I added my Calls right in after 24 hours of being separated in a look but not touch situation. They were fully feathered and full grown. I did have one of the ones I kept get a prolapsed penis, I read where if they are with bigger females they will extend it out so far to reach the bigger hens that this can happen. I took care of the situation myself and he is just fine. I had to amputate the end of his penis, about an inch of it. Some articles say he will still be able to mate and others say he will not. Spring will tell for sure. I have two Mallards that are not huge and they seem to like them the best. Mine are just fine altogether and now I have a new Drake that I got as a baby but they get along fine with him. He is young so spring will tell if he bothers them. My other drakes I had never bothered them before I rehomed them. I love my little Calls. I know a man that gets them and if he gets any females I might bring a couple of them home in the spring if anything happens to my older girls this winter. They are almost 8 now so I don't know how much longer I will have them. Sorry this is long, I love talking Ducks!!! Can you tell??? LOL@Luv Ducks Yes, I agree. I have 10 regular sized females right now. If I ordered two calls what are your thoughts on adding them? I am concerned about size and also if I get two males, will that really upset the apple cart with my all-females flock.