Why birds vanish with the changing seasons remained a mystery until 1822, when a German teenager shot down a white stork with a three-foot Mozambican spear impaling its neck. It was the first important clue in solving the puzzle of seasonal bird migration . . . Migratory birds connect teenagers living on different continents in a way they never could have imagined. Teens across time periods and cultures uncover more clues to unravel the mysteries of bird migration. But birds that once filled the skies are now fighting for their lives.