t 
THE PHILOSOPHY OF BIRDS’ NESTS, 229 
But perfection of structure and adaptation to pur- 
pose, are not universal characteristics of birds’ nests, 
since there are decided imperfections in the nesting of 
many birds which are quite compatible with our pre- 
sent theory, but are hardly so with that of instinct, 
which is supposed to be infallible. The Passenger 
pigeon of America often crowds the branches with 
its nests till they break, and the ground is strewn 
with shattered nests, eggs, and young birds. Rooks’ 
nests are often so imperfect that during high winds 
the eggs fall out; but the Window-Swallow is the 
most unfortunate in this respect, for White, of Sel- 
borne, informs us that he has seen them build, year 
after year, in places where their nests are liable to be 
washed away by a heavy rain and their young ones 
destroyed. 
Conclusion: 
A fair consideration of all these facts will, I think, 
fully support the statement with which I commenced, 
and shew, that the mental faculties exhibited by birds 
in the construction of their nests, are the same in 
kind as those manifested by mankind in the formation 
of their dwellings. These are, essentially, imitation, 
and a slow and partial adaptation to new conditions. 
To compare the work of birds with the highest mani- 
festations of human art and science, is totally beside 
the question. Ido not maintain that birds are gifted 
with reasoning faculties at all approaching in variety 
and extent to those of man. I simply hold that the 
