Discoveries

February 21, 2023

Momma’s Boys

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Killer whale mothers are so bonded with their sons that it becomes dangerous to their well-being, according to a new study.

Researcher Michael Weiss and his team initially observed the parenting style of an adult female Southern Resident killer whale – dubbed K16 – for two decades. They found that the whale sacrificed a lot to take care of her son, even after her offspring reached adulthood, NPR reported.

K16 gave birth to her male calf, K35, 20 years ago and since then, mother and son have been inseparable: Weiss said that both mother and son shared food, which was actually hunted by K16 herself – as male orcas are large and less maneuverable, which makes it hard to catch prey.

The problem was that K16’s dedication prevented her from having other calves, including females. And she isn’t alone.

Weiss’ team studied four decades of records on Southern Resident killer whales in the Pacific Northwest and found that mothers put themselves on the line for their sons most of the time.

They observed that sons can end up becoming too dependent on their moms: Many of the sons die a year or two after their mothers pass away.

Still, researchers explained that the payoff of this parenting strategy was that the males would eventually become large and healthy fathers, eventually having offspring themselves.

But they warned that the small population of 73 whales actually needs more reproductive females than males, raising concerns that the reproductive strategy could raise their risk of extinction.

This story originally appeared in the February 21, 2023 newsletter, Winter of Discontent.