Two species that often cause confusion in Antarctica are the Antarctic Tern and its Arctic counterpart, the Arctic Tern. I guess everybody knows the story of the incredible migration of the Arctic Tern, breeding in the Arctic and wintering in Antarctic waters, flying around 70.000km a year. Many birdwatchers that come and visit the Antarctic Peninsula hope to see a wintering Arctic Tern. However, this turns out to be very difficult.
At first sight, it looks easy: Antarctic Terns have their summer plumage and Arctics their winter plumage. When I first came to Antarctica, I thought every tern with a white forehead (as they have in winter plumage) would be an Arctic Tern. Until I realised that first summer Arctic Terns also had a white forehead when I saw them in summer on Spitsbergen. And if the Arctic Tern would have a first summer plumage, so would the Antarctic.
Now there isn’t much literature comparing Arctic and Antarctic Terns in Antarctica, so it was getting a bit difficult now. After many discussions with fellow birdwatchers who have worked with me on the Antarctic Peninsula and having looked at many ‘winter plumage-type’ terns, I think the Arctic Tern is a great rarity on the Peninsula. I’m not doubting that Arctic Terns winter in Antarctic waters, but they don’t seem to be present on the Antarctic Peninsula.
Antarctic Terns do also migrate but don’t have the long migration of the Arctic Terns. They usually stay on the southern hemisphere and can be seen in South America and South Africa.