My chickens are in a movable chicken tractor. When they get out to free range (very rarely due to loose dogs and hawks) they immediately run under my Leland Cypress tress and have a lovely dirt bath. What can I put out in their pen for them to take a dirt bath in? Since I move it to fresh pasture every other day they never get a good dusty spot going before it's moved. I was thinking a kitty litter pan with something in it--cedar shavings or something? Would they even use such a thing? Anyone have a "bath box" in their coop for hens that can't free range? Thanks!