Though they’re separated by an entire continent, male humpback whales near Gabon and Madagascar often seem to be singing versions of the same tune.
Researchers have long known that the massive cetaceans sing complex songs, made up of single-sound units (such as moans, trumpets, or woops), multi-unit phrases, and multi-phrase themes. No one has decoded the songs entirely, but researchers suspect that male humpbacks may use higher-pitched songs to woo nearby females, and lower-pitch grumbles to stake out territory and boast to other males.
Though songs can vary from one year to the next and by individual, most males in a given pod sing a similar type. What’s surprising is that versions of the same songs can be heard thousands of miles apart, according to a team led by Melinda Rekdahl, a marine conservation scientist for the Wildlife Conservation Society’s Ocean Giants Program.
Cetacean singers really belt it out during their breeding seasons on separate side of Africa, but Rekdahl’s team suspects that an oceanic jam session of sorts happens when the whales congregate at feeding grounds to the south, around Antarctica. Though they sing less frequently down there—mating is off the menu—the mixing of songs suggests that whales are interacting with individuals who sing differently, Rekdahl and her colleagues posit in a new paper in Royal Society Open Science.
“In the animal kingdom, it’s much more common for an animal moving to a new population to pick up the song type of that population, rather than instigate radical revolution in the type of song,” Rekdahl says. But humpback whales seem to embrace new sounds, and repeat and remix what they hear as they trek back north—something like an open-ocean version of a road trip earworm you can’t get out of your head.
Have a listen to how whales on opposite sides of Africa sound, and see if you can hear the similarities and differences:
Rekdahl’s team recorded songs over several years by submerging hydrophones off of Iguela and Mayumba in Gabon, and in Madagascar’s Antongil Bay. When they analyzed the songs statistically, they found that the sounds often had a lot of overlap, which varied year by year and increased over time. Each group took some creative liberties: One pod might break a single unit into two, by replacing a descending cry-woop with a separate cry and whoop. Another might change part of a theme, replacing an onomatopoeic “yap train” with a “snort train” and a grunt. But in the last year of data collection, the songs were largely similar on both sides of Africa.
The team doesn’t yet know how many members of different groups have to mingle in order for songs to evolve, or how cozy the animals have to be. Do they learn up close, or eavesdrop from a distance? While Rekdahl and her collaborators haven’t puzzled out “the mechanism by which a male will say, ‘I’m going to ditch my old song and learn this new one,’” she says, it seems the whales are attracted to novelty—the newest and hottest on the cetacean charts. To learn more, Rekdahl says, researchers would need to get closer to the action in Antarctica, and then listen up.