Postmenopausal orcas seem to prevent sons from getting into fights
Male orcas with a surviving postmenopausal mother have fewer signs of injury than those whose mothers are dead or still reproducing
By Chen Ly
20 July 2023
A postmenopausal female orca with its adult son
Center for Whale Research
Female orcas that have gone through menopause continue to support their sons by protecting them from conflicts with other orcas, suggests a study looking at decades of monitoring data.
Orcas (Orcinus orca), or killer whales, are one of a handful of species that go through menopause, but not much is known about why females stop reproducing in later life. Previous research has found that orca mothers provide food for their sons long after they reach adulthood, despite it restricting the mothers from having more offspring.
“[Postmenopausal] females also increase the survival of the offspring, particularly their males. They lead them to group foraging grounds and share food with them,” says Charli Grimes at the University of Exeter, UK.
Grimes and her colleagues decided to investigate whether older mothers may also protect their offspring from injuries. The team analysed photographs of 130 southern resident killer whales, a population in the north Pacific Ocean that has been surveyed annually for nearly 50 years.
They found that male orcas with a surviving postmenopausal mother had much fewer tooth marks on their skin than males whose mother was still reproducing or dead. As orcas are apex predators, these tooth marks are probably the result of conflict with other orcas. The findings suggest that the presence of a male orca’s postmenopausal mother may play a key role in resolving these clashes.
More:
https://web.archive.org/web/20230720200255/https://www.newscientist.com/article/2383509-postmenopausal-orcas-seem-to-prevent-sons-from-getting-into-fights/