The primary motivation for migration appears to be food; for example, some hummingbirds choose not to migrate if fed through the winter. Also, the longer days of the northern summer provide extended time for breeding birds to feed their young. This helps diurnal birds to produce larger clutches than related non-migratory species that remain in the tropics. As the days shorten in autumn, the birds return to warmer regions where the available food supply varies little with the season. COUNT 5
QSN1 What is the primary motivation for migration? ANS1 food QSN2 Which birds will not migrate if they are well fed through winter? ANS2 hummingbirds QSN3 When do the birds return to warmer regions? ANS3 autumn QSN4 what do the longer days of summer provide the birds? ANS4 time for breeding birds to feed their young. QSN5 What do diurnal birds produce as opposed to non migratory species? ANS5 larger clutches