Charting a penguin's progress


Rookery: A thriving colony of birds suggests the ecosystem of Antarctica is changing.

February 06, 2000|By Douglas Birch | Douglas Birch,SUN STAFF

CAPE ROYDS, Antarctica -- As gale-force winds strafe the icy waters of McMurdo Sound, a leopard seal cruises through the whitecaps gnawing on an Adelie penguin. Four other birds dart through the waves toward shore and safety.

On a hill, Hannahrose Nevins, a 30-year-old biologist, braces herself against the gusts and furiously jots notes in her field journal. It is the first leopard seal attack here that researchers can recall -- and another signal that the Cape Royds colony is changing.

This, the world's southernmost penguin rookery, was once a tiny frontier hamlet. But in the past two decades, the number of Adelies here has risen 300 percent, to about 4,000 breeding pairs. Now, there may be enough birds to support one of these predatory seals, the crocodiles of the Antarctic.

Most of the world's 17 penguin species are under pressure from oil pollution, overfishing and human encroachment. African penguins numbered 2 million adults at the turn of the century. Now there are about 180,000, and their population continues to slide. But here -- living just on the fringe of the Earth's coldest, driest and windiest continent -- the Adelie are thriving. Researchers want to know why.

Nevins, a graduate student at Moss Landing Marine Laboratories in Monterey, Calif., and Michelle Hester, 31, a bird biologist from the San Francisco Bay area, started camping out on the rocks here in mid-December.

Cape Royds penguins are familiar with humans. Their rookery is about 100 feet from the wooden hut erected by Sir Ernest Shackleton during the British explorer's unsuccessful 1908-1909 expedition to the South Pole. (Shackleton's party hunted and ate the Cape Royds Adelie. The penguins retaliated by standing just out of reach of the expedition's tethered sled dogs, tormenting them.)

Out in the colony, feathers swirl in the wind. Birds amble over the rocks, stained pinkish by guano. They loll on their bellies, napping. Mostly, they gather in tight little bunches around fluffy juveniles, caterwauling: "Awh-awh-awh-awh-AWH." The din is relentless. "At 4 a.m. it generally gets quiet," Hester says. But not always.

To study the bird's movements, researchers have embedded computer chips under the skin of about 35 birds. Periodically, the humans use plumber's tape to fasten data recorders and transmitters to the feathers of a few of the birds.

The scientists have built a corral of orange plastic netting around 180 of their nests, with a single entrance. As a bird passes, electronic devices record the penguin's identity, its weight and whether it is headed in or out.

The Adelies don't seem to mind all the scrutiny, Hester says. Birds raised inside the netting don't seem to do any better or worse than those outside. Neither do the study birds always cooperate. "Our data gets a little squirrelly when the chicks stand together on the scale," Hester says, as wind claws at her parka.

She transfers data from the gate to her portable computer, then circles the penguin corral, counting chicks. A juvenile male, curious but wary, toddles up. Like all of the Adelies, his electric blue eyes are set in circles of white, giving him a startled look.

Birds returning from foraging waddle up the slope from an ice-covered bay. Their wet coats glisten, and their bellies sag with fish and shrimp-like krill. They're so fat, they seem in danger of tipping over. But their ungainly appearance is misleading.

"It's a whole 'nother thing to watch these guys in the water," Hester says. "They come to life out there. The first time I saw penguins porpoising in the water, it looked so effortless."

Every season, female Adelies lay two eggs in a nest built of rocks. So adult birds spend a lot of time hunting for walnut-sized rocks to build their nests. Decent rocks quickly become scarce, resulting in squabbles and even thefts. Fiona Hunter, a zoologist from Cambridge University, studied Ross Island birds and found that some females accepted rocks from males in return for sex -- a behavior that the tabloid press labeled "penguin prostitution."

It is late in the season now, the chicks are several weeks old, and the market for rocks has crashed. Still, juvenile males are busy collecting rocks and building nests. It's not clear why. These lonely adolescents look pathetic. Their white breast feathers are stained with vomit or guano because they seldom bother to swim out to forage.

Adults lead lives similar to those of human parents. They arrive home exhausted after their long commute, greet their spouses and try to cope with the urgent demands of their slump-shouldered offspring.

The biggest threat Adelie chicks face is the South Polar skua, a hulking, mottled bird that resembles a gull. To protect themselves, the chicks huddle together in tight little bunches that resemble Russian fur hats. Adults stand sentry on the edge of these bunches. With relatively few adult birds, Cape Royds' chicks are highly vulnerable to skua attacks.

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