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 com- 
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 
