We are new to the backyard chicken experience. Our dozen chickens are almost 3 months old. Their night time coop is contained inside a fenced in area, about 3 ft off the ground. There is one roosting post, and four nesting boxes inside. Chickens can also get on top of the inside nesting boxes to roost. The night time coop has a rope light that comes on at dusk, and goes off an hour later. There is about 3 ft of space on top of the night time coop where the chickens go sometimes. We have been using the bale size pine shavings from TSC since they came to us at 1 day old, and change it all every week, inside the coop and on the floor of the coop. For the last week, they all have been spending the night on top of the coop, that is inside the fenced area. Is it the shavings? Could there be mites? The inside has only 3 days of use inside, so isn't very dirty. There was another light inside, but after the first day of sleeping on top, the bulb light was changed to a rope light that takes NO space away at all. Do we have a problem with the chickens on top or there something we need to do differently?