A study of killer whales in the North Pacific reveals that mothers make a “lifetime sacrifice” for their sons, BTA reports.
Its authors from the University of Exeter, UK, have found that breeding a male specimen significantly reduces the chances of female killer whales reproducing in the future.
The energy they need to feed their sons appears to be putting their health at risk. As a result, their ability to reproduce and raise other young is reduced.
“Mothers are sacrificing their own food and energy,” says Professor Darren Croft of the research team.
Killer whales remain closely associated with families throughout their lives. And while young females become independent in adulthood, males remain attached to their mothers and even demand a share of the food they catch.
Professor Croft described the research as “a new insight into the complex social and family lives of these amazing animals”.
The decades-long study, published in the journal Current Biology, is part of an ongoing mission to understand the family life of killer whales.
This is possible thanks to the Center for Whale Research (CWR), which has been tracking the lives of a population of killer whales for more than 40 years. This enables biologists to study multiple generations, “unpicking” important social behaviors and family bonds that directly affect animal survival.
For the purpose of the present study, the specialists studied the lives of 40 female killer whales between 1982 and 2021. The researchers found that for each living son, the mother’s probability of raising another cub by the age of one was halved.
Previous research has shown that sons have a better chance of survival if their mother is nearby.
“We wanted to find out if this assistance comes at a cost, and the answer is yes. Orca mothers pay a high price in terms of their future reproduction to keep their sons alive,” said Dr Michael Weiss from the University of Exeter and the Center for whale research.
The researchers believe that this is probably a kind of evolutionary “bet” due to the fact that the largest and oldest males become fathers of numerous offspring.
“If the mother succeeds in turning her son into the largest male in the population, then he is the one who will father a large part of the next generation,” explains the expert.
It may seem paradoxical that such strong and intelligent animals remain dependent on their mothers throughout their lives, but males simply do not need to seek independence because their mothers stay by their side.
“If my mum made dinner for me every night, I might just never learn to make it myself,” jokes Professor Croft.
Currently, the population numbers only 73 killer whales. For this reason, scientists want to understand everything that can be useful in making decisions about the conservation of these marine mammals.
