission
directivity and increase conspecific communication range. The expected increase in active space
depends on background noise but ranges from 2.5 (Wenz Sea State 6) to 5 times (Wenz Sea State
1) the active space of NBHF signals. This dual click strategy therefore allows these social
dolphins to maintain acoustic crypsis during navigation and foraging, and to selectively relax
their crypsis to facilitate communication with conspecifics.
Description
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society B. Biological Sciences 285 (2018): 20181178, doi:10.1098/rspb.2018.1178.
Collections
Suggested Citation
Preprint: Martin, Morgan J., Gridley, Tess, Elwen, Simon H., Jensen, Frants H., "Heaviside's dolphins (Cephalorhynchus heavisidii) relax acoustic crypsis to increase communication range", 2018-06, https://doi.org/10.1098/rspb.2018.1178, https://hdl.handle.net/1912/10505Related items
Showing items related by title, author, creator and subject.
-
Estimated communication range and energetic cost of bottlenose dolphin whistles in a tropical habitat
Jensen, Frants H.; Beedholm, Kristian; Wahlberg, Magnus; Bejder, Lars; Madsen, Peter T. (Acoustical Society of America, 2012-01)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 ... -
Whistling is metabolically cheap for communicating bottlenose dolphins (Tursiops truncatus)
Pedersen, Michael B.; Fahlman, Andreas; Borque-Espinosa, Alicia; Madsen, Peter T.; Jensen, Frants H. (Company of Biologists, 2019-12-03)Toothed whales depend on sound for communication and foraging, making them potentially vulnerable to acoustic masking from increasing anthropogenic noise. Masking effects may be ameliorated by higher amplitudes or rates ... -
Sonar-induced pressure fields in a post-mortem common dolphin
Foote, Kenneth G.; Hastings, Mardi C.; Ketten, Darlene R.; Lin, Ying-Tsong; Reidenberg, Joy S.; Rye, Kent (Acoustical Society of America, 2012-02)Potential physical effects of sonar transmissions on marine mammals were investigated by measuring pressure fields induced in a 119-kg, 211-cm-long, young adult male common dolphin (Delphinus delphis) cadaver. The specimen ...