The short version
- Pygmy blue whales off Western Australia sing less in daylight because that is when they are busy feeding.
- Researchers combined 130.1 days of tag data on diving with underwater sound recordings to show it.
- Counting night song against day song could tell scientists where an endangered population is feeding without watching it.
Pygmy blue whales in the eastern Indian Ocean have been heard singing more at night than by day. A study published on October 28 in Royal Society Open Science explains why: they are eating. Andrew Davenport, a PhD candidate at Curtin University’s Centre for Marine Science and Technology, and seven co-authors paired passive acoustic recordings with data from tags on the whales, 130.1 days of diving records in all. Statistical models showed the whales had less time to sing while feeding in daylight than while feeding at night or not feeding at all. In the Perth Canyon feeding season, night song outweighed day song for up to three months.
“Pygmy blue whales appear to have less time available to sing while they’re feeding,” Davenport said in the university’s release. The population is endangered, and the team says reading its song could help monitor and protect it.
The practical point is the ratio. If more song at night means feeding by day, then “we can infer when whales in an area are likely to be feeding,” Davenport said, from the Perth Canyon north to the northwest shelf. Neither the abstract nor the release says how many whales were tagged.
