when considering roost bars, my learned advice is to make sure roost bars are far enough from one another so when a chicken jumps down (or gets pushed down), they dont have a chance of injury. I am speaking from experience. I have a hen Rosie that like to march (literally her legs appear to be marching) back and forth across the roost bar daring any chicken to jump up. When they do, she pecks them until they jump off. I had two hens with injured leg before i realized the cause. I since have removed one of the bars. Now I have 3 of my 5 hens sleeping in the nest boxes. Only problem with that is the morning poop clean up. Whatever hens, sleep where you want. fortunately as an ol' lady I can still maneuver difficult locations.