HOW THE BIRDS KNOW 313 



screams, and cries of prehistoric forms to the ex- 

 quisitely modulated notes of to-day, which should 

 go on increasing in number through notes learned 

 from each other and in timbre with the constant 

 use of the vocal chords. I am satisfied that our 

 birds of to-day sing truer to form, more surely mod- 

 ulated notes than the birds of the ancients; while 

 I can not conceive the delicacy, the molten sweet- 

 ness that ages to come will hear. There is no way 

 to estimate how long the birds have been singing; 

 when we recall that the oldest bit of translation 

 existing in the world is the lament that "the good 

 old times are gone forever," this seems a very old 

 world indeed. 



The birds have been building longer, in all 

 probability, than they have been singing. Here a 

 change can be better noted. In my personal ex- 

 perience, it appeals to me that the hummingbirds 

 and gnatcatchers build more nearly perfect nests. 

 I know that the vireos of my childhood went to 

 no such extent in decoration as that family goes 

 to-day. Vireo nests were compact, dainty, and 

 lovely, but I never saw them decorated with unique 

 seed-pods, snow-white festoons of cobweb and birch 

 tissue, and newspaper, as the nests reproduced in 

 this book. 



The oriole nest with a window is an arresting 

 thing. This nest could not have been built "in- 

 stinctively" since the bird possessed no inborn 

 instinct to guide her in its construction. It could 



