Most of the domestic ducks that are farmed today are descended from the wild mallard (Anas platyrhynchos). Presumably the mallard was chosen for domestication because many of the wild population tolerate the close proximity of humans, unlike other ducks. Being of the same species enables domestic ducks and mallards to interbreed and produce progeny of varying colours. This pair exhibit the colours of wild mallard but permitted a quite close approach.
photo © T. Boughen Camera: Nikon P900