House sparrows and starlings may try to move in to your box. It is legal to remove or destroy the nests of these two bird species. There are many kinds of bluebird boxes. A simple nest box, like the one described in the instructions below, is beneficial and easy to make. Construction Mark and cut the pieces out of the lumber.
Larger holes attract starlings.
Attach the guard piece to the front piece with 2 nails and glue. Drill a small hole one inch from each short side of the back piece. Use these holes to attach your bluebird box to the post. Trim the corners of the floor piece diagonally. Use nails and carpenter's glue to assemble the box, leaving one side open.