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Baby humpback whale recordings reveal vocalizations directed to their mothers

A team of marine biologists, zoologists, and cetologists from Université Paris-Saclay, Université d'Antananarivo and Ambodiforaha Sainte Marie has learned more about the ways baby humpback whales and their mothers communicate.

In their study in the journal Proceedings of the Royal Society B: Biological Sciences, the group attached camera-equipped, multi-sensor tags to several of the whales and then analyzed the sounds they emitted under different contexts, such as during feeding or play.

Prior research has shown that humpback whales use sounds for a wide variety of purposes, including communication with others of their kind, mating signals and sensory perception. Humpback whale vocalizations usually come as a series of repetitious sounds at varying frequencies, leading many in the field to refer to them as songs.

For this new study, the research team switched their attention from the vocalizations of adult whales communicating with one another to calves communicating with their mothers.

The research team affixed devices capable of recording both video and audio to eight calves living with their mothers off the coast of Sainte Marie Island. They then analyzed the 33 hours of recorded material back in their lab.

One of the first parts of their analysis involved separating out the sounds made by the calves from all others, including their mothers. They then studied voicings across multiple baby whales during certain behaviors such as nursing, playing and simply sitting idle. This allowed them to note patterns in the way the whales spoke to their mothers when they wanted different things, or when they were simply attempting to express themselves.

The researchers found that the young whales tended to get noisy just before nursing in the morning—and such periods of noise lasted the longest of all those they studied. They also noted that such vocalizations tended to be low-frequency and also included what they describe as snorts, barks, grunts and burps, which they suggest are likely forms of begging to be fed.

The researchers studied 500 calls in all and noted that the calves were most quiet during downtimes, such as when traveling, and grew louder during times when they were allowed to play on the water's surface.