My coop has a concrete floor, and I use shavings as deep bedding, and hay or straw in the nest boxes. The birds pull the nest box material onto the floor, and it gets mixed into the shavings. It works fine. When I first had horses, straw was the bedding of choice. Switching to shavings made life MUCH easier! Straw/ hay bedding is much wetter and harder to clean out than shavings! Mary