Sometimes when you travel, you still betray where you came from when you open your mouth. The same thing seems to apply to humpback whales: features of their songs can reveal where they originally came from. What’s more, when whales travel their songs change as they pick up new tunes from whales they meet that have come from different regions.
“Our best analogy is hit human fashion and pop songs,” says Ellen Garland at the University of St Andrews in the UK. The sharing of whale song is a kind of cultural transmission that can give clues about where a whale has travelled on its migration, and where it started out. “We can pinpoint a population a whale has likely come from by what they are singing,” she says.
Garland and her team recorded the songs of humpback whales passing near the Kermadec islands in the South Pacific during September and October of 2015. They also recorded whale songs at spots where whales congregate to feed and breed across the western and central South Pacific, and around eastern and western Australia.
The team broke down each song into units, like notes, that build together to make a phrase, and several phrases that repeat to form a theme. A few themes are sung in a set order to form a song. They found three song types from 52 whales. Song type 1 was dominant in the central Pacific, including the Cook Islands and French Polynesia. Song type 2 was most common in the west, including New Caledonia, Tonga and Niue. And song type 3 was only recorded in the waters near eastern Australia.
Then they compared these songs to those of the whales near the Kermadec islands, a migratory stopover. Here they found two distinct versions of song type 1, which they’ve called 1a and 1b. These songs can morph as whales pass them along, adding a riff or a few notes.