I keep hearing how wonderful Black Oil Sunflower seeds are for my girls - as a treat and to supplement during the colder times. So I thought that I should include a few in my garden this year. But, I can't seem to find any sunflower plant seeds called 'black oil'. SO - (1) Are 'black oil' sunflower seeds from a particular flower? (2) Are all sunflower seeds 'black oil'? (3) And, should I try to find seed packets - or - just save a few from the bag fed to the girls? (4) AND where do I find them as feed?