108 NATURAL SELECTION v 
being already an ‘old bird,’ will be competent to instruct its 
younger partner (not only in the futility of ‘ chaff,’ but) in the 
selection of a site for a nest and how to build it; then, how 
eggs are hatched and young birds reared. 
“Such, in brief, is my idea of how a bird on its first 
espousals may be taught the Whole Duty of the married 
state.” 
On this difficult point I have sought for information from 
some of our best field ornithologists, but without success, as it 
is in most cases impossible to distinguish old from young 
birds after the first year. J am informed, however, that the 
males of blackbirds, sparrows, and many other kinds fight 
furiously, and the conqueror of course has the choice of a 
mate. Dr. Spruce’s view is at least as probable as the 
contrary one (that young birds, as a rule, pair together), and 
it is to some extent supported by the celebrated American 
observer, Wilson, who strongly insists on the variety in the 
nests of birds of the same species, some being so much better 
finished than others; and he believes that the less perfect nests 
are built by the younger, the more perfect by the older, birds. 
Nearly a century ago the Swiss naturalist, Leroy, made a 
similar observation. He maintained that there is a distinctly 
perceptible inferiority in the nests built by young birds ; and 
he further remarks that the best constructed nests are made 
by birds whose young remain a long time in them, and thus 
have more opportunity of learning how they are made. He 
says that the nests of young birds are ill made and badly 
situated, and that these defects are remedied in time, when 
their builders have been instructed by a sense of the incon- 
veniences they have endured. He maintains that nests of the 
same species of bird differ as much as human dwellings, and 
that of a hundred swallows’ nests no two are exactly alike ; 
and he imputes to want of long-continued observation our 
failure to discover improvement in them. 
At all events, till the crucial experiment is made, and a 
pair of wild birds, raised from the egg without ever seeing a 
nest, are shown to be capable of making one exactly of the 
parental type, I do not think we are justified in calling in the 
1 The Intelligence and Perfectibility of Animals from a Philosophie Point 
of View. By Charles Georges Leroy. 
