Recordings of male humpback whales have shown that their unique songs spread far through the ocean to other whales.
Over more than a decade, researchers in Australia have been listening to and recording hundreds of hours of these songs. They have revealed how a specific song pattern, which originated in Eastern Australia, has reached whale populations up to 6,000 km away in French Polynesia. The research, led by Ellen Garland from the University of Queensland, is published in the journal Current Biology.
The research team say the findings show the animals transmit these “cultural trends” over huge distances.
“Within a population, all males sing the same song,” Garland explained. “But that song is constantly changing. So we wanted to look at the dynamics of songs throughout an ocean basin.”
Garland and her research team studied recordings of 775 humpback whale songs, recorded by scientists from the South Pacific Whale Research Consortium.
“Lots of different sounds make up each song,” said Garland. “There are low frequency moans, groans and growls then higher cries and shrieks and all variations of ascents and descents.”
Patterns of these sounds make up phrases that the whales repeat for up to 30 minutes.
Using software to analyze the songs, Garland and her colleagues found that four new songs that emerged in a population in Eastern Australia gradually spread eastward. Within two years, whales in French Polynesia were singing the same verse.
“It’s a culturally-driven change across a vast scale,” said Ms Garland. The research team believes that the whales in the South Pacific may hear and learn songs during their annual migration to their feeding grounds in Antarctica.
“The East Australian population is the largest in the region with over 10,000 humpbacks,” Ms Garland explained. The large population means that these whales have more influence on what songs are passed on.
Peter Tyack, a biologist from Woods Hole Oceanographic Institution in Massachusetts, US, said the results showed “a new way to look at culture in these animals”.
“These are very mobile animals; they can swim hundreds of kilometers in a day… and their song carried very well underwater,” he said. There is still debate over whether male humpbacks’ songs are directed at females or at other males, but most scientists agree that song plays a role in reproduction.
“We have good behavioral observations of singers competing with each other and of females moving to join the singers, so we think it’s associated with mating,” explains Dr. Tyack.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC