19 February, 2002
A TALE OF THREE PENGUINS
When people think about Antarctica, they usually think about penguins. There are many species of penguins. Some are more commonly found in the Weddell Sea or the Ross Sea. Others are more common to the Antarctic Peninsula where Palmer Station is located.
Three species of penguins have been seen around Palmer Station this summer: the Adelie, the Chinstrap, and the Gentoo penguins. These three penguin species are beginning to tell an interesting story about climate change.
Scientists have studied penguins and other seabirds here for many years. They study their growth and their health. They study where these birds can be found. They study the numbers of penguins coming back to the islands to breed. These scientists have found some important results. Chinstrap penguins have become more abundant. They have also expanded their territory southward along the western side of the Antarctic Peninsula. Adelie penguin populations have declined around Palmer Station. Adelies have been decreasing steadily in other parts of the Antarctic Peninsula as well. (The Adelie penguin has been studied in Antarctica for more than fifty years.
Here is a little background information.
The adult Adelie penguin is dependent on the sea ice for survival. These penguins do not hunt for their food at night. In the wintertime, the Adelies need to find sea ice. They use the ice as a platform from which to come and go for food. They haul out onto the ice for the night. At first light, the Adelies go back into the water to feed.
In the summertime, the Adelie adults can be found on the rocky islands around Palmer Station. Parents in a breeding pair will take turns going out to forage for krill and fish. This is the food that is fed to the chicks. When the chicks fledge, the adults leave to forage for food to feed themselves. They head into the sea ice. They they follow the sea ice as it moves on.
So, when there is a change in the location and amount of winter sea ice, there is a change in the location of Adelie penguins.
The Chinstrap and Gentoo penguins thrive on the availability of open water in winter. It isn't clear to scientists yet just why they do well in the open water. Scientists think it may be because the open water helps them in their hunt for prey. Chinstraps and Gentoos can eat fish. Gentoos dive deeply, and can find different fish to eat. Chinstraps can spend the winter night at sea. They don't have to find ice to sleep on. Perhaps that means they also can avoid leopard seals by avoiding the sea ice. A lot more has to be known about the Chinstrap and Gentoo penguins.
Bill Fraser is the science team leader for the seabird group. Bill is an ecologist, studying the habitat of this area. He has studied the seabirds here for over twenty-five years. Bill says that seabirds give scientists a window into understanding how the "system" (ecosystem) works. He has observed changes in the seabird population over this time. In 1992, Bill and others wrote an arcticle that was published in the journal, Polar Biology. (Polar Biology, 1992. 11: 525-531). The scientists suggested that the increases in Chinstrap penguin population and distribution in the Antarctic Peninsula was brought on by environmental warming. Scientists have measured a gradual decrease in the number of cold winter years. This change (an increase in the mean winter temperature by 4-5 degrees C in the last 50 years) has resulted in a decrease in winter sea ice cover.
These changes in the sea ice affect the plants and animals. Adelies don't have as much of the winter sea ice to live on. Chinstrap and Gentoo penguins have more open water. Is the habitat is becoming more favorable for the Chinstrap and Gentoo penguins, and less favorable for the Adelie penguins? The research is continuing, but looks like that may be the tale of three penguins.
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