Many birds have colors that we don't notice, like hummingbirds, till they catch the right light. Here is another example, the buffle head duck. Catch them just right and it looks like a different bird.
I know just what you mean Kildale. Even a starling shot from the right angle has many different colours in its plumage. So glad you photographed the duck in the way you did as it does appear, on first glance, to be two different birds.
