CONSTRUCTION OF BIRD HOUSES.
Bird houses may be divided into three main classes: (1) those made of sawed lumber to specified dimensions; (2) the rustic type made of (a) slabs of wood with the bark left on, or (b) pieces of tree trunk, or (c) of sawed lumber trimmed with bark or twigs; and (3) cement or stucco houses. In each case the entrance should slant slightly upward to keep the rain out.
FIG. 10. WREN HOUSES.
Almost any sort of lumber may be used, but birds take most readily to that which has been weathered out of doors. A kind should be used which does not warp or check badly; white pine and cypress meet these requirements and are worked with ease. Yellow poplar is used and cedar with or without the bark left on has its friends for houses of the first or second classes.
Nesting boxes of sawed lumber should be painted on the outside to improve their appearance and to preserve them against the effect of the weather. It is often wise to leave a small amount of unpainted surface around the entrance, and all paint should be thoroughly dry before houses are expected to be occupied. Colors selected will depend somewhat upon the neighborhood, but white, grey, dull greens or browns are often used.