Humans Aren’t the Only Mammals Who Rely on Grandmas to Babysit: Orcas Do Too

December 17, 2019 at 2:41 pm

Orca calves have a much higher chance of survival if their grandmas are around, new study finds

Killer whale grannies help raise their grand-kids until they are up to 90 years old, a new study finds.

One of the biggest services they provide is free child care, while the mothers go out hunting, to make sure they aren’t eaten by any predators. Grandmothers also take turns hunting and share their food with their grandchildren.

The presence of their grandmothers in their lives greatly increases orca calves’ survival rate.

Within two years of a grandmother’s premature death, her grand-babies’ chances of dying more than quadrupled, the study found.

Lucky for the whole family, orca grandmothers usually live to a ripe old age, sometimes up to 80 or 90 years!

Orcas are one of only five mammals (along with humans, beluga whales, narwhals and short-finned pilot whales) who go through menopause (around 45) and live long past their reproductive years.

The females of all of these species tend to stay with their offspring their entire lives.

A group of resident orcas in the inshore coastal waters of Washington state and British Columbia. Credit: Daniel W. Franks.

“The older a female gets, the more related she becomes to her local group,” lead study author Daniel Franks told Business Insider.

“This means that around the age of menopause, a female is well placed, in evolutionary terms, to pass on her genetic legacy through helping family members rather than through reproducing herself.”

Grandmother orcas act as ” repositories for ecological knowledge” and play an important leadership role for the group when foraging in salmon grounds, according to the researchers.