Mar 5, 2011 10:54 GMT  ·  By
Emperor penguins are vulnerable to the effects of global warming on the ice shelfs they call home
   Emperor penguins are vulnerable to the effects of global warming on the ice shelfs they call home

Biologists have documented the first instance of what they call the global warming-induced disappearance of an animal colony. The experts can no longer find even the smallest traces of a small colony of penguins that once lived on an island off the coasts of Antarctica.

It has been proposed a long time ago that penguins would be among the most affected species when climate change finally struck, right alongside other ice-dependent animals, like polar bears.

But no one documented an actual case of that happening until now. Experts believe that the emperor penguin colony disappeared because of dwindling sea ices around their home island.

The island in question is located off the West Antarctic Peninsula, which is one of the areas that lost the most ice due to the warming climate. Without the shelfs to provide them with support and food, the penguins most likely could not secure enough to eat.

When the Emperor Island colony was first discovered in 1948, it featured about 150 breeding pairs of penguins. An 1978 report showed a sharp decline in numbers, while a 2009 aerial survey found the entire island deserted.

One of the biggest unknowns in this study is whether the penguins died off, or just relocated to a more hospitable environment, says lead researcher Philip Trathan. He holds an appointment as a conservation biologist as the British Antarctic Survey (BAS), LiveScience reports.

An explanation could be that fewer and fewer emperor penguins returned to this location over the years. The animals live for about 20 years, and they tend to return yearly to the site where they hatched.

Over time, it could be that more and more parents from the Emperor Island colony laid their eggs elsewhere. As such, the new generation did not return to the former colony, because they did not know where it was, and had no connection to it.

On the other hand, the researchers did find a connection to climate change and rising temperatures. “The one site in Antarctica where we have seen really big changes is the West Antarctic Peninsula,” Trathan explains in the February 28 issue of the journal PLoS ONE.

Ices in this region were observed over the past two decades forming about 54 days later than normal, and melting some 31 days earlier. This may have also contributed to the decline of the penguin colony. These birds are completely reliant on ice for most of their activities.

The BAS team admits that more studies are required to establish a clear cause for the penguins' disappearance. “We need to look at more colonies so we can reduce the uncertainty. With the first report, there is a high degree of uncertainty,” the BAS team leader concludes.