Why Mt. Everest climbers long to breathe through their butts ...

[kenny]

I know you've always wondered about this.
The answer is at the end of this article.

How Birds Breathe with their Butts

carnegiemnh.org

 

[Matata]

Birds also have air sacs in their bones. When I was a wildlife rehabber, people would bring in birds with ruptured air sacs usually caused by a cat attack. The air sacs would pop out of the wound and looked like an inflated balloon although they are tissue paper thin. We would have to deflate the air sac to get it back inside the bird (usually through needle aspiration) and used super glue to repair any holes or tears in the sacs.

One day someone brought in a Pelican that had a ruptured air sac caused by a fish hook and was starving because it couldn't dive and stay under water; kept popping up like a cork.

Avians are totally fascinating.