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2011-06-15 Arctic tern's epic migration - longest animal migration.
Arctic Tern - Sterna paradisaea
A new study adds surprising new detail to the Arctic tern's epic migration.
The Arctic tern's extraordinary pole-to-pole migration has been detailed by an international team of scientists.
The
researchers fitted the birds with tiny tracking devices to see
precisely which routes the animals took on their 70,000km (43,000 miles)
round trip.
The study reveals they fly down either the African
or Brazilian coasts but then return in an "S"-shaped path up the middle
of the Atlantic Ocean.
The Arctic Tern's
annual migration from Arctic breeding grounds to the Southern Ocean may be the longest seasonal movement of any animal.
The tracking of 11 Arctic terns
fitted with miniature (1.4-g) geolocators revealed that these birds do
indeed travel huge distances (more than 80,000 km
annually for some individuals). As well as
confirming the location of the main wintering region, it also identified
a previously
unknown oceanic stopover area in the North Atlantic
used by birds from at least two breeding populations, from Greenland
and
Iceland.
Although birds from the same colony took
one of two alternative
southbound migration routes following the African or South American
coast, all returned on a broadly similar, sigmoidal
trajectory, crossing from east to west in the
Atlantic in the region of the equatorial Intertropical Convergence Zone.
Arctic terns clearly target regions of high marine productivity both as stopover and wintering areas, and exploit prevailing global wind
systems to reduce flight costs on long-distance commutes.
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