The birds have airbags airbags are connected to the lungs, the air is used to book flights now. When a bird breath air bags expand to on air hose to the air bag parts, and air from the lungs to the front airbags in the target. When you breathe out, the air bags recoil after lung and into the air from the front to the air bag outside. Therefore, each cycle of respiration, so that the air is full of birds will have to breathe in and out.