BIRDS WITH UNMUSICAL VOICES. 



133 



strange whirr-r-r-r-rrr reaches our ears, sounding 

 perhaps like the very distant bellow of a cow for- 

 saken on some lonely hillside. The sound has a 

 sonorous quality which it is hard to describe. I 

 have heard a fractious rolling door 

 make just such a noise, and in a 

 sudden rise from the ground the 

 pigeon makes a weaker but simi- 

 lar one by the rapid beating of 

 the air with his wings.* Wil- 

 son says the same sound may 

 be produced by blowing strong- 

 ly into the bunghole of an 

 empty hogshead, but he adds 

 that the night hawk doubtlessly 

 makes this noise by the sud- 

 den expansion of his capacious 

 mouth while he passes through 

 the air ! (What an extraordinary theory !) I am 

 sure that the rapid beating of the bird's wings to re- 

 cover himself after his swift fall is the most satisfac- 

 tory explanation of the mysterious " whirr-r-r-r-rrr." f 



* I must not omit to say, too, that the partridge, at the end of 

 his " drumming," also whirrs. 



f This is Audubon's theory. But I do not entertain the slight- 

 est doubt about the matter. The sound reaches the ear just after 

 the recovery, and this is of itself an all-sufficient proof that the 

 wings produce it ; nevertheless it is said that the European goat- 



The Night Hawk's 

 tumble. 



