Boxes usually semi-high - like on top of a couple of hay bales or on a shelf in a shed. They stay low with their chicks until they are old enough to come up the tree with them and then the chicks sit under each wing on the branch and they stay like that for weeks, a whole family on one branch. The hens are mixed - some light, some heavier - there was a RIR cockerel who was huge who slept up in the trees all his life until he died at 7 years old. Our lighter hens tend to stay on a suspended broom handle under cover of the car port roof and lay their eggs in the hen house (which goes unused for bedtime). If you're frantic about losing a hen then maybe this isn't the way to do it, but if you are easy going (and realistic) then it's about as safe as you can get, as I said, we've never had trouble with this and it's super convenient. Just keep the house open for those who prefer it, but if you do want some in trees then a helpful we ladder is the way to go with plenty twig rungs on it. Good luck!