NESTING-HOUSES 19 



difficult for the young birds to leave the house, 

 with the result that when they do leave they are 

 strong and better able to care for themselves than 

 they would be had they left the house earlier. 

 The combination of the three serves a twofold 

 purpose : it prevents the rain from beating in and 

 keeps the cats out. This is practically a cat-proof 

 house. From whichever position the cat may 

 attempt to reach the hole, whether from above 

 or below, the projecting roof renders it extremely 

 difficult for the animal to gain a position from 

 which it can reach into the nest. The difficulty of 

 reaching the house may be still further increased 

 by attaching the house to a long slender support. 

 The roof should be attached by hinges or in some 

 other method so that it may be easily lifted. On 

 the whole the author considers this the best type 

 of house for bluebirds and chickadees that he has 

 ever used. A projecting roof can be easily placed 

 on the hollow limbs previously described, and 

 the author also advises that a roof of this kind 

 be put on the bark houses, if any danger from 

 cats is anticipated. 



Observation Box, — An observation box con- 

 structed like that shown here allows a splendid 

 opportunity for studying intimately the home 

 life of the birds. One side is attached by a hinge 



