I have ducks too, and chickens, although the ducks are quite quiet, the chickens are very noisy, we have found that if we give in to them, they stay noisy, if we ignore them like noisy children, they eventually quieten down, when they realise they wont get what they want.
Try a machine called "shotgun" preferebly a 12 cauge pumpaction. Put things called shells into the shotgun (read instructions) point the end with one or two holes at the ducks. The other end you put against your shoulder. Take your left hand under the barrel with the one or two holes and the other hand to the circel with a metalstick pointing down. Pull the trigger withthe finger closest to your thumb. Then pull the mechanism over your left hand and then repeat