Killer whale moms may be feeding their sons into extinction

DW

A specific species of male orca whales live in a state of perpetual adolescence, to everyone’s potential detriment.

Manchild, mama’s boy, adult child — if you know the type, you know.

Cooking anything beyond an egg ends in disaster. And they still receive a steady allowance from their parents … at age 35. Wholly dependent on their mothers, they are stuck in a perpetual adolescence. They may have grown to rely on it or struggle to achieve independence — families can be complicated — but either way, such relationships can be bad for the whole community.

While humans are lucky this behavior is more the exception and less the rule, it’s the other way around for male orca whales, who, according to a paper published in Current Biology on February 8, remain big babies for their entire lives.

That occurs to the detriment of their mothers, who, by devoting all their time, resources and energy to their demanding sons, abstain from further reproduction.

It is a pattern that could explain the decreased reproductive output of the critically endangered species, the researchers write in the paper.

Orca moms fully invest themselves in male offspring

The study took place over nearly half a century and followed the lives of 40 female orca whales. The researchers wanted to understand why the species was becoming increasingly endangered.

They found that when female orca whales had sons their chances of giving birth to future offspring reduced by 50%. This remained the case throughout the mother’s lifetime and was not observed in orcas who gave birth to daughters.

“Killer whale mothers pay a high cost in terms of their future reproduction to keep their sons alive,” said researcher and co-author of the study, Michael Weiss, in a statement. 

Weiss is based at the Center for Research in Animal Behaviour at the University of Exeter. He and his colleagues used data from a “southern resident” orca whale population, which generally lives off the coasts of British Columbia and the U.S. states of Washington and Oregon.