Birdhouses provide shelter and nesting sites, and though different species have different housing requirements, you can find houses for everything from orioles to owls. Make sure houses are weather-resistant and well ventilated, and place them with the entrance hole facing away from prevailing winds. Clean out houses after each nesting season. Natural nesting sites are especially important to birds, particularly trees and shrubs that serve double duty as both homes and food sources. Dozens of landscape plants provide dense cover for nesting during the spring and summer, and many produce berries that provide food during the fall and winter.
Dead trees play an important role in attracting birds too because they're often loaded with insects.
Despite your best efforts, some birds will choose to nest wherever they please. Another great way to attract wildlife is to leave an area of your yard wild, whether it's a fence line or an isolated corner. Wild areas needn't be messy, but they shouldn't be manicured. Without a source of water, birds won't be as plentiful, no matter how much food or cover or how many nesting sites you provide. At first glance, bat houses may look like birdhouses, but the only way to get into them is at the bottom.