my chickens did the same thing, we lined the outside with bricks . Sneaky girls lolJust finished lining the inside 14" of the edge of the run with 4" of soil cement, after locking the chicks in the coop with food and water. Those little buggers were trying to dig under the edge boards and were already 4" down in spots! Tomorrow when they try to dig there they will just be filing their nails!