I've got my main mob, 50 plus on permanent open loft and my y/birds, 18, go out every day but are then shut in and my losses are minimal in fact I can't remember when I last lost one, They are fit and react to all wild bird alarm calls, as I do . I feel they would be pretty unfit and soft if I shut them up for weeks so I'll stick to my proven methods and I do think mine are very street-wise, I live in a remote location and have every predator here