Orientation of passerine trans-Sahara migrants: the directional shift ('Zugknick') reconsidered for free-flying birds

► Flight directions of European passerines along the western flyway to Africa. ► Testing orientation mechanisms based on field observations. ► Gradual shift of migratory direction until the end of Sahara crossing. ► Change of migratory direction after the Sahara crossing. ► Results from laboratory orientation experiments reconsidered.