128 ANIMALS OF LAND AND SEA 



hawks, whip-poor-wills, most flycatchers, etc., have large 

 broad tails, and undoubtedly these assist them in turning 

 abruptly downward, upward or sideways. 



Most creatures when flying make more or less noise, and 

 many have special sounding organs connected with their wings. 

 The bats all make a low swishing sound which is only audible 

 for a short distance. The wings of most birds make a swishing 

 sound which varies from the droning hum of the humming- 

 birds to the loud dull rustling roar of the large vultures, swans, 

 geese and ducks. These sounds are merely the result of the 

 rapid passage of the wings through the air. In some ducks, 

 on that account commonly called ''whistlers," the wings make 

 a loud shrill whistling noise in flight which on a still day may 

 be heard for a very considerable distance; this is due to the 

 vibration set in motion by parts of certain of the wing feathers. 

 The passage of most pigeons and doves and of some other 

 rapid fliers through the air is also accompanied by a more or 

 less distinct whistling. In addition to this pigeons and doves 

 on rising suddenly from the ground usually make a clapping 

 or rattling noise with their wings; but if not startled they 

 often rise quietly. The flight of some birds, especially of the 

 owls, is strangely silent, apparently so as not to interfere with 

 the detection of the slight sounds made by the creatures they 

 are seeking, by which means they find them. 



The droning of beetles and the buzzing and humming of flies, 

 bees, wasps, mosquitos, etc., are known to everyone; some 

 insects, hke the large cockroaches in the tropics, fly with a 

 loud ratthng noise, and some, like certain butterflies and grass- 

 hoppers, when on the wing make chirping or clicking sounds 

 at will by means of a special mechanism connected with the 

 wings. 



The flight of the large slow flying moths, like our common 

 cecropia, polyphemus, promethea and luna, like that of the 

 owls, is almost noiseless; and it is fortunate for them that 

 this is so as otherwise they would soon disappear through 

 extermination by small owls and by the bats. 



