Whispering southern right whale mums and calves seek refuge in surf

JULY 11, 2019

by The Company of Biologists

Most mammalian new mums are fiercely protective of their precious offspring; even 5-8 m long southern right whale calves are vulnerable to attack by voracious killer whales. Mia Nielsen from Aarhus University, Denmark, explains that whale mothers and calves often try to hide from predators by gravitating to cloudy water. But the loss of visual contact could force mothers and their young to call to each other more, increasing the risk of attracting the wrong attention. Knowing that humpback whale mothers resort to whispering to their young to protect them from harm, Nielsen and her colleagues, Lars Bejder from the University of Hawaii at Manoa and Peter Madsen, also from Aarhus University, decided to listen in on the conversations between southern right whale (Eubalaena australis) mothers and their calves, to find out how they go unnoticed. The team publishes its discovery that the mothers and their calves shelter in the noisy surf, stay in close proximity and effectively whisper—calling softly less than once per dive—to avoid attracting any unwanted attention in Journal of Experimental Biology.

'One of the initial challenges was getting to know the whales in our study area', says Nielsen, who travelled to Flinders Bay—off the southern tip of Western Australia where the whales breed—with Madsen, Bejder and Fredrik Christiansen to track the graceful creatures. 'The number of whales that frequent the bay is low', says Nielsen, who admits that she was surprised when they eventually located the females with their calves in the surf zone close to shore; which puzzled the researchers. Why were the mothers taking refuge in the most turbulent water? Were the crashing waves providing acoustic cover? And would the mothers and their offspring call to each other more frequently in the stirred-up water to keep in touch?

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