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 Scientists on Tuesday documented how this songbird that weighs
half an ounce (12 grams) completes an arduous nonstop flight over
the Atlantic Ocean from forests in New England and eastern Canada to
Caribbean islands as it migrates each fall toward its South American
wintering grounds.
By placing miniature backpacks with geolocators on the birds, the
researchers determined they flew an average of nearly 1,600 miles
(2,540 km) over two to three days.
"No other bird this size migrates for this long in one go. It is
truly one of the most amazing migratory feats ever recorded," said
ecologist Ryan Norris of the University of Guelph in Ontario,
describing "a fly-or-die journey."
They landed in Puerto Rico and Hispaniola, resting for a couple of
days to a couple of weeks before flying to Colombia and Venezuela.
University of Massachusetts ecologist Bill DeLuca described the
migration as "on the brink of impossibility."
 The spring return flight follows a predominantly overland route
through Florida and up the U.S. East Coast.
The research resolves a half-century mystery about blackpoll warbler
migration. There had been indirect evidence they were performing
this transoceanic migration - for example, blackpolls landing on
ships in the Atlantic under bad weather conditions.
But could they really complete such a journey considering a water
landing would kill them?
"Some doubted that such a herculean flight would be physiologically
and physically possible for a songbird weighing one-half ounce,"
said Vermont Center for Ecostudies ornithologist Chris Rimmer.
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Ocean birds including albatrosses and gulls make transoceanic
flights, and tiny ruby-throated hummingbirds cross the Gulf of
Mexico, although that is not as far. Most migratory songbirds that
spend winters in South America fly a safer overland route through
Mexico and Central America.
Blackpolls, with 8-inch (20 cm) wingspans, have distinctive yellow
legs and are speckled with black, white and gray feathers with two
white wing stripes, a white chin and cheeks, and a black "cap" atop
the head.
Before migrating, they gorge themselves to build strength and shrink
many of their digestive organs to minimize any part of the anatomy
not needed during an extended flight.
"They nearly double their body mass in fat reserves and absorb many
non-essential organs during migration to become lean, mean flying
machines, with a little help from southerly trade winds," DeLuca
said.
The research appears in the journal Biology Letters.
(Reporting by Will Dunham; Editing by Sandra Maler)
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