Whales talk to each other by slapping out messages on water

Let’s try to eavesdrop

Michael Weber/Imagebroker/FLPA RM

By Alice Klein

It’s something all whale-watchers yearn to see. The sight of whales breaking the surface and slapping their fins on the water is a true spectacle – but the animals don’t do it just for show.

Instead, it appears that all that splashing is about messaging other whales, and the big splashes are for long-distance calls.

Ailbhe Kavanagh at the University of Queensland in Gatton, Australia, and her colleagues studied 94 different groups of humpback whales migrating south along the Queensland coast in 2010 and 2011.

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Humpback whales regularly leap out of the water and twist on to their backs – an action known as breaching – and slap their tails and fins in a repetitive fashion. The resulting sounds travel underwater and could possibly communicate messages to other whales.

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The team found evidence for this idea. The animals were significantly more likely to breach when the nearest other whale group was more than 4 kilometres away, suggesting that the body-slapping sound of breaching was used to signal to distant groups.

In contrast, repetitive tail and pectoral-fin slapping appeared to be for close-range communication. There was a sudden increase in this behaviour just before new whales joined or the group split up.

It is vital for migrating whales to conserve energy because they do not eat during this time. The fact that these slapping actions were so regular and vigorous was evidence of their importance, Kavanagh says.

Slapping versus singing

Humpback whales can also make vocal sounds, including grunts, groans, barks, grumbles, snorts, “thwops” and “wops”. Male humpback whales sing, too, most likely to serenade females.

The study found that breaching and pectoral-fin slapping increased when the wind picked up, possibly because vocal sounds became less audible. “Although surface-active behaviours only give very simple information like location, it’s possible that a succession of these surface sounds could convey a little more information,” says Joshua Smith at Murdoch University in Perth, Western Australia.

Male and female humpback whales of all ages exhibit breaching and slapping behaviour during migration, breeding and feeding – suggesting they play a key role in communication, Smith says.

“Another theory is that breaching is used to dislodge parasites from the whales’ skin, but pretty much everyone agrees now that surface-active behaviours have some kind of communication function,” he says.

Journal reference: Marine Mammal Science, DOI: 10.1111/mms.12374