I had a sick hen who I put in my garage for 1 week of quarantine to make sure the other girls didn't get sick. I just put Betty back with the other girls. My five hens have been together since they came in the mail at 3 days old. But now I have seen two hens peck at Betty and she is even bleeding a little. What do I do? Do I take her out again? How do I introduce them?
This is what is wrong with separating them. She is now at the bottom of the pecking order. There is not a simple solution. In the end, they have to sort it out. If you had been lucky, they would have pecked her but not drawn blood. In that case, you leave them alone to work it out. Problem is, once one is bleeding, there is a real danger they will peck at the blood even to the point of killing her. One thing you can do is get some BluKote and spray her wounds with it. This hides the blood and hopefully protects her while she heals. Another approach would be to take her back out then add her back at night while the others are asleep on the roost. Sometimes they wake up and act like they don't know there is someone new. Another is to have them out and pecking and scratching around, offer treats, then add her back, in the hope they will be so busy with treats they won't bother her. If there were only one doing the attacking, you simply remove and isolate the attacker, then put her back in about a week. Then the attacker becomes the one at the bottom of the pecking order.