Here in the U.S., the black seeds are known as "Oil" seeds since they are usually marketed for sunflower oil, while the striped ones mentioned are known as "confectionary" and are the ones that are sold to be eaten by humans (after soaking in brine).
We feed the black ones mixed 50-50 with hearts, only to cut down on the left over husks. The black shells clean up easil in the spring and I find a lot of them in mice nests, so they're recycled naturally for other uses...