SPACE.com -- Enormous Icebergs Imperil Penguins Heading For Antarctica Breeding Grounds

The images, taken between December 2000 and December 2001, depict the rapid motion of the C-16 iceberg in late 2000 and early 2001 and its subsequent stall, as well as the incursion of the B-15A iceberg, a large fragment of the original B-15 iceberg. The increase in sea ice is particularly pronounced in the final image.

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	Enormous Icebergs Imperil Penguins Heading For Antarctica Breeding Grounds By Andrew Bridges AP Science Writer posted: 10:43 am ET 28 December 2001

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LOS ANGELES (AP) -- Massive icebergs and an unprecedented amount of sea ice have nearly isolated one of Antarctica's largest populations of Adelie penguins, jeopardizing attempts by the birds to breed, scientists report.

Each year at this time, the penguins flock from their feeding grounds at sea to Ross Island, where they breed and lay their eggs in shallow nests lined with pebbles.

But satellite images released Thursday by NASA show the coast around Cape Crozier, normally home to a colony of about 130,000 breeding pairs of the penguins, is choked with ice and icebergs.

The largest of the bergs, dubbed B-15A, covers 2,100 square miles (5439 sq. kilometers) -- roughly the size of Cyprus.

The amount of sea ice has increased -- and in some cases, doubled -- the distance between the breeding grounds and the open water, where penguins feast on krill, fish and squid. That means the birds must now walk rather than swim to their colonies, which can take them five times as long.

Scientist David Ainley of H.T. Harvey & Associates, ecological consultants based in San Jose, said the numbers of Adelie penguins is on the "low side" at Cape Crozier, threatening the survival of the colony.

The colony, the world's sixth-largest and southernmost population of the penguins, has been studied continuously since 1959. It had been increasing in size in recent years.

A smaller Adelie colony at nearby Cape Royds will "fail totally," Ainley said. A colony of 1,200 Emperor penguins at Cape Crozier also failed to raise chicks this year, according to researchers working on the National Science Foundation-funded study.

Among the natural culprits are B-15A and a smaller iceberg, C-16. The two bergs broke off from the Ross Ice Shelf in March 2000 as part of a natural calving process and have gradually migrated along the shore, altering wind and current patterns in the process.

The bergs may eventually seal off sea access to McMurdo Station, the main U.S. facility in Antarctica, said Ian Joughin, a researcher at the National Aeronautics and Space Administration's Jet Propulsion Laboratory.

The movement of the bergs, and subsequent growth of sea ice in the region, was seen in NASA imagery captured by the agency's Terra satellite.