In the South Pacific, a humpback whale karaoke lounge

The island of Raoul, a volcanic-sized land mass twice as small as Manhattan, is not an obvious place for a whale festival. But in the last decade or so, Dr. Constantine said, conservation department rangers had noticed an accumulation of humpback whales in September and October.

"Instead of just swimming in a straight line to the feeding grounds, which is the fastest point from A to B, they will go out of their way to spend time on the island," said the doctor. Constantine.

In 2015, she and some of her colleagues traveled to this country to understand what they were preparing.

When the researchers immersed a hydrophone or underwater microphone in the water, they were "quite surprised at the amount of songs we heard," Dr. Constantine said. The songs – which the researchers could also hear through the hulls of their boats – were not as strong or as vigorous as they usually are on the breeding grounds. But at all times, there was almost always at least one whale that was happening.

An acoustic analysis of the songs revealed to the researchers that song whales originated from different breeding grounds, a conclusion reinforced by photo identification and subsequent genetic testing. They even recorded a hump song singing two different songs, perhaps learning one of the migrating whales.

Although the study sample is small (only a few dozen whales have been recorded), the authors "clearly showed that it was possible to transmit cultural songs," said Melina Rekdahl, a marine conservation scientist from the Wildlife Conservation Society. not involved in the research.

She added that such a transmission could also occur in other places, such as feeding grounds, and that questions remained unanswered, including why some South Pacific groups do not have access to food. were not found on the island and why the songs always seemed to move from west to east.

But one piece of the puzzle seems to have been placed. "The big mystery for us was: Where is the place where they share the song?" Said Dr. Constantine. "And we found it!"