Rooster won't leave roost?

[Gail in MN]

I am new to chickens, and got a dozen easter eggers off Criag's List. They are now 13 weeks old (had them since they were a week old), and I'm pretty sure I have 6 hens and 6 roosters-a couple are questionable. There is one guy that just this week started not wanting to come down off the roost. Every morning I let them out to free range, and Sunday he never came out. I didn't know if I should force him to come down or not, so I left him, thinking he would eventually. Monday he came out, ate and drank, and straggled behind the flock most of the day, so I thought this was done. Well, he won't come out again today, and now I am getting concerned. Why would he do this? I wouldn't be so worried if he just hung around the coop instead of free ranging with the others, but he won't even come down off the roost--AT ALL! Should I force him? His health seems fine. His poop looks normal, he is moving fine. He just sits there, but will stand when I come to check on him. What should I do??? Here he is:

 

[chefchick]

I have a baby roo who does the same thing. the older hens and th epullets his age are mean to him. He's at the bottom of the pecking order. I think he stays on the roost so he isn't chased around so much. I try to put him on the floor when I am in the coop so he can eat and drink, but he usually goes right back up. H emust eat at other times, because he isn't really skinny, so I am not too worried just yet. I only see him outside after the oldest hens are in for the night.