I have five chickens who are currently on their second egg laying season. I have three nesting boxes that measure 12x12x12 and they used them last year with no issue. This year I will get a few eggs in the boxes and also a few in the corner of the coop. The nesting boxes are kept clean and have plenty of shavings in them, and I have 3 so I don't think they are fighting over boxes. Why are they doing this?