"Penguin Ranch" Reveals Hunting, Swimming Secrets

James Owen
for National Geographic News
January 30, 2004

Harnessed up and ready to dive, the fat penguin looks as though it has its own mini scuba tank. Of course, emperor penguins don't need scuba tanks—they are bird-world record holders at holding their breath underwater. The device strapped to its back is, in fact, a Crittercam, one of National Geographic's animal-adapted camera systems.

It was attached by marine biologist and medical anesthesiologist Paul Ponganis, to provide, for the first time, a bird's-eye view of emperor penguins (Aptenodytes forsteri) as they hunt beneath the ice.

Ponganis, from the Scripps Institution of Oceanography in La Jolla, California, is trying to fathom out why the bird is such an amazing submariner.

For instance, why is it that emperor penguins can stay submerged for almost half an hour, longer than any other bird? And why are they able to dive well over half a kilometer down (more than 1,500 feet), far deeper than any biologist thought possible?

These are life-or-death questions, says Ponganis. Not just for penguins, but also for many critically ill humans whose lives could possibly be saved if scientists can discover the answers.

The penguins Ponganis works with live at his "Penguin Ranch," 20 miles (32 kilometers) off Ross Island, on frozen McMurdo Sound. Up to a dozen local birds are kept here temporarily before being allowed to waddle back to the wild. Their wooden fenced corral includes two dive holes. Isolated by miles of sea ice, the birds have no choice but to return to these holes after each hunting foray.

Ponganis says Crittercam doesn't impede the penguins significantly underwater, though the increased drag starts to slow them down after an hour or so. A video monitor back at the ranch shows them diving to 165 feet (50 meters) where they cruise around before accelerating towards the surface as they zero in on sub-ice fish (Pagothenia borchgrevinki). Up to six fish are caught during each dive.

"As far as I know, it was the first time feeding in the wild by an emperor penguin was actually recorded," said Ponganis, now back in California. "Documentation of this behavior was valuable because it demonstrated that even shallow foraging dives could be successful, and that the isolated dive hole is our best model for studying diving physiology."

Colleague and Antarctic veteran Jerry Kooyman, research professor at the Scripps Institution of Oceanography, was similarly thrilled with the Crittercam footage. Kooyman, a leading authority on what he calls the "icon of Antarctica," says he was surprised by the penguins' hunting success rate, and the distance at which they spotted their prey.

Biggest Penguin

Growing to over 3.8 feet (1.15 meters) tall and weighing up to 88 pounds (40 kilograms), emperor penguins are the largest of 17 penguin species. Some 200,000 pairs breed in colonies scattered across Antarctica. They are the only animals to breed here in winter. Chicks fledge in summer, when food is abundant and the weather relatively mild.

A single egg is incubated by the male while its partner heads for the sea. With the egg tucked carefully between its feet and belly, the bird huddles together with other males for warmth. They must survive horrendous gales and wind chill temperatures down to minus 76°F (minus 60°C) from the start of the breeding season until the females return. That's about four months, and without any food.

Continued on Next Page >>


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