There are over 30 different species of birds that will nest in a birdhouse? These include many that frequent your back yard. Some of these types of birds are the house wren, chickadee, tufted titmice, nuthatches, bluebirds, purple martins, wood duck and screech owls. With a little research one can set up multiple birdhouses of different types to attract many of these birds. House wrens can fit into a birdhouse with a 1 1/8" hole, whereas chickadees, nuthatches, and titmice can fit into a birdhouse with a 1 1/4" hole (http://birdhouseaccents.etsy.com). The blue bird needs a 1 1/2" hole birdhouse, the purple martin a 2" entry hole, wood ducks and screech owls need a 3" to 4" oval entry hole.
With a little knowledge as to the dimensions of a birdhouse, how high to place one, what types of species enjoy what types of food and when the nesting season begins, one can make their yard a popular place for all types of birds.