I have 3 standard sized hens,2 standard 3 month old pullets, 2 bantam cochins, one silkie and 2 serama all in one large run, with 2 coops. I did have trouble in the begining from my Barred Rock hen. I isolated her for a few days and knocked her down the pecking order. Now all is well. Make sure you have lots of get away spots for them to run under or into, if need be, from any bullying. Keep a close eye for a few days... seperate with chicken wire for a few days, if possible, where they can be near each other, but not touch each other. My Serama cockerel is now courting several of the big girls, lol. Now that is funny!