100 THE HUMAN SIDE OF BIRDS 



this sounding-box in their throats. In the latter 

 case, however, unlike the former group, the extra 

 coUs of the wind-pipe are stored near the skin of 

 the breast, and with no protective layer of breast 

 muscles as one might be led to expect. 



The emu in both sexes has a wind-pipe equipped 

 with an air pouch which makes it possible to give 

 forth a rolling sound like a very large dmm. 

 There is a hole in the outer wall of the wind-pipe 

 which allows the inner wall to protrude when filled 

 with air, forming itself into a sac for resonance, 

 which somehow enables the bird to make its drum- 

 ming sound. The ostrich roars so much like a lion 

 that even the Hottentots are often deceived by it. 



The drumming sound is more or less common 

 among the denizens of the wild wood. The wood- 

 peckers peck tattoos in many keys upon the 

 branches, and if the tree is dead, the sound is not 

 unlike a small kettle-drum. The rufiled grouse, 

 and others among the pheasant family, are drum- 

 mers of great skill. Indeed they employ this 

 means for signalling at a distance just as soldiers 

 have done for a long time. One is led to wonder- 

 ing if man did not get the use of the drum from ob- 

 serving the sound among birds. These feathered 

 drummers make the noise by striking their wings 

 against their bodies in such a way as to catch a 



