My first two hens were out 2 months old, and now they are about 7-8. Along the way we lost 2. My first two ladies are best buds and they dont tolerate anyone new. I just got 2 more, because we always wanted 4, but these new girls are about 3-4 months my guess. The older gals are mean and circle the new girls smaller cage constantly, and will immeditalely go after the new girls if given a chance. I dunno if it will get better, and I am thinking about trying the trick of taking out the older birds and reintroducing them later as the new birds, but I had one question; does that trick work on birds that are older and bigger than the "established" birds? How long do you keep the bad bird out? Another question I have is the point of removing the bird is to let her forget her home so you have to move her so she cant see the coop/run, right?