I Took this series of photos at East India Dock Basin on Monday afternoon; a flock of five Common Pochard, four drakes and a duck, have been frequenting the basin for a few days. All four drakes were courting the duck but she showed no interest, diving frequently to avoid their unwelcome attention. After about ten minutes the drakes had reached a state of high excitement; two of them relentlessly pursued the duck but the third chased the fourth, caught it and copulated with it, forcing it completely under water for at least a minute on one occasion. I feared the fourth drake would be drowned so I shouted and clapped my hands but drake three was completely oblivious; eventually drake four dived with drake three still hanging on and both birds disappeared beneath the water for over a minute before surfacing independently and going about their business as if nothing had happened. I have seen Mallards behave in this way but I have never seen Pochard (or any other aythya for that matter) do anything like this, it made for an interesting intermission in what was otherwise a fairly uneventful afternoon.