No. 4.] BIRD HOUSES AND NESTING BOXES. 199 



Nevertheless, there are a few rules that it is best to follow in 

 ' making and erecting bird houses to secure the best results : — 



1. Let the roof be made tight and overhang the entrance 

 enough to carry rain clear and keep the sun from shining in 

 on the young. 



2. Do not make the bottom of the box too tight. If any 

 rain drives in it should run out. 



3. If the box tips forward a little on the side of the entrance 

 hole when set in place it will shed rain well. It should never 

 lean backward. 



4. Provide a way of opening the box quickly unless you 

 intend to burn it and replace it after the first season, as is done 

 sometimes with gourds and shingle or bark boxes. 



5. Make the entrance hole and the box itself just large 

 enough for the bird you want — no larger. This will tend to 

 keep out larger birds, as well as the birds' enemies, will give the 

 bird a better chance to defend its home, and will save material. 



6. Make nesting boxes of weathered wood, or paint or stain 

 them with colored linseed oil of a neutral tint resembling dead 

 wood or bark, or put them up in the fall that they may be- 

 come weather-stained before spring. Apparently birds are less 

 suspicious of such boxes than those made of new, bright 

 lumber, but they have been known to use the newest of the new. 



7. Fix nesting boxes on buildings or on poles rather than on 

 trees, and make them inaccessible to cats, squirrels, mice and 

 rats. 



8. Where it seems best to put them in trees, choose isolated 

 trees which can be protected against cats, squirrels, weasels, etc. 



9. Ordinarily ventilation is unnecessary if the entrance is near 

 the top of the box as it should be, but in very hot summers 

 young birds are believed to have died of heat in unshaded boxes 

 mounted on poles. Ventilation may be provided by boring 4 half- 

 inch holes in the sides of the box near the top and filling them 

 with corks which may be removed in extremely hot weather. 



10. It is best to clean out the boxes each autumn, burning the 

 old nesting material to destroy dirt and vermin, and putting in 

 a little chaff as a foundation for a new nest. 



A few practical details in regard to carrying out some of the 

 above rules should be noted. 



