LOS ANGELES -- 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 last week 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 -- roughly the area of Delaware.
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.