Sounds like it probably was wounded, or just very, very stupid. Sure it was a merganser? When the coot start to come around here, you can do just about anything and they won't even look your way, butI doubt you mistook a coot for a merganser. If I had enough evidence to make me think it was wounded I probably would have shot it I guess ...Don't know that much about them. Don't think we have many up here, and I've never seen one that I know of.