Just joined as seems a good place to get bird info
In Eindhoven just now and on a local small lake (in town). With many ducks there were two identical that I have never seen before. They were.
They were normal "duck" size. Pure black (including grey ish beak, looked like normal black/brown eyes. (no binocs with me but they were only 6 feet away!!!)
No other colour I could see (birds stayed on water). With a small say 1 inch+ circular throat/ upper chest white mark
Any ideas. Checked out American black duck I would say no. There was no crest