This is bird note.

Even if you had feathers, lightweight bones and powerful wings, you would still lack something essential to flying like a bird.

The highly efficient breathing anatomy that powers the exertion of flight. The human apparatus of diaphragm and lungs is just not up to the

job. It can't extract enough oxygen to fuel flight.

A bird's breathing anatomy is far more efficient than ours.

It is driven by large, thin-walled air sacks located throughout the body cavity. The air sacks operate like bellows,

first storing and then directing air to create a one-way flow through the bird's lungs.

This parabronquial system for extracting oxygen from the air

has a far greater surface area than the lungs of a mammal, making sustained flight

possible, and birds lack a diaphragm. Instead they inhale and

exhale using special muscles that expand or contract the entire body cavity and air sacs.

The way they breathe allows migrating birds to fly in the thin air thousands of feet above the

earth.

A feat we can only marvel at from below.

For bird note, I'm Michael Stone.