Also know as the Rahja Shelduck. Pretty drab colours and it's not the cleanest bird I've seen for a while but I like that the head is in focus, wished the wings where also.
1DX - 800L f/5.6 - ISO200 - f/5.6 - 1/1250 - Hand Held - RAW and sharpening through ARC then some light finer sharpening with Smart Sharpen - 50% crop then resized.
ARC custom Preset - Contrast +2 Highlights -25 Shadows - +25 Whites +25 Blacks -25 Clarity +5 Vibrance +5 Saturation +5 adjust all to suit.
Richard