Ours have completely demolished the grass in the run, that was done within two weeks of them moving in there (and to think I mowed/weed eated afraid there would be too much grass in the run!). However we still have a lot of yard - bare spots that are there are mostly from 3-4 years of drought plus where people who owned the house before us used to park in the front yard. Keep in mind though we only have ~15 chickens at a time and they have up to 5 acres to roam... I doubt they ever get further than 100 yards from the pen though. Now my upper garden that's closer to the pen.... yeah, that we're having trouble with.