Did you know that "bird houses" are really Nesting Boxes? Many birds will nest in cavities so a nesting box is perfect to provide shelter for hatchlings. Nesting boxes should NOT have perches as predators will use them to get at the nest. They should also be hinged for yearly cleaning. Mounting them on a 4-6 foot green metal fence post is perfect. Bringing birds to your yard is also beneficial for your gardens as they will eat pesky garden insect pests. If you have open areas, you may want to place TWO boxes 15 feet apart. A tree swallow may take one box but will NOT let another tree swallow move in next door. But they WILL let a bluebird move in! If you have less open area, you are likely to see a wren move in. It's always fun to watch them build their nests and their families! Be patient!