List the flight devices available in the external structure of birds by body division.

Most bird species can fly. For this, they have a number of adaptations. First of all, it is the presence of wings. Some birds are able to glide in the air, which saves energy. Some birds must flap their wings continuously to fly. Birds have the shape of their heads and bodies to have the least air resistance. They can raise their legs while flying to reduce air resistance. This small detail helps to save energy and strength for long flights over long distances.