Most birds flap their wings to fly, and even birds that mainly glide flap their wings to take off and land. Powerful muscles in the bird's breast pull the wings up and down. For the downstroke, the primary feathers close together and push the air down and back, thrusting the bird up and forward. For the upstroke, the primaries part to let air flow through as the wings gently rise, ready for another downstroke. Birds such as vultures flap only slowly.
Many birds fly to different places at certain times of year.
This journey is called migration. When winter hits the north, many birds fly far south to the warmth of the tropics where food is more plentiful. Some birds, such as warblers and birds of prey, migrate alone, but birds such as starlings, pigeons and godwits move in vast flocks. No bird flies further than the Arctic tern. This remarkable bird lives in the Antarctic when it is summer there, then flies all the way to the Arctic to catch the summer again - a round trip of 40,000km.