 Black sunflower seeds are highly recommended for use in bird feeders because they attract a wide variety of birds, have a high ratio of meat to shell, and are high in fat content.Other common bird seeds include Niger, or thistle seed, a favorite of goldfinches, millet for sparrows and juncos, and safflower for cardinals, among others.Suet is recommended for insect-eating birds like nuthatches and woodpeckers.