The migration is under way.

It's south for the winter.

What was a couple of hundred became a couple thousand, then ten thousand as the flock swooped around in short flights gathering their species.

Around an about they swooped and called. Come with us. It's the day. Accurate weather prediction by birds so approaches a storm. The joy of natural life and what would life be like for us were we to fly with ease hither, thither, yon, here, there, gone.

Clothed like flowers, fed like the trees, one great big family, aloft along with the breeze. How do they know as fearless they go to and fro, like schools of fish in the sea. Swimming through the air without so much as a care, as one with the born right to be free. Fearless to what will be, in a new place good and sweet. Bugs and worms, grains and berries, branches and bushes, grasses and ant hills, wandering and nesting, teach the next generation to find, a life to live while upon the Earth and then up into the sky to fly.

Should We Stay Or Should We Go Now? - Birds

And how do they know how?