Orca Mothers Sacrifice to Make Sure their Sons Have a Good Life

A new study shows that these whales favor their male offspring.

(Slowmotiongli / Shutterstock.com)

Apparently, a mother’s instinct to take care of their child is a cross-species phenomenon. Research reveals that orca mothers spoil their male offspring, much like a human mother might. A new study in Current Biology shows how mothers in a herd of killer whales in the Pacific area of North America favor their male offspring to their own detriment.

About the study
Scientists studying a group of orca whales off the Pacific Coast of North America discovered something different about the family structures of the pod. According to Science News, researchers observing the group of whales noted that female whales with male offspring would share their food- mostly salmon - with their sons even after they had grown, but not with their female offspring. 

Additionally, mother orcas provide their sons with food to the detriment of their own fertility. The mother’s chance of weaning a calf drops significantly after having a son. Thus, the female whale’s choice to continue feeding their male offspring even into adulthood constitutes a significant sacrifice. 

“Mothers sacrifice their own food and their own energy," Darren Croft a behavioral ecologist at the University of Exeter told the BBC.

Genetic Advantage
According to Science News, one of the reasons orca mothers may make this sacrifice is the genetic advantage it gives them. One may think that the lower number of offspring decreases the probability of their genetic line continuing. However, male whales can inseminate a great number of female whales, with no disadvantage to themselves, while in female whales pregnancy lasts 18 months, dramatically lowering the amount of time they are available to pass on their own genetic material, especially since female orcas are one of the only species in the world besides humans to experience menopause. 

Male orcas give their mothers many more grandchildren than do female orcas, and when your survival as a species is at risk, this can make all the difference.

Croft told the BBC: "These southern resident killer whales are balancing on a knife-edge and at risk of extinction, so anything that reduces females' reproduction is a concern for this population."

Favoring one gender of child over the other is something that humanity has hopefully grown out of. However, studying orcas and their family structures may give scientists some insight into what may have pushed human ancestors to adopt strategies like these in times when they were under genetic pressure and stress.

This study is just more proof that humanity has so much to learn from the natural world, and how important it is to cherish it.

This Year’s Reprieve for Iceland’s Whales May Last Forever!
Whales Have Something to Cheer About!
Humpback Whale Population Bounces Back