Birds tend to migrate along four major routes in North America called flyways , which are depicted below. A Lesser Yellowlegs banded in Massachusetts was recovered in the West Indies - 3000km or 600km per day. More recent studies with radio tracking give us some additional information. There is often a relationship between food habits and migration. Insects become scarce in the winter in northern latitudes, so insectivorous birds must move closer to the equator where insects are more abundant.
Insectivorous birds are the largest group of migrants.
Some insect-eaters, such as chickadees, can eat seeds in the winter and thus do not tend to migrate. Fruit-eating birds may not have to migrate as far because fruits are generally available at the edge of the temperate zone. And seeds are available all year around in most areas, so seed-eaters tend not to migrate. But seeds are not produced in the winter and may be covered by snow, forcing birds southward, or at least down the mountains. Fish-eating birds may be cut off from their food supply when northern lakes freeze over, but can generally overwinter if the lake doesn't totally freeze over.