Some European birds will have to fly further as global warming shifts their breeding grounds northwards in the biggest challenge to the tiny migrants since the Ice Age,, scientists said on April 15.
Some types of warbler would have to add 400 kms (250 miles) to twice-yearly trips up to 6,000 kms to and from Africa, according to the report which said it was the first to examine the potential impact of climate change on avian migration.
"For some birds the extra distance might make the difference between being able to make it or not," Stephen Willis of Durham University told Reuters of the study he led with a team of British-based scientists.
The report, adding to projected threats to animals and plants from global warming, said an estimated 500 million birds migrate from Africa to Europe and Asia every year. Some weigh just 9 grams (0.3 ounces).
Nine of 17 warbler species studied would have to fly further under projected warming by 2071-2100, especially the whitethroat, the barred warbler or the Orphean warbler that cross the Sahara Desert, according to the study in the Journal of Biogeography.
"Some species may be able to adapt and change, for example by adopting shorter migration routes, if they can find enough food at the right time," Willis said in a statement. Some blackcap warblers in Germany had dropped winter flights south.