Whale migration pattern written into their songs
The convergence of humpback whales at the Kermadec Islands is the human equivalent of a singing competition at a favourite gathering place, where new songs are shared and old ones reveal a lot about where you are from, new research suggests.
Like many animals including humans, humpback whales ‘culturally transmit’ behaviour including vocal traditions and vocal learning. Male humpbacks perform complex song displays that change over time but how this happens has always been something of a mystery.
Now a new study by Associate Professor Rochelle Constantine from the University of Auckland, Dr Ellen Garland, a New Zealand scientist based at the University of St Andrews in the UK, and an international team of researchers analysed recordings of humpback whales to show songs are shared between different whale populations and the Kermadec gathering may play a key role.
Humpback whales migrate each year from their winter breeding grounds in the South Pacific to Antarctica where they feed on krill over summer. En route from north to south, Department of Conservation rangers recently discovered they converge near Raoul Island in the Rangitahua - Kermadec group.
During a Southern Ocean Research Partnership voyage to the Kermadecs, Associate Professor Constantine and a team of researchers had focused on discovering the whales’ breeding ground origins by deploying satellite tags to track their migration to the Southern Ocean.
But what they also discovered was that the whales at the Kermadecs were singing – a lot more than expected.
“We didn’t expect to hear that much whale song, but our recordings on that trip could then be compared to 52 whale songs Dr Garland and other researchers from the South Pacific Whale Research Consortium had recorded in New Caledonia, French Polynesia, the Cook Islands, Tonga and Niue.
“That song comparison showed the whales at the Kermadecs had come from a wide range of breeding grounds and that was a surprise. It suggests the Kermadecs is an important place where the whales hear songs of other whales and those songs are being transmitted and learned among them.
“Until now, we never knew where whales from the different South Pacific breeding grounds met and shared this information; the Kermadecs are a very special place for humpback whales.”
As the humpback population recovers from decades of whaling, we are looking forward to more being seen in New Zealand’s northern-most waters, a place where they can continue to share song before their long journey to the Southern Ocean, Associate Professor Constantine says.
The study is published in The Royal Society Open Science Journal