I have 4 pullets (2 Mille's, 1 Wynedotte, & a Speckled Sussex) who have taken to sleeping in the nesting box. The Sussex & Wynedotte are 15 weeks old, the Milles are maybe 12. They will rest on the roosting bar during the afternoon but will have nothing to do with it at night. How do I train them to move out of the nesting boxes? Is it as simple as blocking off the box?