Below is a picture of my yard. It is kind of hard to see but hopefully you will get the idea. The coop will be right above the word coop. The big white/gray object above the word coop is a barn. In the picture beneath the barn and to the left of the barn are tall brush. It is pretty thick so I don't think chickens would go through it. The hayfield is about 15-20 acres and continues past the bottom of the photo. The black line I drew is where my lawn/grass meets the hayfield. I want to install some kind of fence along the black line. How long would the fence have to go to keep the chicken from walking to the right in the photo and around the fence? How high would the fence have to be? I own all the land and buildings in the photo but I would like to keep the chickens on the bottom part of the photo. Thanks.