Birds need a safe place where they can hide from predators and seek protection from harsh weather. They also need places to perch, settle in for the night, and raise their young. You can help meet all these needs by including a mix of both evergreen and deciduous trees and shrubs. Many of these plants also double the avian appeal by providing seeds, fruits, nuts, and nectar.
Conifers, such as spruces, firs, and pines, as well as evergreen trees and shrubs like holly and some cotoneasters, provide year-round shelter for birds. Elderberries, maples, and other deciduous plants offer seasonal shelter and summer nesting sites. Combinations of both deciduous and evergreen plants form the framework of successful bird gardens because together they create a four-season safety zone, habitat site, and food source, especially when arranged as a windbreak or natural hedgerow.
Adding nest boxes to your garden provides a housing opportunity to songbirds that nest in cavities rather than on the ground or in the branches of shrubs and trees. Which species will inhabit the box depends on where you live, the surrounding habitat, and the construction and placement of the nest box.
"When setting out new nest boxes, consider the preferred habitat for different species, as well as the size of the entrance hole, and its distance above the ground," notes Stephen W. Kress, Ph.D., vice president for bird conservation for the National Audubon Society and author of the Audubon Society Guide to Attracting Birds.
Generally, a nest box with an entrance hole diameter between 1¼ and 1½ inches, and placed 8 to 12 feet above the ground, will suffice for most cavity-nesting backyard bird species while preventing starlings (an aggressive, nonnative species) from moving in. The best location for most any nest box is in an area protected from direct sun with the entrance hole facing away from prevailing winds.