Orca moms stop having kids to take care of their adult sons, reveals study

Animals are similar to us in a lot of ways and you will be amazed to know that killer whale moms stop having more babies to take care of their male adults. Moreover, they become food deprived to feed their sons, according to a new study. The study which is published in the scientific journal, Current Biology looked at the “costly lifetime maternal investment” in three pods of killer whales that live in the Pacific Ocean. They found an interesting fact about how whale families function and how difficult it is to be a mother of an orca male, as reported by ScaryMommy. 

Michael N. Weiss of the University of Exeter, U.K., and the Center for Whale Research in the U.S., said, "We've known for over a decade that adult male killer whales relied on their mothers to keep them alive, but it had never been clear whether mothers pay a cost to do so." On the other hand, when these whales have female offspring, they leave their mother's side and apparently begin to function as a member of the pod, whether or not the daughter starts to have babies.

But that's not the case with a son, he reportedly stays by his mother's side for years and could even stay for the rest of her life, eating leftovers and behaving like a juvenile calf despite him being an adult. He does leave her side to mate but returns leaving someone else to look after his babies. “You’d think that a big killer whale male would be able to take care of himself,” Janet Mann, a behavioral ecologist at Georgetown University, told Science.

However, the unfortunate part about this story is that the mom whales often are food deprived to make sure that their sons are well-fed. "They'll even feed their sons salmon they catch," explained Prof Dareen Croft from the University of Exter, according to BBC. They also give up on expanding their family if they have a son who is eating into their resources. According to the study, a mother killer whale was 70% less likely to have another calf if they had a son "living at home." 

Eva Stredulinsky, an aquatic biologist at Fisheries and Oceans Canada also told Science, “This hasn’t really been looked at before." “It provides the first definitive description of what this support costs mothers.”

The researchers found that there are evolutionary reasons for the phenomenon among killer whales. It is because a male whale can reproduce with more killer whales and have more kids, unlike a single female. Also, like humans, killer whales also go through menopause which means that they can't have more calves after a point so they continue to take care of the adult members of their family. Weiss said, "Females gain evolutionary benefits when their sons are able to reproduce successfully, and our results indicate that these benefits are enough to outweigh a high direct cost."

Reportedly, there are only 73 of these killer whales left so the researchers want to understand anything that could help in protecting these marine animals. "These southern resident killer whales are balancing on a knife edge and at risk of extinction," said Prof Croft. "So anything that reduces females' reproduction is a concern for this population." 

Mann suggested that more research needs to be done to understand other killer whales along with marine mammals. In other animals, Weiss said, “at some point, you just stop relying on your mom as much.”