112 NATURAL SELECTION v 
when fabricating their nest. They had no standard to work 
by, no nests of their own kind to copy, no older birds to give 
them any instruction, and the result is the abnormal structure 
I have just described. Perhaps these chaffinches imitated in 
some degree the nest of some New Zealand species; or it 
may be that the few resemblances to the typical nest of the 
Palearctic chaffinch are the results of memory—the dim 
remembrance of the nest in which they had been reared, but 
which had almost been effaced by novel surroundings and 
changed conditions of life. Any way we have here, at least, 
a most interesting and convincing proof that birds do not 
make their nests by blind instinct, but by imitating the nest 
in which they were reared, aided largely by rudimentary 
reason and by memory.” } 
This experiment also leaves much to be desired, but it 
undoubtedly shows that instinct alone does not determine 
the form and structure of a bird’s nest, or we should not see 
s0 great a departure from the type in the case of the New 
Zealand chaffinches. 
The Skill exhibited in Nest-building Exaggerated 
We are too apt to assume that because a nest appears to 
us delicately and artfully built, it therefore requires much 
special. knowledge and acquired skill (or their substitute, 
instinct) in the bird who builds it. We forget that it is 
formed twig by twig and fibre by fibre, rudely enough at first, 
but crevices and irregularities, which must seem huge gaps 
and chasms in the eyes of the little builders, are filled up by 
twigs and stalks pushed in by slender beak and active foot, 
and that the wool, feathers, or horsehair are laid thread by 
thread, so that the result seems a marvel of ingenuity to us, 
just as would the rudest Indian hut to a native of Brobdignag. 
Levaillant has given an account of the process of nest- 
building by a little African warbler, which sufficiently shows 
that a very beautiful structure may be produced with very 
little art. The foundation was laid of moss and flax inter- 
woven with grass and tufts of cotton, and presented a rude 
mass, five or six inches in diameter, and four inches thick. 
This was pressed and trampled down repeatedly, so as at last 
1 Nature, vol, xxxi. p. 683 (April 1885), 
