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Some species of birds are known as cavity dwellers, which means they only build their nests inside a cavity, usually a hollow inside the trunk of a tree. Manmade birdhouses (also called a nest box) provide a good simulation for a tree cavity, and have been credited for bringing the Eastern Bluebird back from the brink of extinction.

Dimensioning is an important aspect of preparing a nest box for a particular species. It is desirable for the hole to be just large enough for the desired species, but too small for a larger, more aggressive cavity dweller. Studies conducted several decades ago helped determine the inside box dimensions most acceptable to each species.

Use a carpenter’s square to lay out perfectly square corners. You’ll want the walls and floor of the house to fit together without gaps.

Like people, birds do not have any hard rules about what they will live in, but the closer a box size is to the preferred dimension, the more likely it will be to attract the desired species. Fir, pine, cedar, and plywood all make good nest box construction materials. Consider using scrap lumber or previously used wood as an environmentally sound means of recycling it.

A birdhouse should never be constructed with wood which has been chemically treated to protect it against rotting. A few one-half inch holes near the top of the box on each side will provide a means for the box to ventilate by natural convection. It is also a good idea to drill some small holes in the bottom corners to allow drainage of any water that gets inside.

The birdhouse should be placed in a naturally shaded location, such as on the north side of a tree truck. Consider using aluminum nails if you are nailing to the side of a tree. They will neither rust nor damage saw blades that may strike them later.

Every birdhouse should be constructed in such a way that it can easily be opened during the month of March for removal of old nesting material and the parasites that accompany it. Use gloves while handling this material, and beware of other critter that may be hiding inside: snakes, rodents, & squirrels. Having a hinged top with a hook lock is an easy solution.

A perch looks cute on a birdhouse, but contrary to popular belief birds do not need them. Cavity dwelling birds are equipped with very strong claws for hanging onto vertical surfaces.

Mounting a birdhouse on a tree immediately above a limb or installing a perch provides a platform for cats, raccoons, opossums, rats and non-cavity dwelling birds to destroy the nest. Crow and jays cannot easily hold onto the side of a box and would be more apt to leave it undisturbed.

If you decide to paint your new birdhouse, remember that different birds prefer different colors. Martins, for example, prefer white. Do some research on the species you are attempting to attract.

Don’t paint the inside of the house. Birds will not nest in houses which are painted inside or which smell like humans. Expect your new house to hang unoccupied for a few weeks before birds settle in.

Finish the bird house with two or three coats of external latex paint. Finish with three coats of polyurethane. New water-based polyurethane finishes have been developed which work well over paint and do not yellow the finish color. These new finishes are environmentally friendly, and clean up easily too.

Once you have constructed your basic birdhouse, you may hang it up and enjoy your handiwork. Or, if you are feeling adventurous and want to create a work of art, you may decide to get fancy. All you need is a pine board, some paint of different colors and some imagination. Be creative! This is your chance to add your personal touch to the birdhouse project.