Out of 15 chickens, who have all been going into the coop at night for over a month... 5 have decided they want to huddle under the coop and go to sleep there. I have to go out every night and pick them up, and place them in the coop. This has been going on for about a week, and although it's dark, and I can't see them well... I think it's the same 5 chickens. What happened? They used to go into the coop at night with everyone else. I thought it might be the yard security light... maybe too bright... but, they aren't wandering around, pecking, like they think it's still day... they are huddling down together to go to sleep. I also have a heat lamp in the coop, since the chickens are so young, and it's cold outside... is it too hot for these 5 particular chickens? The heat lamp has been in there the whole time, the yard light has been there the whole time. And, this new behavior is all of a sudden this week. Any suggestions would be welcome. I'm totally baffled.