Humpback Whale Top 40

Humpback whales have been in the news recently. Not only are they possibly “Migratory Astronomers,” according to new research, but they also have their own version of the hit single.

According to a study reported online last week in Current Biology, at any given time within a population, male humpbacks all sing the same mating tune. But the pattern of the song changes over time, with the new and apparently catchy versions of the song spreading repeatedly across the ocean, almost always traveling from west to east.

Ellen Garland, of the University of Queensland and lead author of the study, and her colleagues made the discovery by searching for patterns in whale songs recorded from six neighboring populations in the Pacific Ocean over a decade. (Think of her as the Casey Kasem of the whale world, reporting the hits from coast-to-coast.)

Actually, not coast to coast, but west to east across the Pacific. “The songs started in the population that migrates along the eastern coast of Australia and then moved—just the songs, and probably not the whales—all the way to French Polynesia in the east,” Garland said. “Songs were first learnt from males in the west and then subsequently learned in a stepwise fashion repeatedly across the vast region.”

The researchers suspect that either a small number of males move to other populations, taking their songs with them, or whales in nearby populations hear the new songs while they swim together on migration.

Most of the time, songs contain some material from the previous year blended with something new. “It would be like splicing an old Beatles song with U2,” Garland said. “Occasionally they completely throw the current song out the window and start singing a brand new song.”

Once a new song emerges, all the males seem to rapidly change their tune. Those songs generally rise to the “top of the chart” in the course of one breeding season and typically take over by the end of it.

Garland said it is not yet known why the humpbacks’ songs spread in this way. In fact, why whales sing in the first place isn't fully known. Song is likely a mating display, but it is unclear whether the main effect is to attract females or to repel rival males.

Still, Garland suspects that the whales may want to stand out like a new pop song. “We think this male quest for song novelty is in the hope of being that little bit different and perhaps more attractive to the opposite sex,” she said. “This is then countered by the urge to sing the same tune, by the need to conform.”

NOAA image by Dr. Louis M. Herman