"George Patterson" wrote in message
news:f%dbf.2500$SV1.934@trndny01...
Peter R. wrote:

I wonder what gives a goose's lungs the ability to extract o2 at
that altitude?

I would assume they have a different permeable membrane than do humans.

Much more than that going on. Did you get a chance to read the article that
someone posted a link to, about the bar geese? It was good, I thought.

Birds have a neat thing going on with their lungs. While we take in fresh
air, the oxy gets taken up while the co2 gets taken out of the blood, then
we exhale. Not much exchanging goes on as we exhale. Birds don't waste that
portion of time we spend exhaling, but instead have more air being pumped
across the membranes from reserve sacs. It is almost a circular motion type
of breathing, with the possibility of almost double exchange compared to us.
I'm quite sure I don't explain it well, as it is tough to comprehend. (as it
was told to me)

The bar geese have some extra benefits, also, thought to have evolved over
time with the species, and where they migrate. Their hemoglobin is extra
efficient, and their lungs therefore extra efficient.
--
Jim in NC