[MARMAM] New publication on a diel patterns in singing activity of humpback whale in Okinawan waters

小林 希実 n-kobayashi at okichura.jp
Mon Mar 1 20:12:53 PST 2021

Dear MARMAM community,
My co-authors and I are pleased to announce you on our new publication titled, Diel patterns in singing activity of humpback whales in a winter breeding area in Okinawa (Ryukyuan) waters, which is now available in the journal of Marine Mammal Science.
by Nozomi Kobayashi, Haruna Okabe, Naoto Higashi, Hirokazu Miyahara, Senzo Uchida
Male humpback whales produce complex sounds known as songs during their breeding season. 
Previous studies have shown diel patterns of song in their breeding areas, but there had been no similar studies in the breeding area around Okinawa, Japan. 
To study diel patterns of song and the behavior of humpback whales in Okinawa, we conducted 24 hr recording with a fixed hydrophone in 2007, and vessel‐based sighting surveys during 2014–2017. 
Song was monitored for 15days, with peaks at sunrise and around 2200. 
Singing activity declined significantly between sunrise and sunset, then increased until 2200. 
Activity levels at night were higher and more stable than during the day. 
During 278 days of sighting surveys, 2,551 whales in 1,382 groups were observed. 79 individuals were confirmed as singers, all of which were lone whales. 
In six cases, singing individuals stopped singing before joining a group or began singing after leaving a group. 
Previous studies have shown that group size of humpback whales increases through the day. 
Considering the results from our study and the former studies, the decrease in singing activity as the day progresses may be a result of aggregation increasing, thus reducing the number of lone singers during the day.
This article can be obtained from 
Please feel free to contact us if you have any questions!
Kind Regards,
Nozomi Kobayashi

Nozomi Kobayashi, Ph. D.

Zoological Lab.
Okinawa Churashima Research Center 
Okinawa Churashima Foundation

E-mail:n-kobayashi at okichura.jp

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