All my roos do that, but my Silkie roo is especially kooky about it. He'll go to his favorite nest spot, the NE corner of the coop, and bury himself down several inches in the litter. He'll growl like a dog as he does this, and keeps this behavior up for at least several minutes. Of course, I "help" him by dumping litter on top of him so he's almost completely buried. Instead of a rooster, I end up with a growling mound of leaves and wood shavings that has two beady black eyes glazed in some sort of weird internal joy. He's an odd one, no doubt about that.