CHAPTER n 



NESTING-HOUSES 



Adaptability of Birds. — Many birds have 

 adapted their nesting-habits, in part, at least, to 

 the changed conditions brought about through 

 man's agency, where the changes have not been 

 of too radical a nature. And some, indeed, seem 

 to prefer these new conditions to the original 

 ones ; chimney swifts have changed their nesting- 

 sites from caves and hollow trees to chimneys ; 

 the phcebe rather prefers the beams of a shed or 

 bridge to the cliffs, caves, and overhanging banks 

 which probably formed its original nesting-site ; 

 the eave swallow nests under eaves as well as on 

 cliffs; the barn swallow now nests almost en- 

 tirely in barns, in preference to cliffs and caves, 

 where it was once wont to nest ; the robin fre- 

 quently selects some portion of a building ; the 

 Carolina wren has been found nesting in a barn ; 

 several species quite commonly nest in artificial 

 houses provided for them. 



When the birds have shown such powers of 

 adaptability without much effort on man's part to 

 assist, there certainly is a large opportunity still 



