My large chicken run is about 3/4 of an acre and is surrounded by a 4.5' horse fence (covered with chicken wire and topped with a shock wire for the horse.) My broilers are WAY too fat to fly out. Recently, a 6 month-old spunky Rhode Island Red and Light Brahma have been getting out. Will these breeds eventually grow to be too fat to fly over? I have: Light Feather-footed Brahmas Rhode Island Reds Silver Laced Wyandottes Black Australorps Black Giants White Crested Black Polish (the freebie, which is either too dumb or blind from his crest to even find food in front of him, let alone fly out) All of these birds are 6 months of age. I've noticed that they only fly out when I am late getting them their breakfast, or very late in the day when they may crave a snack. I wonder if the majority of them stay put in the pen because the older, bigger broilers (and roo) always stay put. Also, with such a big area, maybe they have no reason to venture out. I only ordered from the "Heavy Breeds" section of my MM Hatchery catalog to try to prevent having to put up a net. I think netting would take away from the natural beauty of the farm. The advice is much appreciated. Photo taken in September. The babies in the background are much larger now.