QWho wouldn’t make a mother for the sake of her little ones? The devotion of the female elephants who do not let go of them, the courage of the female bears who protect them against the violence of the males, the abnegation of the female dolphins to teach them to swim… Not to mention the care sometimes provided throughout of their lives by mothers sbee.
However, in this little game, the mother orca holds a special place. His attachment seems limitless. We remember the images of Tahlequah who, for seventeen days, in August 2018, swam carrying the body of her dead baby on her head, depriving herself of all food. A study published Tuesday, February 8, in Current Biologyhas just shown, for the first time, that this sense of sacrifice continues into adulthood with their sons.
For more than a decade now, researchers who have been scrutinizing the fragile colony of Southern Resident killer whales along the west coast of the United States and Canada have found that adult males continually take advantage of maternal devotion. Not content with guiding them to good fishing grounds, they give them part of their own catches. “Eat, my son! » Because it is the males who benefit from the bulk of this largesse. Michael Weiss, director of research at the Center for Whale Research in the US state of Washington, who led the study, explains it by the social structure of the species – divided into several groups – and by its biology: “First, the young males reproduce outside their group, while the females keep their young close to them. So supporting the males does not impose new mouths to feed. In addition, the reproductive success of males increases with age. So it’s a worthwhile investment. »
Reduced reproductive success
An investment: this is actually the originality of this article. “Lifelong mother-child relationships are commoninsists the primatologist Elise Huchard (CNRS, Montpellier), who cites chimpanzees, bonobos but also hyenas. What is very new, however, is that these maternal influences are costly. » Michael Weiss’ team has taken advantage of individual data scrupulously collected over forty years. Every birth is reported there, as well as every death. She was thus able to demonstrate that the maintenance of a young male led a mother to lose 50% of the chance of having a baby in a given year. A second male, 50% more… “We expected to find a cost but not as high”says the researcher.
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