212 SOME COMMON LAND-BIRDS. 



Once I saw a new shape of nest in a peculiar situation. 

 In two or three colonies I have seen the same, but the location 

 for it is so unusual that I can only regard it as a Mew departure 

 in swallow architecture. The site chosen in these cases was 

 just above the window frame of clapboarded buildings. The 

 only support was a finish about an inch wide around the win- 

 dow and what little additional support came from the outward 

 slant of the clapboards. Two objects evidently must be held 

 in view, sufficiently large attachment surface to make the 

 nest secure, and protection from the weather. The first was 

 gained by making the nest nearly round and perhaps five 

 inches in diameter, which gave it a wide circle for its point 

 of support. The last was provided for by making it entirely 

 covered, the entrance being by a small round hole near the 

 centre. The nests looked like big mud pies, with holes in them, 

 stuck against the sides of the houses. These colonies were 

 small, but all nested in the same way. Sometimes these hemi- 

 spherical nests were not attached to the side of the building, 

 but were placed upon one another till they formed a great, 

 shapeless mass of mud, full of holes ; for even in this swallow 

 apartment-house, every nest still had its own private entrance. 



In the colony near my home I see scarcely two nests alike. 

 Each one is fitted to its own place, or to its maker's whim, but 

 there is a reason in it. Allowing for individual preferences, we 

 find that they fall into certain well-marked types. There are 

 the pocket nests, lying entirely under the eaves, the bottle-nosed 

 nests placed near the edge of the eaves where the exposure is 

 greater, and the hemispherical nests fully exposed on the face 

 of a vertical surface. 



It has taken not more than fifty years for the birds to learn 

 all this, and they still are learning. Men never began to learn 

 so much about building houses in so short a time. 



