Humpback whale populations separated by distances of as much as 14,000km have been found singing the same mating songs, by researchers at Scotland’s University of St Andrews.
Humpbacks (Megaptera novaeangliae) sing a “repetitive, socially learnt and culturally transmitted” song that slowly evolves year by year, say the scientists. Most males within any one population sing this same song type, but in the South Pacific the scientists identified that these songs are undergoing rapid, complete replacement by new ones learnt from neighbouring populations.
These “song revolutions” were known to have spread east across the Pacific from eastern Australia to cover the 6,000km to French Polynesia, but the research team set out to investigate whether they went on spreading further east towards South America.
Using three consecutive years of song data from between 2016 and 2018, they found that the French Polynesian song matched themes – multiple repeated phrases – found in humpbacks’ song in Ecuadorian breeding grounds in 2018. This suggested that connectivity existed across the entire south Pacific.
It has yet to be demonstrated whether whale songs continue migrating east across the Indian Ocean to get back to where they started in Australia. However, the researchers say that their findings support the possibility that the songs can be transmitted all the way round the southern hemisphere – albeit evolving along the way – in a “vocal culture rivalled in its extent only by our own”.
They believe it’s possible that the whales get the chance to share their songs while gaining mass before their winter breeding season, or while migrating. The study is published in Royal Society Open Science.
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