Birdhouse Types
As you are building your birdhouse, consider that different birdhouse dimensions attract different types of birds. Construction materials, ventilation, drainage, entrance hole, accessibility, and predator access will also influence how habitable a birdhouse is. Birds will choose houses they find comfortable and that will keep them safe from predators such as cats, raccoons, snakes, and other birds.
SOURCE: http://bountifulcitiesblog.blogspot.com/2009/02/birdhouse-specifications.html
