Why do birds migrate? scientists did not have a solid explanation on how or why do birds migrate, but based on discoveries and technology, scientists determine that birds migrate from one place to another depending on the seasons. When it is cold, they migrate from colder temperature to warm places and they also avoid dry places where it does not rain often. When migration season happens in North America, birds have the tendency to move from North to South direction. It is known that most migratory birds breed in the south and returns to the north because of warmer weather, better resources such as food, and mates to help them prepare for breeding season. The two major seasons that birds migrate are spring and fall. However, during the winter most birds die because of the cold, diseases or starvation, and that is why some birds reproduce many offspring in a year. Migration is the most efficient way for birds to survive and reproduce.