THE Scottish border town of Gretna Green has an influx of visitors, and not just the human kind. It seems locals and tourists alike just can't get enough of watching millions of starlings converge on the sky on sunset as the birds search for a safe place to roost. Hundreds of spectators have been treated to the amazing sunset display, which has left them mesmerised by the huge flock's sweeping aerial acrobatics. Drivers on the A74M, the main motorway between England and Scotland, have been stopping in their droves to witness the sight. But the shear mass of birds is causing a distraction to commuters and truck drivers who are urged to take extra care when pulling over and parking to watch the display. And while it may look like the birds are on a kamakazi mission, the logic behind their aerial acrobatics makes much more sense. Every winter, the birds take to the skies after a long day spent feeding in nearby reed beds. As they take flight during the last minutes of daylight, the starlings fly quick and fast in a bid to confuse waiting predators such as sparrowhawks and buzzards. The tiny birds must converge, fly and sqwark, in an attempt to confuse their predators, reaching speeds of more than 20mph, with few if any crashes. Scientists say the secret behind their amazing spatial awareness is that each starling tracks seven other birds  enabling the group's cohesion. The naturally occurring event is a spectacle which takes place only during the winter months. Starling numbers have halved in the last 25 years and they are now red-listed  as an endangered species. Experts say the starlings are a mix of British and European birds and will leave for Russia in February and March. Nature lover Jon Tait, 34, said: 'It's amazing to see the natural world  like this. The shapes and movements they make are beautiful - Hollywood special  effects couldn't make it more breathtaking. 'Whenever I get the train I have to dive undercover at the station when they come because they leave a bit of a mess, but it's worth it to see them in the sky.          " DM