NESTING-BOXES 241 



English sparrows', and two bluebirds'. Shortly after 

 this the eggs of the sparrows were removed and no 

 more eggs were laid, although a new nest was built. 

 On July 4, there were twenty swallows' nests, three 

 bluebirds', and one English sparrow's. So that as 

 a result of removing the sparrows' eggs the number 

 of native birds using the boxes was about doubled. 

 But the only final solution of the problem seems to 

 be to kill the sparrow either by shooting or by trap- 

 ping, as explained in Chapter XIV. 



The most essential points to consider in making 

 bird-boxes may be briefly summarized as follows: 

 (1) the size of the entrance hole, which should be 

 of the right size for the bird desired; (2) the lo- 

 cation of the box, which should be on posts in the 

 open rather than on trees in the shade; and (3) 

 the protection of the boxes from the birds' enemies, 

 especially, the cat, the English sparrow, and the 

 squirrels. Of secondary importance are the following 

 points; material of which made, size, shape, type, 

 height put out, and direction in which the entrance 

 hole faces. 



Open houses. There are some birds which do not 

 nest [in cavities, that will, however, build nests in 

 shelters having open sides. Birds which have been re- 

 ported as using these shelters are listed on page 227. 



For the catbird, song sparrow, and brown thrasher 

 the shelter should be open on all four sides and 

 placed in shrubbery where these birds nest. 



