Many birds travel thousands of kilometers each year without getting lost. For ma years, scien wondered h they co find th way s accurately. Rese has sh that bi use sev different clues. Some follow the position of the sun during the day or the stars at night. Others appear to sense the Earth's magnetic field, which works like an invisible compass. Young birds may also learn routes by following older members of their group.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.