Uhm, why does everyone seem to 'make' them roost?
What's wrong with them being on the floor?
I'm guessing the whole predator thing might be a reason, but they can jump, some can climb, not too great then, either.
I donno, my young birds just pile on each other and I don't mind. We are surrounded by cattle farmers, the cows like to stomp and charge anything 'dangerous looking', so I don't worry too much about anything actually making it to my yard. There's a busy road they also need to cross w/o becoming road kill, which this time of year, very few are good at escaping.
Either way, whenever I do place them on anything, they give me dirty looks and then hop down, lol.