I have 4 buff orpingtons. 2 are only about 7 weeks but my other 2 are just about ready to start laying eggs. I have 2 nest boxes. I have been making them available because once my girls start laying I would like them to go in there. However, SOMEONE, in pooping all in the back of the nest boxes. I have yet to catch any of the girls in there but they leave the evidence behind! They have a roost and yes the roost is higher than the nest box. What am I doing wrong? Do I need to close off the boxes until I actually get eggs? Any advice would be REALLY appreciated.