Many thousands of birds of all types will take to the wing and FLY to their wintering grounds. In fact, some birds don't even fly south at all. The redhead, a common diving duck, may migrate from Utah to the East Coast for the winter. Harlequin ducks fly west from their nesting grounds in the Rockies to the Pacific. Other birds follow an altitudinal migration route.
Avian migration is largely about food availability.
Today, this idea is something of a foregone conclusion. It seems obvious to us that these birds migrate to the tropics or that other species migrate to Southeast for the winter. However, in the past, our perception of bird migration was quite different. Aristotle claimed that swallows, storks, dippers, doves, and larks all hid in holes in the ground and hibernated for the winter. He also believed that birds were capable of transforming themselves, asserting that the European redstart metamorphosed into a robin.