Ducks need to be in a flock, or at least a pair. It is not fair to get just one. I personally would not put calls in the same pen with standard sized ducks, there is such a size difference the calls could get hurt. If you want to keep it as a house pet, you can get a pair or trio and they will still be tame with handling. BTW, have you had ducks before? Ducks are super messy, their food flies everywhere when they eat, and they of course will climb into their water and splash that big time. I would personally NEVER keep an adult duck in the house, ducklings are messy enough. They would have to be fed and watered in something water proof like a big rubbermaid tub or your flooring will be ruined.