Snags provide ideal feeding sites for woodpeckers as many insects live and reproduce in decaying wood. Many snags are covered with small holes made by foraging woodpeckers. Though woodpeckers have powerful bills and neck muscles, they are only able to excavate nests in trees with soft decaying centers. Thus, dead or dying trees are preferred excavation sites. Unlike most other cavity_nesting birds, woodpeckers rarely use birdhouses. 22
Build a house for a specific bird. Build a birdhouse for a cavity_nesting bird that occurs in your region and lives in the habitat in which you plan to put in a birdhouse. (See Birdhouse Dimension Table to select a species.) Build the right size house and hole dimensions. Different species of birds require different sized houses and entrance holes. Inside dimensions must be large enough to accommodate the incubating biard and a brood of growing young. Entrance hole size is especially important. If the hole is too small, the bird you built the box for won't be able to get inside. If the hole is too big, predatory birds and mammals will be able to get inside and reach the nest, and cavity_nesting birds may not use the house.