NESTS AND NEST-BUILDING IN BIRDS 175 



forever by both old and young the moment the latter become 

 independent, that is when its purpose has been served; the 

 main exceptions to this common procedure are to be noted only 

 in such species or individuals which use the site of the old nest for 

 that of a new, either in the same or successive seasons. In a few 

 cases the young repeatedly leave the nest and return to it again 

 for a brief season, as in some of the swallows and swifts, but 

 this seems altogether exceptional. The rather strong association 

 which the young of most altricious birds form with their nest 

 in the course of their brief stay within it is quickly broken by - 

 the still stronger influences which draw them away, whether it 

 be fear, hunger, or parental influence, for it is the young, always 

 the young, in which the commanding instincts of the adult are 

 centered, and about which their lives revolve,- — but only until 

 these instincts are satisfied. 



Protection through guarding or concealment is the essence of 

 nest-building, and we may be sure that all modern birds both 

 concealed and guarded their eggs, if they did not at one time 

 build proper nests. Certain it is that some of them like the 

 European cuckoo, falter or fail in this work at the present time 

 through the loss of an instinct which their ancestors displayed. 

 All possess the same tools, however much they may vary in 

 form, size, or strength, and failure to build nests at the present 

 day cannot be attributed to clumsy tools or to any structural 

 peculiarity, but simply to the lack of inclination or impulse; 

 in other words they have failed to develop the building instinct; 

 protection in all such cases has been acquired in other ways. 

 Says Wallace: "The clumsy hooked bills, short necks and feet 

 and heavy bodies of parrots, render them quite incapable of 

 building a nest," but behold the quaker parrot " turning the 

 trick," and as Pycraft points out, building a great denied nest 

 of sticks, with entrance at side. 



The actual nest structure is certainly in the long run well 

 adapted to the needs of the offspring, the parent, or to both; 

 it is a refinement merely of simpler and more primitive means of 

 obtaining protection. The character of both egg and nest repre- 

 sent but one or two of many variables, and while often import- 

 ant, one or both may become negligible quantities in securing 

 the protection needed. Thus, primitive birds undoubtedly 

 made or adapted natural holes, and laid white eggs like nearly 



