See here, his nose is at least a tail's length from the higher-up chicken's pooper. I really did measure my biggest chicken from nose to tail tip while she was roosting, and spaced those two roosts according to that measurement, so I'd have comfortable space for her to roost up high (where she...
I am just a suburban pet chicken keeper, so maybe its not the same, but I did measure my biggest hen before making these roosts. Our chickens spend plenty of time in laps, so a poopy chicken is easier to avoid than to wash-n-dry. I made the shelf with roosts above my waist because its hard for...