Bird nests thousands of years old, still being used

The gyrfalcon nest in the photo above is 1,000 years old. It's quite young... compared to the 2,500-year-old nest found elsewhere in Greenland.

Three other nests, each over 1,000 years old, have also been found, one of which contains feathers from a bird that lived more than 600 years ago...

To find out just how long the birds return to the same site, ornithologist Kurt Burnham of the University of Oxford, UK and colleagues decided to carbon date the guano and other debris that birds leave at various nest sites around Greenland...

Carbon dating revealed that one nest in Kangerlussuaq in central-west Greenland is between 2,360 and 2,740 years old, the researchers report in Ibis...