CONCEALED OR COVERED NESTS 133 



method of reproduction that a probably long and 

 continuous natural selection has evolved. Judged 

 by analogy there is not a single species of hole- 

 breeding bird (we more particularly allude to those 

 species that make no preparation by way of nest) 

 that we could feel justified in describing as not fully 

 equipped for producing a more complicated type of 

 architecture if such were necessary. Not only so, 

 but the very fact that we often find a more or less 

 elaborate nest constructed in these holes and crevices 

 seems conclusively to prove that birds have adopted 

 such methods for some special reason, and which is 

 still further confirmed by the fact that in many of 

 such cases we find nearly allied birds making similar or 

 equally elaborate nests in open situations. In many 

 of these instances of covered or concealed nests the 

 nest-building habit might almost be regarded as in a 

 transitional state at the present time, and in such 

 cases the coloured eggs are an additional confirmation 

 of the fact. Who, for instance, could doubt that the 

 Puffin or the Chough once occupied open sites for 

 nest-building when examining the faintly-marked eggs 

 of these birds ; or, on the other hand, fail to see in 

 the white and shining eggs of the Woodpecker and 

 the Kingfisher a certain sign of the long-continued 

 endurance of the present methods of reproduction ? 

 We are confronted with precisely similar phenomena 

 when we come to deal with domed nests, but we must 

 reserve their consideration for a later chapter. Inci- 



