238 A THEORY OF BIRDS' NESTS. 



exposed to view, no matter whether there is the most 

 beautifully formed nest, or none at all. Kingfishers, 

 which build almost invariably in holes in banks ; 

 Woodpeckers and Parrots, which build in hollow trees ; 

 the Icteridaa of America, which all make beautiful 

 covered and suspended nests ; and our own Wren, 

 which builds a domed nest, are examples of the former ; 

 while our Thrushes, Warblers, and Finches, as well 

 as the Crowshrikes, Chatterers, and Tanagers of the 

 tropics, together with all Raptorial birds and Pigeons, 

 and a vast number of others in every part of the 

 world, all adopt the latter mode of building. 



It will be seen that this division of birds according to 

 their nidification, bears little relation to the character 

 of the nest itself. It is a functional not a structural 

 classification. The most rude and the most perfect 

 specimens of bird-architecture are to be found in both 

 sections. It has, however, a certain relation to natural 

 affinities, for large groups of birds, undoubtedly allied, 

 fall into one or the other division exclusively. The 

 species of a genus or of a family are rarely divided 

 between the two primary classes, although they are 

 frequently divided between the two very distinct modes 

 of nidification that exist in the first of them. 



All the Scansorial or climbing, and most of the 

 Eissirostral or wide-gaped birds, for example, build 

 concealed nests; and, in the latter group, the two 

 families which build open nests, the Swifts and the 

 Goat-suckers, are undoubtedly very widely separated 

 from the other families with which they are asso- 



