Swallows migrate from autumn to spring every year because of lack of food, in order to obtain a broader living space. But unlike most other passerine migratory birds, swallows migrate during the day and fly at low altitude.
In addition, they often feed during migration, so their fat reserves are lower than those of other migratory birds of the same size. Species that breed in Africa often migrate with rainfall patterns, but the specific situation is little known. Other species, such as the gray-waisted swallows, seem to wander around without a fixed migration route.