What is the breathing of birds?

Birds have nine air sacs. When they take air through the grain, it goes to the largest air sac, which is located at the base of the bird. From there, the air is transported to other air sacs, each of which acts as a siphon to push air flowing in an unusual direction through the lungs.

The lungs of birds are designed to exchange much more oxygen than the lungs of mammals. When the bird takes a second breath, air in the lungs is absorbed into the cranial-air sacs – the caudal, thoracic, cervical and clavicular sacs. The cranial air sacs act as a containment chamber that allows a slight backflow of air to the lungs.