,56 THE LIFE OF A BIRD. 



formed of delicate grey lichens, and other vegetable 

 substances, and also of the skins of black cater- 

 pillars ! The interior is lined with the finest fibres 

 of dried vines. The following instance, narrated 

 by Audubon, pleasantly exhibits the principle of 

 selection which influences birds in proportion as 

 their nest progresses towards completion. 



The architects (warbling fly-catcher) began 

 their work by selecting some slender blades of 

 grass, which they attached to the knots in the 

 branch and to the bark. This formed the scaffold- 

 ing. They then collected bits of hornet's nests 

 and particles of corn-husks, which were pushed 

 into the interstices of the framework of grass, and 

 secured by silken ties. Slender grass blades were 

 now procured and laid within the frame. After 

 forming a sufficient bed of this material the in- 

 nermost lining was to be prepared ; and now 

 wool and horse-hair were alone employed. After 

 eight days of toil they had completed their nest ; 

 and a very warm and pretty structure it now 

 appeared, becoming in due time the home of a 

 happy and thriving family of young ones.* 



The American swift, in its method of procuring 

 * Ornithological Biography. 



