Our Chickens are 16 weeks old and the last couple of days they have been digging bowls in the shavings in their coop and covering themselves in shavings. We have had the nest box part of their coop blocked off since we moved them in. They all use the roost to sleep every night so should I unblock the nest box and put something in there. Also what should I put into the nest box? Should I use the same shavings or is it better to put in something else?