I let the chickens out and I notice Marcie has something on her butt. I looks like dirt has dried onto her feathers. I attached a picture of poop and it appears green. I shook her bottom a little bit and nothing fell off. She's acting fine, walking around and pecking and runs when I come outside. Did she just somehow just get her butt covered in dirt? If so, should I try and get it off. Soaking her bottom or let it come off on its own.