I have never had chickens before but am seriously thinking about it. I have a large lot in the city with six to eight foot fence around. The only thing is that I have only a 4 foot iron fence across the front. The space between the fence bars is only 4 inches so I don't think that would be a problem for larger adult hens. But would they jump/fly over the 4 foot height. I wouldn't want them to be able to get out near the street in front. Please some of you experienced folks give me some advice. Thanks!!