Northernmost Emperor Penguin Colony Gone, Though Scientists Cautious On Causes

A small colony of emperor penguins on an island off the West Antarctic Peninsula is gone, and the most likely culprit is loss of sea ice caused by warming. Although it has been predicted that penguins could suffer greatly because of global warming, this is the first time the disappearance of a colony has been documented. The researchers, however, caution that their study is hampered by a lack of long-term information on emperor penguins, both at this site and in general, and their environment.

Emperor penguins are regal, if bulky, birds that stand as high as 4 feet (1.2 meters) and can weigh as much as 84 pounds (38 kilograms). This colony, first spotted in 1948 on an island dubbed Emperor Island, was a small one that had approximately 150 breeding pairs. Observations are spotty, but the populations appear to have been relatively stable until the 1970s. A report in 1978 showed a sharp drop in population, a trend that continued until an airplane survey found the island empty in 2009.

This raises the question: Did the penguins die off or just relocate? "That's one of the big unknowns," said Philip Trathan, the lead researcher and head of conservation biology at the British Antarctic Survey.

Emperor penguins appear to return home each year to the site where they hatched. But the colonies must sometimes relocate because of changes in the ice, however, the details of how this happens aren't understood. Trathan and his colleagues speculate that the Emperor Island penguins born in the late 1970s – they live to be about 20 years old – may have continued to return in smaller numbers each year until the colony disappeared. Ice is crucial to these birds. Most emperor penguins breed on sea ice — called fast ice — which attaches to the ice shelves and coastlines, and does not move in wind or currents. As the ice develops in autumn, the birds gather at their colonies. They remain there, mating, laying eggs and raising chicks until mid-summer, when the chicks fledge and the fast ice breaks up. They also forage within the pack ice, which floats at the surface of the water.

EDIT

http://news.yahoo.com/s/livescience/20110307/sc_livescience/thelostemperoracolonyofpenguinsdisappears

few years ago? They had never done that before. I cannot remember the details but it was posted here on DU.

nt