NESTS AND NEST-BUILDING IN BIRDS 163 



life, — not to speak of the assumption that such nesthngs have 

 concepts of artificial, as distinguished from natural objects, 

 or that they have abstract ideas at all, — is no more fanciful 

 than that birds build on the copy-book plan, or under the tute- 

 lege of older and more experienced mates.'' 



The story of the mud dauber wasp which builds a unique 

 tube of clay for its eggs, and stores it with food for young which 

 it never sees, or of the spider's web and egg-cocoon, so faithful 

 to " copy " which is never used, of the caterpillar which weaves 

 a chrysaHs case but once in its life yet does it to perfection, 

 not to speak of similar illustrations by the hundred, — is not 

 needed to refute any theory of nest building based upon imita- 

 tion, memory, or intelligence of whatever degree. The proof 

 of instinct in the nest-building activities of birds lies in the 

 stereotyped behavior of the builders at work, as well as in the 

 stereotyped character of the nests of the different species, when 

 these are viewed in a proper light ; it is seen also in the relation 

 of nest-building to other phases of the reproductive cycle, as 

 well as in the correlated activities of adult and young. No 

 one for a moment could attribute mental powers below the 

 lowest plane of association to the nestlings of passerine birds 

 representative of the highest existing order, who had watched 

 their behavior or tested their capacities. On the score of beha- 

 vior alone the evidence is now conclusive that birds do not 

 build their nests from imitation or experience: they require no 

 visible standard, plan, or copy; they need no experienced mate 

 or tutor, but like Santa Claus, they "go straight to work," 

 and finish their task, without hesitation and commonly alone, 

 whether it be in the gloom of a cavern or chimney, the glare of 

 the tropical sun, or the bustle of a city street. Instinct alone 

 furnishes the building impulse, and in spite of many fluctuations, 

 whether due to experience, disturbance, or to any influence of 

 the environment whatsoever, it holds the builders wonderfully 

 true to their ancestral types. 



In the second paper referred to, 'Mv. Wallace endeavored to 

 show that the nesting habits of birds were largely responsible 



* Craig has shown that inexperience in pigeons is no bar to successful mating, 

 nest-building, and care of the young, only, as he says " their efforts lack some- 

 thing of the precision and the promptness which signally characterize the work 

 of experienced birds." Craig, Wallace: The voices of pigeons regarded as a 

 means of social control. American Journal of Sociology, vol. xiv, 1908. 



