Scientists ‘Fascinated and Horrified’ as Killer Whale Drowns Another Orca’s Calf

An orca calf swims alongside its mother shortly before it is attacked by a male killer whale, in the first documented case of killer whale infanticide. (Jared Towers)

When Jared Towers and two of his colleagues set out to observe a group of orcas off the coast of Vancouver Island, they assumed it would be a routine excursion. In fact, Towers, a cetacean researcher with Fisheries and Oceans Canada, was already familiar with this particular pod of killer whales, having documented them on previous research trips.

For an hour, the trio of humans photographed and identified several of the whales — including an orca calf that appeared to be no older than a day, or even a few hours, judging by the fetal folds still visible on its body and a dorsal fin that wasn’t fully standing up.

The December 2016 boat trip “wasn’t anything too out of the ordinary,” Towers told The Washington Post. “After about an hour, we were just about to go back to the office and call it a day.”

That was when the group of scientists witnessed something they say they’ll never forget.

Ahead of them, some splashing, noise and “erratic movements” caught their attention. Towers said they figured the group was attacking some prey.

“We got a little closer and realized that the baby whale we observed earlier wasn’t surfacing,” Towers said.

Moments later, a male orca swam by with something in its teeth.

“The baby was hanging out of his mouth,” Towers said. “I knew right off the bat — I study killer whales pretty intensively — that this was a ‘first of its kind’ kind of observation.”

Immediately, the researchers dropped a hydrophone into the water and into “data collection mode” for the next five hours. They watched with a mix of agony and awe as the male orca proceeded to drown the calf, all while its mother tried in vain to stop the killing of her baby, he said.

“We were a bit horrified, but more so I think we were fascinated,” Towers said. “We knew that it was time to just collect as much data as we could to accurately record our observations.”

Though the expedition took place more than a year and a half ago, the observations by Towers, Muriel Halle and Gary Sutton were published just this week in the journal Scientific Reports. It is the first recorded instance of an orca killing a calf of the same species, providing evidence that killer whales engage in infanticide, a behavior reported in many species.

Among land mammals, infanticide occurs among primates and rodents, the report noted. It also occurs in some dolphin species. It is often “a behavior that leads to sexual behavior,” Towers said.

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SOURCE: The Washington Post, Amy B Wang