New to chickens so I am totally at a loss. I opened the tractor door earlier to let them free range for a little bit. I just went to check and all 5 are laying on the ground in a big pile. They seem to spread their wings and bring their feet up and scratch all over theirself and then rub their face on the ground. One is simply laying on her chest pecking at the ground in front of her. I called her name and she turned and looked at me and then just started rubbing her face on the ground too. What are they doing? Is something wrong?? What do I do?