They are, with some caveats.Thank you everyone. That helps a lot. When I heard wood chips would be good in the run I thought, oh we have that! But then my oldest friend has had chickens for years and years in a plain dirt floor pen (she used to let them out but no longer) and they're fine. So maybe I'll leave well enough alone.
Just let the pile sit, once the run starts stinking they'll be ready to start adding bit by bit.