276 Journal of Travel and Natural History 



ON MR WALLACES THEORY OF BLRDS' NESTS. 

 By the Duke of Argyll. 



THE "Theory of Birds' Nests," published in No. 2, Vol I. 

 1868, of this "Journal," by Mr A. Wallace, is a theory which 

 appears to me to be altogether unsound. It rests upon an 

 ingenious but a very partial and a very arbitrary selection among 

 the facts of nature ; it takes no account whatever of many of 

 those facts which are nevertheless conspicuous \ and it is supported 

 by arguments which are often inconsistent with each other. 



The theory itself is prefaced by some general observations to 

 which also I venture to take exception. I propose in this paper 

 to deal with the various propositions of Mr Wallace in the order 

 in which they occur, whether in the prefatory remarks, or in the 

 more formal exposition of the theory itself 



In the first place, then, Mr Wallace condemns " the very 

 general belief that every bird is enabled to build its nest by means 

 of some innate or mysterious impulse," and he opposes to this 

 belief, as the true doctrine, that birds are enabled to build their 

 nests "by the ordinary faculties of observation, memory, and 

 imitation." 



Now, as the young bird which (in England) is born in May or 

 June 1868 will proceed in April or May 1869 to build a nest as 

 perfect and as beautiful as that in which itself was hatched, I do 

 not see how either memory, or imitation, or observation can have 

 anything to do with its architectural powers. It is true, no doubt, 

 as Mr Wallace observes, that some birds (some only) shew con- 

 siderable intelligence in "modifying the position, form, and 

 material of their nests to suit the changed conditions with which 

 the presence of man surrounds them." But this margin of varia- 

 tion, like all the modifications of mere instinct, is confined within 

 narrow limits; and this degree of intelligence, whatever it may 

 amount to, is itself hereditary and innate, so that it is no greater 

 in an old bird which has seen many summers than in a young bird 

 which has not seen more than one, and never can have seen any 

 nest constructed. The innate character of the physical powers 

 and tendencies which lead to nest-building, is well seen in the 

 chick of the Telegallus, which begins scratching and scraping up 

 the ground the moment it quits the egg, in unconscious but 



