Killer whale boys depend on mummy

Published on 14/09/2012 01:16

They have a fearsome reputation, but in reality killer whales are mummy’s boys.

Scientists have discovered that mother killer whales have the longest menopause of any non-human species – so they can care for their adult sons.

Female killer whales stop reproducing in their 30s or 40s, but can live beyond the age of 90. The reason for the creature’s long menopause is a long-standing mystery.

Only a handful of other species halt female reproduction part-way through their lives.

The team of British and Canadian scientists analysed 36 years of records from two killer whale populations in the North Pacific.

They found that the length of time a female lived after she stopped reproducing influenced the survival of her offspring.

For an adult male over the age of 30, the death of his mother increased the likelihood of him also dying within a year 14-fold.

Dr Dan Franks, from the Department of Biology at the University of York, said: “Our analysis shows that male killer whales struggle to survive without their mother’s help. The need for mothers to care for their sons into adulthood explains why killer whales have evolved the longest post-reproductive lifespan of any non-human 
animal.”