Gud even FJer, With their different eating habits, can chickens and ducks be raised together? Not in a pen, but outside where there is a lot of space.
Not advisable. Ducks are carriers of many chicken diseases. Likewise you don't raise turkey and chickens together. You may try them in a small scale hobby farm, but not when you do commercial farming for profit. Even in a small scale, male ducks can harm chickens.