Cape Town has killer whales, and they’re top of the food chain

Killer whales, or orcas, are supreme predators that sometimes hunt dolphins in False Bay, on the east side of the Cape Peninsula and less than an hour’s drive from the city centre. Simon Elwen, principal investigator of the Namibian Dolphin Project, gives some insight into these deadly mammals.

Killer whales are often called “wolves of the sea” because they are pack hunters. They pack hunt in the same way wolves and lions do…We see the killer whales here, in False Bay, pack hunting dolphins. If you’ve got 2 000 dolphins and five killer whales hunting them, it’s kind of hard not to see.

Common dolphins form such big groups because there is safety in numbers. If you’re one of 2 000 dolphins and the killer whales are going to take out maybe two dolphins in a day, then you have a better chance of surviving.

Although the killer whales seen in False Bay are often seen chasing down common dolphins, killing and eating them, dietary studies from stranded animals suggest they eat fish as well. Like most predators, there’s always a trade-off between what’s high in energy, easy to catch, and what doesn’t bite back.

Killer whales are very smart animals. They live in very close social groups – one of the clear indicators of quite advanced brain development…The females survive beyond reproductive age because they have a role in the community as leaders. There was a really good study showing that the females’ knowledge, in terms of hunting strategy and location, is extremely valuable to the social group.

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