I have 3 nesting boxes for my 5 hens. They're wood and built based on specs I found here. My problem is that they kick whatever is in the boxes out until it's just wood, as a result I get cracked eggs sometimes. I started with pine shavings and those were kicked out in no time (I do have a ledge on the front of the boxes to discourage this). I switched to straw, and no matter how many times I rearrange it, they kick it around so that it is like a typical bird's nest: straw in a circle around the outer edge of the nesting box and wood in the center. Is there any way to discourage this behavior?