Birds have different morpholgical adaptations for flight. When in flight, feathers act together as the bird flaps its wings down. When the bird moves its wings up, the feather move apart to grant air to pass through. Hollow bones helps with oxygen intake during flight. Presence of air sacs adds more oxygen to the bird's blood which gives them added energy for flight. Bird wings are adapted to their form of life such as their annual migration that lasts a thousand of miles.
a. adaptations for flight