I have a mother hen and 7 chicks. The chicks are now over 3 weeks old. Their mother is pulling feathers out of each chicks rear end.. where the tail joins the body. All of them have a bald patch now in that area, and some have sores and wounds and some blood. She only started doing this yesterday. I have never had a hen do this before... and she has raised many broods with no problems. I thought it was because she was stressed in the main run (although they have a huge area and its not overcrowded. So I let them all out to free range today... but she is still doing it, even when I throw some treats on the ground.. she prefers to pluck feather out of her chicks. The chicks keep going back to her when she calls them over for food.. and then she pecks them. Should I take her away from the chicks and leave them in a group with the main flock? They don't get picked on by other birds. And they are at the stage when they fly / scrabble up to the roosts for the night. Any ideas what the best thing to do is? And also what would cause this behaviour?