Hello Benji,
I came back to your picture several times now, and I am still puzzled. I cant match the (appearant) wingtip and the twisted=wrongly positioned tail (???) to any species with confidence.
It seems a smaller bird to me (yes, I was many times wrong on that. And thanks Butty once more!), so I considered a Dipper first.
If this isnt the right answer, I would vote for a Goldeneye.
But I am confident these arent the right answers. As is another Duck, which I considered and will post the name in my next comment.