To find out how they do it , ornithologists Johan Bäckman and Thomas Alerstam of Sweden’s Lund University used radar to track the swifts ’ nocturnal movements . As reported by the German science magazine Bild der Wissenschaft , the researchers observed a certain flight pattern that keeps the swifts in position .
To find out how they do it , ornithologists Johan Backman and Thomas Alerstam of Sweden’s Lund University used radar to track the swifts ’ nocturnal movements . As reported by the German science magazine Bild der Wissenschaft , the researchers observed a certain flight pattern that keeps the swifts in position .