IV
You must hear the nighthawk and the whip-poor-will. Both birds are to be heard at twilight, and the whip-poor-will far into the night. At the very break of dawn is also a good time to listen to them.
At dusk you will see (I have seen him from the city roofs in Boston) a bird about the size of a pigeon mounting up into the sky by short flights, crying peent, until far over your head the creature will suddenly turn and on half-closed wings dive headlong toward the earth, when, just before hitting the ground, upward he swoops, at the same instant making a weird booming sound, a kind of hollow groan with his wings, as the wind rushes through their large feathers. This diver through the dim ocean of air is the nighthawk. Let one of the birds dive close to your head on a lonely dusky road, and your hair will try to jump out from under your hat.
The whip-poor-will’s cry you all know. When you hear one this spring, go out into the twilight and watch for him. See him spring into the air, like a strange shadow, for flies; count his whip-poor-wills (he may call it more than a hundred times in as many seconds!). But hear a circle of the birds, if possible, calling through the darkness of a wood all around you!