AS our small group of journalists and scientists steps from a rubber Zodiac boat onto Torgersen Island, a party of local Antarctic residents - Adelie penguins - come sledding down the snow-covered hill on their stomachs, like a squad of high-speed bobsledders.
Once up on their pink webbed feet, the penguins waddle about like a convention of diminutive Charlie Chaplins. Soon, however, they get down to business.
All of them start to poke up and down the shoreline, looking for the perfect small black stones they use in building their nests. With prized pebbles selected and safely clamped in their beaks, they march sure-as-soldiers back up the hill to their crowded rookery.
At the top, a band of lazy opportunists in the flock - hoping to escape the laborious task of nest building - waits in ambush. As the industrious penguins try to thread their way through the colony, they are poked, prodded, and pecked by the would-be bandits, in hopes that they will drop their treasured rocks.
Often when one penguin drops his stone fending off an attacker, a second thief appears, grabs the stone and runs off with the bounty.
Here on Torgersen Island, family matters are the penguins' top priority this time of year. This is an egalitarian society; males and females share tasks evenly.
Neither penguin feeds until the pair has finished building the nest and the female has laid her two pale green eggs. She then heads out to sea to feed - primarily on krill and Antarctic silverfish.
``The male stays there to begin the first incubation shift,'' says William Fraser, a penguin researcher and professor at Montana State University in Bozeman. ``He's on there for four to five weeks where he doesn't eat a thing. Then the female returns and takes over.''
Penguins seem to be able to adapt to whatever Mother Nature throws their way. The morning after our first visit, frigid winds were holding steady between 75 and 90 m.p.h. The entire colony of penguins flopped down on their stomachs, squeezing tightly together to let the icy air slip over their streamlined bodies.
``These birds do not begin to feel intense cold until it gets down to minus 40 degrees,'' says Professor Fraser, who has 17 years' research experience on the ice in Antarctica. Penguins ``are unbelievably well insulated,'' he says.
``I've seen spring blizzards come through that will cover hundreds of penguins,'' Fraser says. ``You don't see any penguins in the binoculars, then all of a sudden these heads start popping up. They will not move off their nests.''
But Fraser and his colleague Brent Houston see a climatic warming trend on Antarctic Peninsula that has set off alarm bells in many parts of the environmental community.
``And though global warming has been the buzzword of the late '80s and early '90s, it looks as if this trend began in about 1945,'' Fraser says.
In colder years, sea ice extends far beyond the shores of the Antarctic continent. ``There used to be 4 out of 5 years of heavy sea ice,'' Mr. Houston says. ``Now we're seeing that 1 to 2 out of 5 years are heavy.''
Researchers have found that the well-being of penguin populations is determined in large part by the sea-ice patterns. Some species handle the changes better than others.
``Adelie penguins do better in a broad sense when there is more pack ice,'' Houston says. ``They winter over more successfully, because ice is used for resting, avoiding predators, and [as] a food source because krill are associated with pack ice.''
On the other hand, Chinstrap penguins (so called because of a stripe around their heads) do better with less sea ice. ``Animals that are more open-water species, such as Chinstrap penguins, fur seals, and a lot of sea birds, seem to be increasing,'' Fraser says.
The United States National Science Foundation has established a group of projects called the Long-Term Ecological Research network to make baseline assessments of environments, including Antarctica's, so that scientists can see how changes in populations, pollution, and climate fit into a long time frame.
Penguin chicks in Antarctica have a role in that effort. ``When these chicks grow up, the day before they leave the colony, we go down to the beach and weigh the ones we have banded,'' Houston says. ``Then we can correlate those weights a few years later with how many come back to breed and what condition they are in. Of course you have ice data for those years as well. So we can put it all together.''
In another indication of a warming trend here on Antarctica, other species seem to be expanding their ranges, researchers say. ``Southern fur seals seem to be moving south,'' Houston says. ``Some of the penguin species are also sporadically showing up in higher latitudes [further south].''
Birds other than penguins use the area around Torgersen Island for breeding as well. South Polar skuas, gull-sized brown-and-white predators, fly down from the north just about the time penguin eggs are being laid. Along with Antarctic silverfish, they dine happily on penguin chicks and eggs if they can get them.
Fraser, Houston, and others are watching to see how new sea-ice patterns affect other animals. ``We're seeing a rather marked change,'' Fraser says. ``Many species seem to correlate with this warming trend.''