No, in and out is not how birds breath, and process oxygen. You might want to take a look at this article, it it isn’t too much trouble.
Enlighten us. After the air goes into the bird, where does it go?
Let me help you. From the article: The air, still moving in one direction, then flows from the smaller bronchi into the bypassed airway and then OUT of the lungs, completing a one-way loop.”
Ok, I get the unidirectional lung. What I am saying is that air goes in air goes out, otherwise the bird would puff up and explode. The air does not stay in the bird, it goes out after it goes in.