In addition wings are used in at least three different ways in feeding. The red-tailed hawk may spread its wings as it sits on its prey, perhaps a behavior adapted to help the bird maintain its balance when dealing with struggling prey, perhaps to help smother the struggles of its prey.
The secretary bird of Africa is said to feed on snakes, poisonous and non-poisonous ones, and is said to use its huge wings as shields for its body in attacking them.
But the strangest use of wings in feeding is that practiced by a blackish African heron. In feeding in shallow water it takes a few rapid steps, apparently to bring it within reach of fish it has sighted, then spreads its wings, bringing them forward until they meet, and with the tips of the quills in the water. The head is in the canopy formed by the wings, and apparently it is here under this canopy that the fish on which it feeds are caught. The suggestion as to the correlation that presents itself is that the dark canopy thrown over the fish confuses them and makes them easier to catch.
INSTRUMENTAL MUSIC OF BIRDS
Vocal music bulks large in our avian springtime chorus, but don't overlook the instrumental music that accompanies it. The drumming of the downy woodpecker on the dead limb of a maple near my bedroom window is as much a part of my spring as is the cheery cheerup of our robin. It's not that woodpeckers are voiceless that they drum. The flicker can be called in with his particularly rich repertoire to repudiate it vociferously. All day the downy woodpecker goes about pounding his head against tree trunks, with his bill chiseling out wood-boring insects to eat. What more natural when springtime comes and he wants to tell the world, and especially other woodpeckers about it, to select a dead limb with a nice tone in my maple tree and hammer out a rolling tattoo—his love song and his challenge.
A DRUMMER The gray-brown ruffed grouse of a wood lot we used to have in the Chicago area is a drummer I miss. "Thump-thump ..." he started slowly, and then quickened to a roll that filled the forest with hollow sound and you wondered whence it came, unless you happened to know, as I did, that an old log in the patch of gray birch was the old cock's favorite performing stand. There he came to roll out his invitation to the demure hen grouse. A drummer, I've called him, yet he has no drum. It's his wings, striking the air, that thump and build up into a roll, its volume testifying to his great breast muscles as well as does the whir of wings as he hurtles away through the air when I come too close.
The snipe of a nearby marsh makes music with feathers and wind, music that is more enthralling to me than the song of the yellowthroat or the vocal imitation of stake driving by the bittern. Circling high, then with a change of pace, his "winnowing" or "bleating" spring song comes drifting down. There is still room for argument, but probably it's air rushing past the outer tail feathers that makes the sound. One year a short-eared owl nested in the nearby meadow. Owls generally are vocalists, even if we don't rate very high their hoots or yelps, but the short-eared owl also has an instrumental performance. Sometimes, when giving his mating song on the wing, a series of "toots," he interrupted this by a dive in which he brought his wings together under his body, with a clapping sound. It's part of the performance, but not, as might be said, the owl applauding his own show.
Over our public school each evening in early summer a nighthawk booms. He has a voice, and he uses it, calling "beep" as he circles high. But the climax of his performance is instrumental, wind on feathers. He heads down, wings high, toward the flat gravel roof on which his mate is sitting. As he approaches the roof he moves his wings down; the air rushing past the quills gives a tearing boom as he comes out of the dive and mounts skyward again.
At dusk, at a damp corner of our old wood lot, in the spring, I listened for the woodcock's flight song, a twittering of wing music as he circles up, and sweet music, too, for a wild fowler's ears, is the whistling of the wings of a passing pair of black ducks on their way in the early darkness.