Hens cracking their own eggs

[Shezadandy]

My cracked egg issue didn't start until a good 2 months into laying. Their temporary setup while I was building the big coop had a plastic high-sided cat litter box filled with straw- never had a single egg cracked, broken or otherwise harmed with 10 girls using 3 of those boxes. The problem started when they moved into their permanent coop- the new boxes had plywood bottoms.

During their first week in the permanent coop, they were confined to their new coop without access to the run (an 8ftx12ft full sized shed). They made a huge party out of stripping all the nest boxes of the straw which left the bare plywood- I spent a lot of time sitting and watching, fearing there was an egg eater on the loose. Instead the cracks were being made by eggs getting stepped on- girls were gripping the eggs with nails- then stepping on them- and no straw to cushion left the damage. Did have a couple with the kind of hairline crack you get if an egg slips out of your hand a couple inches over a counter- enough to cause air bubbles to rise when submerged into water. Once the right kind of material they couldn't easily dismantle was in there the damage stopped- and of course being back out in the run helped!