Baby humpback whales "whisper" to their mothers to avoid attracting unwanted attention from predators and marauding males, scientists studying whale behaviour in Western Australia have discovered.

The quiet communication reduces the chances of being overheard by killer whales and sexually rampant male humpbacks looking for an opportunity to mate.

Whispering giants: A humpback mother and calf. Credit: Getty Images

Humpback whales are known for their loud, haunting songs, but a study using microphone tags showed that, while swimming with their mothers, newborn whales uttered intimate grunts and squeaks that could only be heard at close range.

Simone Videsen, from the University of Aarhus in Denmark, who led the research in Exmouth Gulf, Western Australia, said: "We ... heard a lot of rubbing sounds, like two balloons being rubbed together, which we think was the calf nudging its mother when it wants to nurse.