How elaborate you make your bird house depends on your personal sense of aesthetics. For the most part, all the birds care about is their safety and the right dimensions: box height, depth and floor, diameter of entrance hole, and height of hole above the box floor. Refer to the following chart, keeping in mind that birds make their own choices, without regard for charts. So don’t be surprised when you find tenants you never expected in a house you intended for someone else.