Replace any platform or tray feeders with tube feeders that have feeder holes at the bottom. Grackles feed from feeders on which they can land and roost. Tube and upside-down feeders will attract small songbirds, finches, cardinals and chickadees, but grackles will be unable to eat from the feeders.
Saw wooden perches off of bird feeders. Many small birds are very acrobatic and do not require perches on which to feed from feeders. Grackles cannot perch on bird feeders without the assistance of a platform. If you have a bird feeder with metal perches, gently tap the poles with a hammer. This will usually loosen perches enough to allow them to be removed without damaging the bird feeder.
Attach bird feeder cages to tube feeders. Cages, which are usually made of a wire or metal mesh, can be purchased at bird-supply stores. The cages feature small spaces in the wire that allow small birds to feed easily. Larger birds like grackles cannot access the bird seed.
Fill bird feeders with safflower or njer bird seed. Njer seed attracts a variety of finches, including goldfinches, purple finches and house finches. Cardinals, woodpeckers, chickadees and ground-feeding doves enjoy safflower feed. Grackles will not eat these types of seeds.