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. I 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. 1 



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 Philosophic Point 

 of View. By Charles Georges Leroy. 



