Guardian: It could be considered an air traffic control system for birds who have flown perilously off course. A wind farm in southern Texas, situated on a flight path used by millions of birds each autumn and spring, is pioneering the use of radar technology to avoid deadly collisions between a 2,500lb rotating blade and bird. US wind farms kill about 7,000 birds a year, according to a recent study. Other studies of individual wind farms suggest a higher toll on bats and birds, who crash into …