I just wanted to add, that this an eclipse male Common Pochard. It has red eyes. At first I thought that this colours lokoked to exaggerated, but I think its because of light and camera settings. Many eclipse male CP look more similar to an adult winter male CP, but your bird is within variation.
Also bill is more uniformely dark than an 100% ID-book eclipse male CP, but the male pattern is still there. Assuming, this picture was taken recently?
If you look hard enough, you can imagine a slightly unusual head-bill shape for CP, but I think this is due to photographic angle producing foreshortening effects.
A question to more experienced people: if this bird was guardening chicks (which is the job for female CP), how can an intersex female CP be excluded from this picture?