2i 4 THE STORY OF THE BIRDS 



heeven on the hairmony " ! From a popular 

 point of view, song is very loosely associated 

 with birds in general. All the smaller birds 

 are very generally believed to sing in some 

 way. The capacity for song, however, is com- 

 paratively a local one, practically confined to 

 the Passeriformes, which, as we have already 

 seen, are provided with a special apparatus for 

 producing it (conf. p. 49). But even amongst 

 the Passeres song is by no means a general 

 accomplishment, and is practically confined not 

 only to the smaller species of the group, but 

 most developed in the duller-plumaged species. 

 The music of birds, there can be little doubt, 

 is one of the many forms in which natural 

 beauty is expressed. But Nature is by no 

 means lavish of her gifts, for few birds com- 

 bine any marked vocal powers with brilliancy 

 of plumage. These birds display their beauty 

 in another way, by exhibiting it upon their 

 painted wings, or plumes, or crests, and so 

 fprth. Another striking feature of bird music 

 is its almost endless variety. If, however, we 

 class music as a secondary sexual character, we 

 need not feel surprised at its diversity, for of 

 all characters, secondary sexual characters are 

 the most variable, and modified in almost 



