Orca mothers may act as mediators, keeping calves out of fights, study finds

Moms will do whatever it takes to support their babies — and in the case of orcas, even fending off bullies.

Female killer whales are known to be protective animals, spending a lot of time helping their offspring.

Researchers have previously observed them sharing fish catches with their pups, but now note that they also protect them from their fellow orcas.

“The targeting of social support is appalling,” said animal behavior scientist Darren Croft, noting that orca mothers were quick to take on the “police role”.

The research was carried out by a team from the University of Exeter who studied a pod of orcas off the Pacific Northwest coast of North America.

They live in matrilineal social units consisting of the mother, her offspring, and her daughter’s offspring.

Male orcas will breed with whales in other pods, but both they and females will remain in their natal units for life, with their mothers.

Mediation mom

Given that orcas have no natural predators, most of the protection moms provide will be for other orcas.

The research team used the Whale Research Center’s photographic census to look for signs of injury on each individual whale to determine the importance of these whale mothers.

They found that males whose mothers were still alive and not breeding had fewer tooth marks than their motherless peers or those whose mothers were still breeding.

An adult male orca with tooth rake marks.Image: David Eleferett, Center for Whale Research
An adult male orca with tooth rake marks.Image: David Eleferett, Center for Whale Research

Given that postmenopausal women had the lowest incidence of tooth marks, the researchers don’t think they’d be inclined to physically intervene in any fights.

Instead, moms can act as mediators to resolve potential fights, a theory that another study will explore.

Charli Grimes, lead author of the study, said: “Social knowledge may become more advanced with age.

“Given these close mother-child relationships, she may also be in a situation of conflict and therefore be able to signal to her sons to avoid risky behavior that they may engage in.”

The findings were published in the journal Current Biology.

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