They fly at night--the woodpeckers and orioles and cuckoos, and lots of others.

They're afraid, I guess, don't you?
But I've seen them.

I've watched them.

They tell each other when they're going to start." "Oh, David," remonstrated Mrs.Holly, again, her eyes reproving, but plainly enthralled.
"But they do tell each other," claimed the boy, with sparkling eyes.
"They must! For, all of a sudden, some night, you'll hear the signal, and then they'll begin to gather from all directions.

I've seen them.
Then, suddenly, they're all up and off to the South--not in one big flock, but broken up into little flocks, following one after another, with such a beautiful whir of wings.