If you do want to do the shavings though. You'll have to do large cut shavings to keep them from swallowing them. But like I said hay would be your best bet. Cause the dust in the shavings chickens are really sensitive to.
Personally I would just use hay to be on the safe side. Since birds ain't the smartest things. They tend to eat the shavings and will get an impaction from it.