Polar Meltdown
Is the heat wave on the Antarctic Peninsula a harbinger of global climate change?
On Torgersen Island, about half a mile west of Palmer, Fraser quietly watches and counts the birds as they come and go or tend their nests and their chicks. The chicks are about two-thirds the size of an adult and covered in gray down. But in addition to taking a census of the Adelies, Fraser wants to know what the birds are eating. "You know how the old-timers did this?" he asks. He takes aim down an imaginary rifle barrel. "Plink! I just don't think I could ever do that. No way."
Instead, he and co-researcher Donna Patterson select five of the 18-inch-high Adelies as they hop across the rocks, tummies plump from foraging at sea. After a short chase, they drop a net over each bird, pick it up by the base of a flipper, and carefully measure its skull and beak size. While Fraser grips the bird's torso between his knees, Patterson gets behind him to hold its calloused, sharp-nailed feet. Field assistant and graduate student Erik Chapman dips a clear, flexible tube in olive oil. He passes the tube to Fraser, who with a look of apology on his face, slides it down the penguin's throat. Turning a hand crank, Chapman pumps warm salt water into the bird's stomach. In a moment, the bird regurgitates the water, along with its recent meal.
Stoics. Bird by bird, the researchers fill small plastic bags with disgorged krill, the shrimplike plankton that are the near-exclusive fare of penguins here. Except for a slight pink color from exposure to digestive enzymes and acids, the limp crustaceans look fresh. A pair of brown skuas--powerful predatory relatives of gulls that fly like eagles and often consume stray penguin chicks--alight nearby. They know they'll get some leftovers tossed to the ground by the scientists. As far as can be told, the procedure does the penguins no harm. They endure it with impressive equanimity. Upon release, each scrambles away, flippers flapping, then resumes a deliberate walk back to the colony where mate and offspring wait.
An hour or so later, Bill, Donna, and Erik are back at a lab bench on Palmer's ground floor, picking through the erstwhile penguin meals with tweezers, measuring each of the krill against a ruler. To the untrained eye they don't look ominous--fat and near the 2.5-inch maximum length that these krill reach. But Fraser sees something else. "This looks bad," he says, laying a few krill upon the lab bench's black surface. Such big krill are at least three years old. Young krill depend in their first winter on shelter under the solid ice that forms on the sea surface. The absence of young krill in these Adelies' diet reinforces Fraser's fear that this food source could collapse if winters around here remain as warm and ice free as they have become. Recently, winter ice is getting rarer. At midcentury 4 out of every 5 winters here produced extensive sea ice. Now, just 2 in 5 bring the heavy winter ice necessary to shelter the young krill.
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