Pillar Glass Seed Feeder These Glass Bird Feeders feature a wide landing platform that will appeal to cardinals. Fill with safflower (carthamus) to considerably reduce the number of sparrows and free the feeder for use by the cardinals. Made of recycled glass, the feeder is dishwasher-safe. It is available in several colors, and matches the Hummingbird Bouquet glass bottles, both in shape and color.