The study focused on tooth rake marks found on the animals' bodies, which were inflicted during confrontations with other orcas.
The research unveiled that when an adult male's post-menopausal mother is present, he is significantly less likely to be harmed.
However, despite the protective benefits experienced by four or five-tonne males, female offspring do not receive the same level of maternal attention and protection.
Lead researcher Charli Grimes, from the University of Exeter, conveyed to BBC News that the protection offered by these older mothers was highly focused and intentional: "In some way, the mother is undoubtedly trying to safeguard her sons."
Published in the journal Current Biology, the research was conducted using photographs of orcas belonging to a population residing off the Pacific coast of North America.
Ms. Grimes and her colleagues discovered a significant reduction in "socially inflicted injuries" on male offspring when they were in the company of their post-reproductive mothers.
As part of the ongoing research on these "southern resident" killer whales, the study delves into one of the key questions that biologists have been pondering:
why do the females of this species cease reproducing midway through their long lives?
Ceasing reproduction, also known as menopause in human biology, is a rarity in the animal kingdom, confined only to humans and a few whale species.
Female killer whales in the wild can live up to 90 years, with the majority surviving over 20 years beyond menopause.