I have 5 9 weeks old chickens, and they are in a "2 story" coop. The bottom is an 8x4' run section and the top has a closed in roost area with 5 roosts, and a wire roost area for when it is hot outside. They like to sleep in the closed in section because it is dark, but they sleep on the ground and not the roosts. I know they can get up there because during the day time they sometimes hop up onto the roosts in the wire section with no problem. Do they have good enough sight to see the roosts when it is dark or do I need to put a light bulb in there?