My three does and buck, plus three kids, have never been fenced simply because I can't afford to feed hay all summer at our prices (and with all the free food why bother?). We are on a dead end road, five acres and the nearest neighbor is a quarter mile away. They have never gone more than about 150 to 200 yards from the house without me with them, but they have ample scrub and I feed small amounts of grain daily. We are heavily populated with coyotes and there have been numerous mountain lion sightings (though fish and game insists they are not here), but they have never been bothered because they are in the shed at night which is literally steps from my porch and the light is usually on. Only the kids tend to get on the car, but they seem to be outgrowing it because I very much discourage it, and leaving the hood half up helps a lot. If you socialize with your goats a little each day they will stay much closer than if you never do anything except milk and let them go. Each of mine (even the kids from about 5 weeks) have a spot they are tied to for feeding, and during and after feeding and milking they get looked over, hooves trimmed when needed, patted and scratched a little and just generally handled a bit. I walk them every day for about an hour up the power lines that are kept trimmed just right for goats! So all these factors have made my 'free range' goat experience work out well. I just try not to leave the front door open!
