The timing of migration seems to be controlled primarily by changes in day length. Migrating birds navigate using celestial cues from the sun and stars, the earth's magnetic field, and probably also mental maps. COUNT 4
QSN1 What causes the timing of migration? ANS1 changes in day length QSN2 How do migrating birds navigate? ANS2 celestial cues from the sun and stars QSN3 How else to migrating birds navigate? ANS3 the earth's magnetic field QSN4 What might help migrating birds navigate? ANS4 mental maps