Some European birds delay migration due to warmth

Some European birds have failed to fly south for the winter,
apparently lured to stay by weeks of mild weather that experts widely
link to global warming.

Birds including robins, thrushes and
ducks that would normally fly south from Scandinavia, for instance,
have been seen in December -- long after snow usually drives them
south. And Siberian swans have been late reaching western Europe.

"With
increasing warmth in winter we suspect that some types of birds won't
bother to migrate at all," said Grahame Madge, spokesman of the British
Royal Society for the Protection of Birds (RSPB).