[MARMAM] New Publication: Sound variation and function in captive Commerson's dolphins (Yayoi M.Yoshida)

yayoi yoshida yyoshida at wrc.kyoto-u.ac.jp
Tue Oct 7 19:32:46 PDT 2014

The following was just published online:

Yayoi M. Yoshida,Tadamichi Morisaka, Mai Sakaib, Mari Iwasaki, Ikuo Wakabayashi,
Atsushi Seko, Masahiko Kasamatsu, Tomonari Akamatsu, Shiro Kohshimaa

Sound variation and function in captive Commerson's dolphins
(Cephalorhynchus commersonii)
Behavioural Processes.Volume 108, October 2014, Pages 11–19


Commerson's dolphin (Cephalorhynchus commersonii), one of the smallest
dolphin species, has been reported to produce only narrow-band
high-frequency (NBHF) clicks and no whistles. To clarify their sound
repertoire and examine the function of each type, we analysed the
sounds and behaviour of captive Commerson's dolphins in Toba Aquarium,
Japan. All recorded sounds were NBHF clicks with peak frequency >110
kHz. The recorded click-trains were categorised into four types based
on the changing pattern of their Inter-click intervals (ICI):
Decreasing type, with continuously decreasing ICI during the last part
of the train; Increasing type, with continuously increasing ICI during
the last part; Fluctuating type, with fluctuating ICI; and Burst-pulse
type, with very short and constant ICI. The frequency of the
Decreasing type increased when approaching an object newly introduced
to the tank, suggesting that the sound is used for echolocation on
approach. The Burst-pulse type suddenly increased in front of the
object and was often oriented towards it, suggesting that it was used
for echolocation in close proximity to the object. In contrast, the
Increasing type was rarely recorded during approach, but increased
when a dolphin approached another dolphin. The Increasing and
Burst-pulse types also increased when dolphins began social
behaviours. These results suggest that some NBHF clicks have functions
other than echolocation, such as communication.

Everyone can download this paper from the following site:

Or please email me at "yyoshida at wrc.kyoto-u.ac.jp" if you have any trouble
to download it.

Sincerely best-
Wildlife Research Center, Kyoto University, Japan
Yayoi Yoshida
Mail:marsh.greensdolphin at gmail.com, yyoshida at wrc.kyoto-u.ac.jp

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