106 NATURAL SELECTION v 



render it certain that the peculiar notes of birds are acquired 

 by imitation, as surely as a child learns English or French, 

 not by instinct, but by hearing the language spoken by its 

 parents. 



It is especially worthy of remark that, for young birds to 

 acquire a new song correctly, they must be taken out of 

 hearing of their parents very soon, for in the first three or 

 four days they have already acquired some knowledge of the 

 parent notes, which they will afterwards imitate. This shows 

 that very young birds can both hear and remember, and it 

 would be very extraordinary if, after they could see, they 

 could neither observe nor recollect, and could live for days 

 and weeks in a nest and know nothing of its materials and 

 the manner of its construction. During the time they are 

 learning to fly and return often to the nest, they must be able 

 to examine it inside and out in every detail, and as we have 

 seen that their daily search for food invariably leads them 

 among the materials of which it is constructed, and among 

 places similar to that in which it is placed, is it so very 

 wonderful that when they want one themselves they should 

 make one like it ? How else, in fact, should they make it ? 

 Would it not be much more remarkable if they went out of 

 their way to get materials quite different from those used in 

 the parent nest, if they arranged them in a way they had seen 

 no example of, and formed the whole structure differently 

 from that in which they themselves were reared, and which 

 we may fairly presume is that which their whole organisation 

 is best adapted to put together with celerity and ease ? It 

 has, however, been objected that observation, imitation, or 

 memory can have nothing to do with a bird's architectural 

 powers, because the young birds, which in England are born 

 in May or June, will proceed in the following April or May 

 to build a nest as perfect and as beautiful as that in which it 

 was hatched, although it could never have seen one built. 

 But surely the young birds before they left the nest had 

 ample opportunities of observing its form, its size, its position, 

 the materials of which it was constructed, and the manner in 

 which those materials were arranged. Memory would retain 

 these observations till the following spring, when the materials 

 would come in their way during their daily search for food, 



