Public land in Wisconsin.....any pheasant there is a planter. In truth, most any pheasant in Wisconsin is a planter. Even tho we tried importing true wild birds from nearby states and stocking them in various places, along with trying to raise true wild strains to release with the hopes of establishing a viable wild/native population, for the most part, Pheasant hunting in Wisconsin is basically a give and take proposition. That said, nuttin' wrong with the bird you shot. Considering the numbers of birds raised and released in the state, a few with color variations is quite normal. Could very well be a recessive gene showing itself or inbreeding due to the game farm environment. I raised pheasants myself for many years and saw birds that were almost pure white like a domestic chicken to those that were almost black. This using only standard Ringnecks as breeding stock. I also raised some of the "fancy" breeds of Pheasant that were completely different looking....some looked more like Peacocks or parrots than pheasants. Local game farm I work my dogs at regularly releases "chocolates" or "Black" pheasants along with the ringnecks and gives a prize to those that bag one and bring it back to the clubhouse.
....anyway, good shooting.