I have them in a real tree branch, occasionally one slept up there but tonight all of them did. I don't really like any of my birds sleeping in the nest box. Bc they poop and then that creates mites & your eggs will be dirty. (Unless you clean it everyday) that's just my preference
It's easy to clean the nest boxes every day since we check for eggs every day any way . We haven't had trouble with poo on the eggs in the nest box. The chickens are pretty good about keeping the nest boxes clean. My problem is that they love to scratch the straw out of the boxes!