Bird migrations are likely to get longer according to a study of the potential impacts of climate change on the breeding and winter ranges of migrant birds.
The findings from a team of scientists led by Durham University in the UK indicate that flights undertaken by birds to spring breeding grounds in Europe could increase by as much as 250 miles for some species. The research team, funded by the Natural Environment Research Council and the RSPB, looked at the current migration patterns of European Sylvia warblers, a group of birds that are common residents and visitors to Europe. Published in the Journal of Biogeography, the report says there is evidence that breeding ranges will shift northwards in the future, while the wintering ranges will remain stationary for many species Some 500 million birds are estimated to migrate to Europe and Asia from Africa; birds as small as 9 grams undertake the annual migration of thousands of miles between the two continents to find food and suitable climate. Birds have to put on a large amount of weight as fat before migrating long distances; they even shrink the size of some of their internal organs to become more fuel efficient. Some species must double their weight to have enough energy to undertake the huge journeys.
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“Most warblers come [to the UK] in spring and summer time to take advantage of the surplus of insects, and leave for warmer climes in the autumn. From 2071 to 2100, nine out of the 17 species we looked at are projected to face longer migrations, particularly birds that cross the Sahara desert,” said Dr Stephen Willis of Durham University in a press statement. The impact of longer migration flights could be potentially disastrous for some species. “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,” said Willis. Co-author of the research paper, Professor Rhys Green of Cambridge University and RSPB commented in the Journal of Biogeography: “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 refueling on migration could mean the difference between life and death.” The research predicts that some species that fly long distances (on average 2,800 miles to 3,700 miles), are likely to face significantly longer flights, up to 250 miles longer, and shorter distance fliers may face journeys of up to 125 miles longer. Dr Willis believes that birds are facing the biggest threat to their survival since the Ice Age. “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. 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,” he said.