They are quite attractive birds, looks like the light was to poor to show them at their best.
Thanks KenAmerican Wood duck
Is it a Carolina, its head should be a dark green.
Slimbridge (and the other WFT sites) are great for getting shots of captive birds aren't they.
Nice pic - hope you don't mind, but I would've preferred a lower angle seeing as it a wing-clipped bird in a collection and therefore more approachable.
Just a thought.