NESTS OF BIRDS. 535 



which they construct are destined much more for the recep- 

 tion of their eggs, and for the protection of the young, than 

 for their own residence ; for there are few Birds which pass 

 much time in their nests, except at night, and during the 

 period of incubation. It is impossible to watch the process 

 of their construction, without admiring the perseverance with 

 which the materials are brought together that are destined for 

 their erection, and the art with which these are arranged. The 

 form and structure of the habitations are always nearly the 

 same among the individuals of the same species ; but there 

 is necessarily a certain latitude in regard to the materials of 

 which they are composed, since the same could not be every- 

 where procured. The nests of different species vary greatly, 

 however, both as to form, structure, and materials; and these 

 are admirably adapted to the particular circumstances in which 

 the young families are respectively destined to live. Some- 

 times these habitations are constructed of earth, the particles 

 of which are united by the viscid saliva of the Bird into a 

 tenacious mortar ; and they are then commonly built against 

 the sides of a rock or wall. But, in general, they are corn- 



Fig. 277. NEST OF GOLDFINCH. 



posed of sticks, straws, and other vegetable substances ; and 

 are placed either on the ground, or among the branches of 



