Pretty sure it isn't a black/mallard cross. The ones I've seen exhibit more black duck than mallard. And, I don't think there's any wigeon or pintail in there, either. The bill color on those crosses would be blue if anything. That said, I'm leaning towards a gadwall/mallard cross aka Brewer's duck. The bill has both colors (yellow mallard and black gadwall). The face, below the green, is similar to a gadwall and the wing markings also favor a gadwall.
Anyway you slice it, it's a cool looking bird.
I feel slightly sorry for a man who has never patterned his gun, who has no idea how far his chosen load will retain killing penetration. But I'm extremely sorry for the ducks he shoots at beyond the killing range of his gun and load - Bob Brister