I have researched "when do chicks start roosting" and have yet to come up with anyone that has chicks as old as mine that are still not roosting. My 11 chicks, various breeds and all but one are supposed to be girls, were hatched on October 25, 2010...That makes them 21 weeks old yesterday, and they are still not roosting! I have a roost that is about 20" off of the coop floor. The coop is 12' long by 8' wide. Every night, they are all huddled together in the corner, like they were itty bitties, and it was 20 degrees outside! Sometimes, some of them are "roosting" on the lip of a board that holds the shavings in the front of the coop where I open the door, but this is only about 4" off the ground. Occasionally, when I go lock them up at night, Pearl, my White Rock, will be on the roost, and I think "whoo hoo! they are going to start", but she never stays there. I've seen these guys fly across the yard, so I know they should have no problem getting up on the roost. One time, one of them went into the wrong coop (I have another coop for 5 older hens) and she was on their roost board. I moved her, since I knew it wouldn't be long before they started tormenting her. But the fact that she was on their roost was encouraging. Our temps have been in the high 30's to low 40's at night, so not too cold. Not sure if this info helps, but they were in a very large brooder in the house until they were about 10 weeks old (coop wasn't finished) Even though I offered a very low roost in there, only one or two would ever use it, and that was seldom as well. I wouldn't mind them all sleeping on the floor like they do, if it wasn't for the fact that they poo there too, instead of on the poop board under the roost. Any suggestions on why they are still not roosting?