A new study from Aarhus University is describing how southern right whale mothers and calves communicate in the cloudy waters where they hide from predators. The loss of visual contact creates a need for the whales to call out to each other, but this may attract unwanted attention.
A research team led by Mia Nielsen set out to listen in on the conversations between southern right whale mothers and calves. The researchers discovered that the whales hide out in the noisy surf and whisper to each other to reduce the risk of being noticed by predators.
The study was conducted in Flinders Bay, off the southern tip of Western Australia, where the whales breed.
“One of the initial challenges was getting to know the whales in our study area,” said Nielsen. “The number of whales that frequent the bay is low.”
Nielson said she was surprised when they eventually located some females with their calves in the surf zone close to the shore. The researchers were puzzled by their decision to seek refuge in the most turbulent water.
As the whales rested at the surface, the team tagged them with sound recorders. The tags stayed on the mothers for about 7 hours, but did not even last an hour on the calves.
“Southern right whales are very physical with each other, the calves spend a lot of time rubbing against the mother and rolling over her back, tail and rostrum,” explained Nielsen. The researchers still managed to obtain nearly 63 hours of conversation between the mothers and calves as they sheltered in the surf.
An analysis of the recordings revealed that the animals were producing two types of calls: a grunt and a mooing sound. Instead of continuous communication, the mother and calf pairs called less than once per dive. The moos and grunts were found to be very quiet, and were drowned out by the noise of the pounding waves within a few hundred meters.
The study is published in the Journal of Experimental Biology.
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