New Zealand research scientist Peter Wilson said the ice blockage "is a very serious event for these colonies." Penguins breed for the first time at three years of age.

Wilson expected the Cape Royds chicks would hatch but die of starvation and the bulk of the Cape Bird chicks could die.

"It could all fail . . . and more than 50,000 souls will have gone west again," he said, referring to penguins.

Wilson, New Zealand's project leader for the study of the four Adele penguin colonies in the region, said he was sure all the colonies would survive — though their numbers could decline by up to 70 percent.

Antarctica New Zealand is working with the United States and Italian Antarctic programs on alternatives for receiving vital fuel supplies for their science bases in late January.

A U.S. icebreaker, fuel tanker and cargo ship plus an Italian cargo vessel are due to deliver a year's supply of fuel and food at that time, he said.

The alternatives are to break an 80-mile channel through the pack ice to reach Winter Quarters Bay on the McMurdo Sound coast — or offload the fuel and other supplies on the ice edge, pumping fuel through temporary lines several miles to storage tanks, he said.

All Antarctic bases have contingency supplies of a year's food and fuel, Sanson said.

The iceberg is located between McMurdo Sound and Franklin Island to the south and is moving north toward the sound at about 1.2 miles a day. The concern is it will stick on the Ross Ice Shelf, which forms part of the sound and stay there, causing still more problems.

The iceberg is a remnant of one that broke off the Ross Shelf in 2000. That one measured about 4,400 square miles, the size of the Caribbean island of Jamaica, and was the largest iceberg ever recorded.