AIDS TO NESTING 217 



bird will be shut out. Now nail these boards together to 

 form a tunnel about five inches square inside. Then 

 nail a piece, of board flat on the end farthest from the 

 entrance-hole to form the bottom, boring a small hole in this 

 bottom to let out water that might beat in. Have the 

 roof board a little wider than the box and set it either level 

 or sloping slightly forward. It should project a couple of 

 inches over the front, helping thus to shield the entrance 

 from storms. It should be screwed down, or else, if desired, 

 put on with hinges, so that access may be .had to throw out 

 English sparrows' nests and clean it out in the fall. No 

 perch should be placed in front, which would give only an 

 easy lodgement for sparrows, and is not needed by the birds. 

 Either nail to the back of the box a longer board to fasten 

 to the tree, or, better, make the back board longer, and nail 

 through the projecting ends. It can be painted outside, if 

 desired, or left in the natural wood. In the latter case it is 

 well to use weatherbeaten boards or else stain it. The in- 

 side of the boards should not have been planed, so that 

 young birds can better climb out when the time comes. 

 This model will be suitable for the majority of hole-nesting 

 birds, varied only according to the size of the desired oc- 

 cupant. 



Other Models. There are, however, other models pre- 

 ferred by certain species, as well as other devices acceptable 

 to the generality of birds. These will be briefly suggested. 



Tin Cans. After all, an old tin can with a small hole cut 

 at one end will suit a pair of house wrens as well as any 

 elaborate box. Bluebirds also sometimes occupy such re- 

 ceptacles, a tomato can being large enough for them. Since 

 metal gets very hot in the sun and might suffocate young 

 birds thus exposed, such nesting-sites should be placed 

 where there will be shade when the foliage grows out. 



