I had some brown leghorns on .7 acres with a 4 ft tall fence, (3 ft 2x4 wire with two strands wire on top, total 4 ft). a few "ventures" mainly due to the andalusians' bad influence when they were young,but settled right down. I sold them due to my move, and the new home has similar fence height with much less space. That causes problems when they happen to "startle". She also has white leghorns, which for some reason are very calm by comparison. So it depends on individuals, you have to get past the puberty stage somehow, and on the amount of range space as well as fence height/type.