Now I am not complaining about the weather as it is well overdue, but I was planning on doing a bit of a chicken run sort. What do I put down on the ground, where the mud has gone really soft....Straw, woodchip, sawdust? The run is outside (not covered, although they have two houses and two shelters) and we have 6 chickens and 4 chicks (who are out with the big birds now!)