I throw them Purina Kit-n-Kaboodles dry cat food from time to time, along with BOSS.
ETA: Info below:
Striped Sunflower Seed
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.
The birds have competition, however us! Striped sunflower seeds are the seeds the snack industry cultivate and roast that you see on the shelves of supermarkets and convenience stores everywhere. They are nutritional for the birds and us, containing protein, carbohydrates, fat and have a high oil content. In addition, they contain calcium, magnesium, zinc and Vitamin E.
Due to the popularity of striped sunflower seeds as snacks for humans, the crops are screened so that the largest seeds ultimately wind up in our pantries instead of bird feeders. The upside of this screening process is that the smaller striped sunflower seeds that are left over and sold as wild bird food are the smallest seeds from the entire harvest, making them even easier for more species of birds to be able to enjoy.
Striped sunflower seeds are a wonderful way to distract larger birds like grackles away from bird feeders so that smaller birds have a better chance of eating with less competition, especially when they are offered on an open platform feeder. As an added bonus, they make an inexpensive treat to offer squirrels so that you can attract them away from feeders as well.
Yes, the shells are larger than the shells of black oil sunflower seeds and have to be cleaned up in the same way, but the meat-to-shell ratio is not as different as you might think. The weight of the shells in a bag of black oil sunflower seeds is approximately 35-45%; the weight of striped sunflower seed shells is approximately 40-50%, a difference of only 5-15%. When you consider the benefits of feeding striped sunflower seeds to both larger species of birds and to squirrels less money, more distraction and less competition at bird feeders that small percentage of difference seems well worth its weight in gold.