The rivalry of female killer whales

A young female is only loosely related to the other members of her pod, because they all have different fathers, writes Richard Collins.

A female killer whale can breed at 15 years of age. She will live on for decades and may even celebrate her 90th birthday, but she stops having babies at 40. Only two other species are known to go through menopause — short-finned pilot-whales and humans.

Young female mammals tend to settle close to where they were born, while their brothers seek their fortunes elsewhere. Killer-whale youths, however, do things differently; they remain tied to their mothers’ apron strings for life. A killer-whale pod will have a matriarch, her daughters, grand-daughters, sons and grandsons. None of the males present will be members’ daddies because males don’t mate with the females of their own pod, but leave for brief encounters elsewhere. Meanwhile, their sisters entertain visiting Casanovas.