Dave is standing on the base of stone dust... which we'll be adding to, probably up to the top of the first ground post. On top of that, we have construction sand which will be our topcoat. I have two uprooted stumps that we'll place in there for perching purposes, and I'll be adding some sort of trough to put in "chicken salad" cuttings and weeds they'll like to munch on.
The run sits on the edge of swampy land.... so no grass will grow in there. I'll be rotating pots of plants in there.