Birds may have to fly an extra 250 miles because of climate change

Published on Tuesday 14 April 2009 22:03

TINY birds that already face epic annual migrations could have to fly up to 250 miles further because of climate change, experts have warned.

The scientists behind the research have said that the extra distance added to already-marathon journeys could be the "difference between life and death" for some birds.

Those likely to be affected include the whitethroat, a warbler about the size of a great tit commonly seen in Scotland during the summer.

It could be forced to travel 3,759 miles from Africa to find a suitable spring breeding ground in Europe, whereas it currently flies an average of 3,417 miles.

The scientists looked at the current migration patterns of European sylvia warblers, a group of birds that are common visitors to Europe.

They used simulation models to show that breeding ranges could shift northwards in the future, while the birds would continue to use their present wintering ranges.

Nine out of the 17 species that they studied would face longer migrations from 2071, the scientists concluded.

Dr Stephen Willis, of Durham University, who led the research, said: "Our findings show that marathon migrations for some birds are set to become even longer journeys. This is bad news for birds like the whitethroat, a common farmland bird. The added distance is a considerable threat."

He added that climate change would present the biggest threat to the birds since the last ice age, the Pleistocene era.

"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," he said.

"Bird migrations are incredible feats of stamina and endurance but, as temperatures rise and habitats change, birds will face their biggest challenge since the Pleistocene era."

About 500 million birds, some weighing as little as 9g, undertake epic journeys of thousands of miles between Europe or Asia and Africa.

Some species must double their weight to have enough energy to undertake the huge journeys.

Professor Rhys Green, of Cambridge University and the RSPB, added: "These tiny birds make amazing journeys, pushing themselves to the limits of endurance.

"Anything that makes those journeys longer or more dependent on rare and vulnerable pit-stop habitats used for refuelling on migration could mean the difference between life and death."

The study, by Durham University, the University of Cambridge and the RSPB, was the first to look at the potential impacts of climate change on the breeding and winter ranges of migrant birds.

It is published in the Journal of Biogeography.