Nesting boxes

My dad made these beautiful nesting boxes for the hens. During our storm, we hung them in the pen. The chickens treated them the same as the perches. I had to take them up to the boxes. Now they seem quite comfortable with them. Someone is nesting in them; although, I find my roosters tend to do more of that than the hens. What a funny group they are.
I put way too much hay in the pen so they are having a blast scratching through it. I'm not sure what they are searching for. I feed them, but they are hard at work. 
Is there a chicken whisperer who can help me understand my crazy birds?