I have done some research on spotteds and since blue heads throw off 1/4 silver, 1/4 green heads, and 1/2 blue heads, the gene for color must be a codominant gene. Greenheads must be GG and silver heads must be SS and thus breed true to their own color. But a cross of greenhead and silver head would result in a hybrid trait GS which shows up as a bluehead. I also read that they were probably bred from mallards, pintails and possibly an australian breed. One of my female (from a greenhead x silverhead)offspring turned out snow white. Was this a mutation or a gene that is usually masked? Are their any other colors that show up from time to time? Unfortunately, she was killed by a coon when she was about 4 months.