Chickens with red backs ,butts,and losing feathers. no sign of mites,I've checked at night, in the morning, during the day. They are all clean of bugs. I got rid of 1/3 of my girls(2 weeks ago) thinking it could be over crowding ,they still look the same. The next problem is the run smells like a swamp full of poo. Its a dirt run with hay that I lay over it .they do bury the hay I'm wondering if that cause it to decompose and is whats causing the smell. How do you keep you pens from smelling now that it is summer (my coop is fine I change the wood shaving ever couple of weeks as needed). This is my first summer with chickens.HELP!