We live on 13 acres. Space isn't too much of an issue, I was thinking of the breeding pens would be in use only when we want babies so not put into use all the time. Right now I have them in the barn- they have the run of most of the main floor and we also built them a run outside that is 25 x 50- smaller than what they have inside but not too crowded when everyone is outside.
I am in the process of building the pens for the chickens and thus wanted to start thinking of the ducks. The smallest ducks we have are the mallards, we also have jumbo Pekins and WH and it looks like we ended up with a few standard sized pekins (they look like they are half of the bigger pekins).