There are several important differences in the mechanism and pattern of lung ventilation in birds compared with other vertebrates with lungs.
- The lungs of birds do not inflate and deflate, they stay at the same volume.
- Lungs are also ventilated from all directions through a lot of complex air sacs.
- Lungs are continuously ventilated in a single direction with freshly breathed-in (inspired) air, even when the bird is breathing out.