Yep, she has access to oyster shell, which is the calcium supplement.
I have straw and shavings in the pen, but it's a very large pen, and it would be hard to cover the entire thing (and require LOTS of much harder cleaning that it's getting...)
Also, they are only in the pen at night. Like the chickens, they are "free range", and the ducks like to swim in the pond (she's actually laid a couple of eggs in the pond before 
