Hi! I have 2 Pekin ducklings that will be housed in a coop (in about 4 weeks) with their 9 chick brooder box mates. I know how much square footage to allow in a coop for healthy chickens, but how much square footage per duck is needed in the coop? They will all have access to a netting- covered 10'x10' dog run and free range when I'm outside with them. Thanks!