I have 3 hens who are about 10 months old. About 3 months ago I added 2 chicks and once the pecking order was set they all get along fine. Problem is the 2 newer chicks won't go into the coop at night with the older chickens. The older ones don't like them being in their coop at night and push them around. If I go out and put them in the coop myself they stay put and all is well. I tried putting a light in the coop but that didn't work. I have a feeling it's more because the older hens are intimidating the younger ones. How do I get all the chickens to go into their coop together at night on their own?