3-4 sqr foot for a chicken, 5-6 for a duck in the coop. Start then free ranging together if you can then they can be locked up together. The rooster should not be a huge problem if you have enough hens (I would have more than two for this, probably at least 5 hens) and vise versa for drakes (you really have to make sure your female:male ratios are perfect to combine) Consider the mud and all of the water that ducks need, chickens can get mud stuck and dried to their feet really easily and can drown in too deep of water, especially young birds. Everyone I know who combines them have no issues, they kind of keep themselves to themselves during the day outside and the chickens will perch high above the ducks in the coop at night. If you do this consider switching to flock raiser for all of the birds, but obviously oyster shell for the chickens, but as I don’t have ducks I would definitely talk to more people about feeding them all.
