Dear wwh,

You wrote: When the bird breathes, the air goes all the way through the lung, and into a thing like a condom, so that exchange is maximized.

So, from what you wrote, I gather that there is a second organ into which the air flows? There's the lung plus the second organ? Maybe I should google up a diagram of the bird's respiratory system. And would this be true, too, of flightless birds, such as ostriches? I wouldn't expect so.

I wonder why, when looking at birds, I rarely see them with open mouths? It appears that their tiny nostrils are doing just fine!

Also, thank you very much for telling us about the pipe-under-water impossibility. How could so many movies present such an escape? Interesting.

Best regards,
WW