Snags with old woodpecker holes provide homes for swallows, chickadees, nuthatches, bluebirds, owls, and other cavity_nesting birds that are rarely able to excavate their own nest sites. Snags provide ideal hunting perches for Red_tailed and Rough_legged Hawks, Bald Eagles, Hawk Owls, Great_horned Owls, and other raptors. Snags provide "songposts" to a wide variety of birds. Many small birds use songposts sticking above other vegetation to sing (to attract mates and proclaim nesting territory boundaries) and to perch on when looking out for predators and/or other birds.
Nesting Ledges. American Robins, Say's Phoebes, and Barn and Cliff Swallows will not use nest boxes, but they will next on platforms that are open on three sides. Platform nest ledges should be 6ν inches wide, 6ν inches long, and at least 8 inches high. Nest ledges can be easily fastened under the eaves of houses, buildings, bridges or on trees. They may be placed near a window where the behavior of birds using them can be easily observed. Place the nest ledge 8–16 feet above the ground.