Black Oil Sunflower Seed-by far the most desired seed by birds. Attracts cardinals, chickadees, nuthatches, finches of all types, and grosbeaks. The high oil content makes it popular with birds and provides the heat and energy needed to live. Black oil sunflower has more oil content than any other! Black Oil Sunflower has a softer shell than striped sunflower, allowing smaller birds to open the shells more easily.