The New Student's Reference Work/Birds of Passage

Birds of Passage are birds which are migratory, passing regularly with the seasons from one climate to another. Birds which breed in the United States and go south in the fall, returning to the north in the spring, are called summer birds of passage; while the wild geese which breed in the Arctic regions and visit the United States in autumn, flying north again in the spring, are winter birds of passage. Most of the migratory birds of the western United States pass the winter in Mexico. Birds of the eastern states winter in the south, West Indies, Central America and even (Bobolinks) in Brazil.