I have no issue with the green rocks, in fact the oof area of the photo is pretty spot on for me. There is good separation from the background, but you have retained a reasonable amount of context - the branch(?) and more water as well as the green rocks frame the birds for me ... And I do like a moorhen... When I used to live next to the canal they used to make me chuckle!
I suspect the green rocks feeling distracting is more related to the framing, which although good, I think is a little tight to the top wing. I think if the framing included a little bit more on top, a smidge more down the right and a little more down the left the breathing room around the birds would help. That said the tightness does add to the feeling of excitement in the moment ...
Its an impressive image, if not perfect, it's a fine achievement!