Since all the birds are the same age, that leaves issues with the roost. I've moved my chicken shelter, then we all moved, so I've had a bit of practice in making a roost that the hens feel comfortable/safe in. The first enclosure, had roost bars and it was in a trampoline pen surrounded by shade cloth, much like a shady treetop I guess. I did notice, when I "failed" to make a suitable roost in their new enclosure, the birds found their own. {they're in a predator proof enclosure, btw} I corrected my "failure" by putting up shade cloth. Maybe the pullets are saying that you don't have enough shade cloth or other natural cover in the tree tops you've created for them? I have about 18 inches-2 feet between the roost bars and the roof, or the top of the shade cloth, and shade cloth extends down to the level of the roost bar, if that helps. For SW washington and not in Arizona like I am, I'd think you'd substitute shelter for shade cloth.