The killer whale, feminine predation

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The killer whale that roamed the Seine finally died Monday. The marine mammal is a top predator, at the top of the food chain in the oceans.

His ordeal lasted for many days until its tragic end. The killer whale that roamed the Seine was finally found dead Monday when the decision was made to kill it for debilitated animals. But why did this marine mammal end up in a river, far from its natural habitat? First hypothesis made after the discovery of the animal in the Seine: sick, the killer whale would have been rejected by his family. A theory that is today disputed by several specialists contacted by RFI. “There is a huge solidarity between orcas, emphasizes Lamya Essemlali, President of the NGO Sea Shepherd France. We remember these photos taken in British Columbia [sur côte ouest du Canada] : an orc mother had carried the body of her calf for days. »

Sea Shepherd France rather points to human activities and especially noise pollution in this region of Le Havre, at the mouth of the Seine. Killer whales communicate with each other by whistling and locate each other by echoing by emitting clicks. Perceived signals up to 10 kilometers away. But beyond that, it is impossible to find his family. “There is a lot of maritime traffic, huge noise pollution, emphasizes Lamya Essemlali. It is therefore possible that the killer whale lost her group by accident and that she once had difficulty feeding herself on her own, which would explain why she was emaciated. »

Whale killers

Because orcas hunt in groups with remarkable intelligence. These two-tonne top predators, at the very top of the food chain, can, for example, strike with their tails violently on a piece of ice to knock the seal into the water. We also saw a killer whale come up out of the water with its mouth open when a penguin threw itself into the water from the top of the pack ice. Killer whales found in all oceans are also capable of attacking sharks and even whales. This is also the name of the killer whale in English: orcaskills whales.

In French, orque is a female name, because with this dolphin’s cousin, it is the females who lead the dance, who know where the prey is and how to hunt it. A matriarchal organization that is undoubtedly due to the female’s lifespan exceeding 80 years, even though orcas are no longer fertile halfway through their lives. “What is the point of surviving so long when you no longer contribute to the group’s reproduction? interrogate Christophe Guinet, CNRS research director and specialist in marine mammals. We Iexplained with this experience effect. Dominant orcas will of course raise their own young, but they will also help raise their grandchildren and great-grandchildren. This could explain this dominance role because of this experience within killer whale families. »

mother power

The females live almost twice as long as the males. “The moment the matriarch, the founding woman, dies, the daughters tend to separate and leave them with their own direct descendants, their own sons and daughters, continues Christophe Guinet. And what we also observed is that in the two years after the matriarch’s death, her sons will die because they are rejected by their sisters. » Nature is sometimes cruel.

Orcas, at the top of the food chain, have only one enemy: humans, especially fishermen, who shoot at them when they get too close to their nets. Or who, through overfishing, deplete the food resources of orcas. Even apex predators are vulnerable.

QUESTION OF THE WEEK

Are humans super-predators?

Homo sapiens is even a hyperpredator. The only animal that kills more than reason, just for fun, and the biggest prey, adults, when other predators feed on weaker prey. Apart from humans, which are responsible for the extinction of many species, apex predators contribute to the balance of nature. This is the case, for example, with the wolf that was reintroduced in Yellowstone Park in the United States. Its return helped regulate the populations of moose that devoured the vegetation. The birds have returned, as well as the scavengers, the beavers … No need to cry wolf!

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