Why are swallows migratory birds?

Migratory birds refer to birds that migrate periodically with different seasons. Many birds have the characteristics of seasonal migration along latitude. In summer, these birds breed in temperate regions with higher latitudes, and in winter, they spend the winter in tropical regions with lower latitudes. In late summer and early autumn, these birds move from the breeding ground to the wintering ground, and in spring, they return to the breeding ground and fly north. These birds that migrate north and south with the seasons are called migratory birds.

Swallows have this habit, so they are migratory birds.