I lost two of my three 2 month old chickenetts to a raccoon two weeks ago. Last week, we went to buy 2 laying hens in their stead, so they were much larger than the 3 month old pullet. My mistake was to try to introduce them too soon as the larger hens ganged up on the smaller one. Now, little Sabel is getting mean and pecking me. She was sweet-natured, but she has been traumatized by the raccoon incident and by the bullying hens. I am sure how to change that behavior, except to hold her more and give her lots of individual attention.
So now, since I have been raising chickens for 7 weeks, I am an old sage.
My advice, if you haven't already purchased other chickens, purchase ones around the same age, size, and breed as the chicks you are replacing to avoid the bullying. In fact, it might be better to get chickens that are a bit smaller than the one you have to avoid the problem. If you have two or three in your own flock, then you might want to introduce a single new chicken that is slightly larger than the chickens you have. I'm speaking from logic, not real experience here.
Someone recommended keeping a new chicken in a coop and pen for two weeks before releasing them to free range. My pen is very small and the chickens I got were use to a very large and spacious pen. They would pace and squawk loudly all day long. The younger chicken was already free roaming. On the second day, I decided to release one new chicken at sunrise with the younger chicken so that they would get use to foraging together and get some time out of that tiny pen. Midday, I would swap the older hens so the other older hen could roam with the younger one. My reasoning that the one new chicken will not stray too far her "flock-mate(?)" in the pen proved true. At night, I still keep the younger chicken in a cage by herself. After 5 days, I released all three hens to free roam at dawn and roost together at night. So far, the strategy has worked very well, and they also are getting along better.
