Mysteries of Killer Whales Uncovered in the Antarctic

On the afternoon of January 10, at the tip of the Antarctic Peninsula, whale researchers Robert L. Pitman and John W. Durban stood on the bridge of a cruise ship, peering through binoculars for signs of killer whales. The Weddell Sea, where English explorer Ernest Shackleton and his men were locked in the sea ice nearly a century ago, was calm and studded with icebergs. It was raining, an increasingly common occurrence in summer in this rapidly warming part of Antarctica.

Around 3 p.m., Pitman spotted several of the distinctive triangular dorsal fins of killer whales two miles ahead. Soon, roughly 40 killer whales appeared on all sides of the cruise ship, the National Geographic Explorer, delighting the nearly 150 passengers on board.

Pitman and Durban stepped into a rubber Zodiac driven by a ship’s naturalist and cruised slowly toward the whales. Two large female killer whales approached, rolled on their sides, and “took a long look at us with wide open eyes as they passed a few feet under the Zodiac,” Pitman later recalled. One of the females surfaced next to the boat, and Durban, cradling a black crossbow, fired a satellite tag onto the middle of the whale’s dorsal fin. When the second female rolled on the surface, Durban fired a dart that would provide a tissue sample for scientific analysis. “Our skin donor,” Pitman said later.

Thus began more than a month of killer whale research in the Antarctic, conducted by two of the world’s leading experts on these top predators, whose killing power, Pitman says, “probably hasn’t been rivaled since dinosaurs quit the earth 65 million years ago.” I was a lecturer aboard the Explorer, and was able to watch the pair work for more than a week in the Antarctic.

Three years ago, farther south along the western Antarctic Peninsula, Pitman and Durban spent three weeks observing such behavior among a group of pack ice killer whales, also known as large type-B Antarctic killer whales. The men studied a hunting technique known as “wave-washing,” in which a pod of whales moves through ice floes, its members lifting their heads out of the water — a behavior known as “spy-hopping” — looking for their preferred meal: fat, fish-eating Weddell seals. Once they spotted a seal on an ice floe, the whales called in reinforcements and, two to seven abreast, swam toward the floe and washed the seal off the ice by creating a large wave with powerful strokes of their tails. Pitman and Durban then observed what they call the “butchering” of seals, with the whales first drowning the seals and then meticulously stripping off their skin to get at the choice flesh.

“It was shocking to see,” said Pitman. “You’re not used to animals doing things that are so canny.”

Read rest of story: Environment 360

 

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