Bird of the Sun

The Arctic tern is known to make the longest annual migration in the animal kingdom. During its breeding season,
it is found far to the north where summer days are long, and it winters far south in the southern hemisphere,
where the days are longest during November to February.
This means that the Arctic tern probably experiences more sun light during a calendar year than any other creature on Earth.
The long-distance travel of the Arctic tern is well-known both amongst researchers and in the broader public.
Now, for the first time, technological advances allow us to follow the Arctic tern on its immense journey,
practically from pole to pole.

This study used miniature archival light loggers (geo-locators) to map the migration route of the Arctic tern.
The method itself is not novel, and has been used successfully for more that a decade, but due to the weight of loggers,
studies were limited to large-sized seabirds, such as albatrosses and shearwaters.
Within the last couple of years, however, technological development has allowed these loggers
to be reduced in size and weight, opening up a whole new array of small to medium-sized birds to such study.


Greenland Institute of Natural Resources.

Interpolated geolocation tracks of 11 Arctic terns tracked from breeding colonies in Greenland (n = 10 birds)
and Iceland (n = 1 bird).
Green = autumn (postbreeding) migration (August–November),
Red = winter range (December–March), and
Yellow = spring (return) migration (April–May).
Two southbound migration routes were adopted in the South Atlantic, either (A) West African coast (n = 7 birds)
or (B) Brazilian coast. Dotted lines link locations during the equinoxes.

The researcher team, from Greenland, Denmark, the United States, Great Britain, and Iceland, have
successfully mapped the impressive migratory movements of the Arctic tern. The results of the study verify
what has been supposed for decades: that the Arctic tern does indeed conduct the longest annual migration
in the world. Every year this small seabird travels an average of around 71,000 km roundtrip from
Greenland to the Weddell Sea, on the shores of Antarctica, and back to the breeding grounds in Greenland.

In order to equip Arctic terns with geo-locators the bird had to be trapped on the nest. Breeding Arctic terns were trapped during incubation in 2007, and caught again in 2008, after a full circle of migration.

The research results not only confirm the Arctic tern as the champion of long-distance migration, but also
held a few surprises in store for the research team. It turns out that the birds do not immediately travel
south, but spent almost a month at-sea in the middle of the North Atlantic Ocean, approximately 1,000 km
north of the Azores. After this lengthy stop over, the birds continued their long journey south down the
coast of northwest Africa, but around the Cape Verde Islands the birds behaviour surprised the researcher
team again. Approximately half of the birds continued down the coast of Africa, while the other half crossed
the Atlantic Ocean to follow a parallel route south down the east coast of South America.

All of the birds spent the northern winter months in Antarctic waters. Interestingly, on their long return
journey the birds did not choose the shortest route back to their breeding grounds in Greenland. Instead, the
Arctic terns traced out a gigantic „S? pattern northward through the Atlantic Ocean – a detour of several
thousand kilometres over a straight line north to their breeding colonies.

Text and pictures in this frame from http://www.arctictern.info/
"The Arctic Tern - Migration Project"

Unlike gulls, terns feed almost exclusively on fish and krill. South American tern breeds on Tierra del Fuego and the Falklands; Antarctic tern - on islands further south. They fiercely protect their nest, attacking trespassing people. Very similar Arctic tern, Sterna paradisaea, comes from the Northern hemisphere during Austral summer. It has the longest migration route of any bird.