I am not sure if this is weird or not, but leave it to me to have wierd chickens. 4 of mine, I bought them to together as chicks. 2 Black Australorps and 2 brahmas. I had to find a new home for one Brahma, turned out to be a roo. Anyways, they did this when I still had him though too. They sleep in the corner of the pen, outside, all cuddled together. Usually in a pile. I will go out there and one will be buried on the bottom and the others all piled on. They seem to want to be on the bottom. I have seen them shove to get under the others..... I have seen them out there at like 2 in the morning. When I get up, they are usually in the coop by then and stay in until late morning. My Americauna (who I got later and is younger than them) stays in the coup most of the day. I think she's afraid of them. She sleeps in the coup.