Striped sunflower seed, sometimes called "stripers," are larger than black oil sunflower seeds and have a thicker shell. Their larger size and thicker shell make them harder to eat for small birds, but larger birds like cardinals, jays, woodpeckers, and grosbeaks have no problem breaking through to the delectable nutmeat inside. And although most people would consider chickadees, titmice, and nuthatches to be "small" birds, they also can easily open the shells of striped sunflower seeds.