Humpback whales "practice" their songs before seeking out a mate.

Male humpback whales, or Megaptera novaeangliae, are arguably among the most famous vocalists in the animal kingdom. They perform melodious songs that can be heard over long distances. According to several experts, these songs may serve to attract females for mating or to ward off rivals.

During the breeding season, whales sing for several days, both individually and in "choirs." The songs of these creatures consist of complex sequences of sounds that form stereotypical "phrases." These "phrases" are repeated numerous times, resulting in the formation of "themes." A song may include four to seven different themes, which are then performed in a specific order.

A team of cetologists from Canada, led by Erin Wall from the Raincoast Conservation Foundation, discovered that whales actually begin singing several months before migrating to warm tropical waters, where they will mate. These performances are likely a form of "rehearsal": this way, whales practice the song they will ultimately perform in breeding areas.

Wall and her colleagues used a network of 17 hydrophones (devices for receiving sound and ultrasound underwater) along the Pacific coast of Canada to record and analyze the songs of males in feeding grounds during the summer and fall. In winter and spring, male humpback whales migrate to Hawaii and Mexico, where their breeding season begins.

During fieldwork, researchers noticed that humpback whales sang very rarely in the summer — presumably because they were busy foraging for food. However, in September, the situation changes. Males start performing songs lasting three to four minutes, primarily consisting of short playful "phrases," but then the songs become longer. By December, they extend to 10-20 minutes. According to Wall, the animals begin to rehearse the song with which they plan to "impress" a female.

Since all males in the population sing essentially the same song, with minor individual variations, scientists suggested that this type of performance before the breeding season can be considered a joint "rehearsal" — a kind of vocal exercise.

In addition to the lengthening of songs before the breeding season, Wall also noted a change in the structure of the songs.

“At the start of the season, I would say there is much more entropy in the whale songs. A lot more variability. Then, closer to autumn, very clear themes emerge, where the stereotypical phrases begin to repeat more and more often,” explained the researcher.

It is worth noting that marine biologists and zoologists studying humpback whales do not have a consensus on whether these animals actually sing to attract females. For instance, zoologist Jim Darling from Whale Trust Maui in Hawaii mentioned that during his research on humpback whales in the northern Pacific — having studied hundreds of males — he only witnessed a male's song attracting a female once.

In any case, Wall's team's hypothesis is intriguing and deserves special attention from the international community. Confirming it will require further research conducted by several independent groups of cetologists.

Wall presented the preliminary results of her team's study at the Marine Mammalogy conference in Perth, Australia. She hopes to publish them soon in a scientific journal.