14 DAY TRIAL // Blue whales are renowned around the world for the beautiful songs they use to communicate with each other. This has become something of a trademark for the large sea mammals, which are currently endangered from excessive hunting. But, over the years, as the technology to trace and listen to them has become available, scientists have noticed something peculiar in their song patterns. They appeared to be shifting. The trend continued unabated, and now the whales exhibit completely different songs than they did just a few decades ago, Wired reports.
The thing is that scientists cannot explain this significant change. There are, of course, several ideas on why this is happening, but none of them manages to explain the phenomenon thoroughly. Each year, the mammals begin to sing in a lower voice than they did the previous year, and the trend has been consistent for some time now. Possible explanations for this include increasing the levels of noise pollution in the oceans, caused by sonars and other human activities, shifts in mating strategies, or changing population dynamics. But marine biologists say that neither of these ideas quite manages to tell the entire story.
“We don’t have the answer. We just have a lot of recordings,” Whale Acoustics President Mark McDonald explains. The company specializes in analyzing the cetaceans with sonic monitoring networks and ships. Their recordings are invaluable to experts hoping to unravel this mystery. “It’s a fascinating finding. It’s even more remarkable, given that the songs themselves differ in different oceans. There seem to be these distinct populations, yet they’re all showing this common shift,” Cascadia Research Collective blue-whale expert John Calombokidis adds. Details of the investigation appear in the October issue of the journal Endangered Species Research.
In the paper, the experts show that, each year, the pitch of the whales' tunes drops by a few fractions of a hertz. This did not alert anyone at first, as usual variations were considered responsible for the changes. But the trend kept on going for eight consecutive years, so variations were excluded. “The exciting possibility, I think, is that they’re all listening to each other. This is a worldwide cultural phenomenon, and that’s very cool,” Dalhousie University biologist and cetacean communications expert Hal Whitehead says. He underlines the fact that many individuals in different whale species learn from each other and emulate each others' behaviors. The change in pitch may be owed to that as well.