Baby whales 'whisper' to mothers to avoid predators: study

April 26, 2017 by Valerie Dekimpe
A mother-calf pair in Exmouth Gulf. Credit: Fredrik Christiansen

Newborn humpback whales and their mothers whisper to each other to escape potential predators, scientists reported Wednesday, revealing the existence of a previously unknown survival technique.

"They don't want any unwanted listeners," researcher Simone Videsen, lead author of a study published in Functional Ecology, told AFP.

"Potential predators such as killer could listen to their conversations and use that as a cue to locate the calf and predate on it."

Whales are known for their loud calls, congregating fellow members of the pod. Male humpback whales also emit reverberating sounds to attract females during the mating season.

But this is the first time scientists have observed a unique, intimate form of communication between humpback mothers and calves.

Researchers from Denmark and Australia tracked each of eight calves and two mothers for 24 hours in Exmouth Gulf, Western Australia, a breeding ground for Antarctic humpback whales seeking warmer waters to mate and give birth.

Using tags attached to the animals, the team of scientists recorded their faint squeaks and grunts.

"These signals between mother and calf are more quiet than those of normal adult ," Videsen said, noting they were 40 dB lower than the singing of males in the area.

While a male's cry can resound over an area covering several kilometres, the pairs in the study could only hear each others' calls within a distance of less than 100 metres (330 feet), she added.

A mother-calf pair in Exmouth Gulf. Credit: Fredrik Christiansen

The low sounds were detected when the pairs were swimming, suggesting the discreet tone helps the mammals stay together in the murky breeding waters, infested with preying on stray calves.

Marine noise pollution

The faint sounds are also a way to keep mate-seeking males from interfering in the humpback's nurturing, a crucial time in the newborn's life as it braces for an arduous 8,000-kilometre (5,000 mile) journey back home to the Antarctic, the researchers speculated.

And the migration is no less challenging for the mother.

"There is no food for them in the breeding grounds so the mothers feast while they are there," Videsen said.

The researchers also believe that mother and calf—in their effort to go undetected— may have developed a silent method to initiate suckling.

Instead of signalling hunger vocally and risk getting spotted, the calves "rub against their ," according to the study's findings.

Humpback whales can be found both in the Arctic and Antarctic. Each pod spends the summer at the poles and travels to tropical areas in their respective hemispheres during the winter to breed.

The scientific investigation also shed light on the growing problem of ocean that can severely disrupt marine life.

"Because mother and calf communicate in whispers, shipping noise could easily mask these quiet calls," Videsen said, potentially provoking the pair to lose each other.

Explore further: Endangered right whales deliver fewest births in 17 years

More information: Simone K. A. Videsen, Lars Bejder, Mark Johnson and Peter T. Madsen 'High suckling rates and acoustic crypsis of humpback whale neonates maximise potential for mother-calf energy transfer', Functional Ecology (2017). DOI: 10.1111/1365-2435.12871

Related Stories

Endangered right whales deliver fewest births in 17 years

April 12, 2017

Endangered North American right whales gave birth last winter to the fewest calves seen off the U.S. coast in 17 years, troubling scientists who say the low births support other evidence that the imperiled species' population ...

Recommended for you

Engineering cellular function without living cells

March 25, 2019

Genes in living cells are activated – or not – by proteins called transcription factors. The mechanisms by which these proteins activate certain genes and deactivate others play a fundamental role in many biological processes. ...

What ionized the universe?

March 25, 2019

The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its ...

Catalyst advance removes pollutants at low temperatures

March 25, 2019

Researchers at Washington State University, University of New Mexico, Eindhoven University of Technology, and Pacific Northwest National Laboratory have developed a catalyst that can both withstand high temperatures and convert ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.