I also have one with a droopy wing and would love to know what causes this. Mine is a young Muscovy drake (we think it's a boy due to size) and he always lets one wing hang down while the other is tucked up in the normal position. It does not look like angel wing because the wrist bones are not twisted so the wing does not stick outward, it is just that he kind of lets that one wing hang down towards the ground all the time. He also has kind of of a humped back.
We figured he must just be mildly deformed in some way as the rest of the ducks are all fine and they are all on the same diet and live in the same conditions.
We figured he must just be mildly deformed in some way as the rest of the ducks are all fine and they are all on the same diet and live in the same conditions.