Lol it's the chicken drawbridge over the moat! That's pretty cool, they have no problem going back and forth over that huh? I guess chicken aren't afraid of heights cause they can fly!
I tend to take the "4 sq ft per bird of coop space" as a bare minimum. The more room they have the better, start crammin them in and problems will arise.
I also wonder if the chickens might broaden their range once they are mature, some/all are only 5 months old?