Study: When Male Whales Start to Rumble, Orca Moms Step in

Aug 14, 2023

Thought Question: How can family members support and help each other when facing challenges or difficult situations? 

Has your mom ever broken up a fight you got into? It turns out killer whale mamas do it too.

A study published last month in the journal Current Biology found that when male orcas fight, their post-menopausal mothers rise to defend them. The study suggests they do so as a means of survival. The mothers are trying to make sure their genes pass on to future generations.

“Mum is definitely, in some way, trying to protect her sons,” the study’s lead author told the BBC.

Grimes and other researchers studied nearly 50 years of whale records. They looked closely at photos taken of orcas swimming off the Pacific Northwest coast. The records showed fewer “socially inflicted injuries” on males who stayed with mothers who could no longer have babies.

The researchers think post-menopausal female orcas may have more time than mothers still raising their young. That allows them to protect older male offspring from fights. And the moms don’t appear to physically involve themselves in their sons’ fights. They just make their presence known.

Grimes told the BBC she thinks the presence of the mom "can signal to her sons to avoid the risky behavior."

The study’s results fit with what scientists already know about orcas. Pods are set up as matriarchal systems. That means they are led socially by females. The group is made up of an aging female, her young, and her daughter’s calves. Males will go outside the pod to mate with females. But both female and male offspring will stay with their mother for her whole life.

Photo from Christopher Michel courtesy Flickr.

Based on the details in the story, what happened to male orcas when their post-menopausal mothers defended them during fights? (Common Core RI.5.1; RI.6.1)
a. They became more aggressive.
b. They joined other pods.
c. They experienced fewer socially inflicted injuries.
d. They were forced to leave their pod.
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