So I'm in Denton Texas area. Your chickens are fine being out of the coop during the summer especially, its just so hot but please make sure the run area is tight like Fort Knox against predators. However, in the winter you will need to pick them up each night and put them in the new coop (need to get either a Sunrise/Sunset door on it or a door you open and shut each day) until they either do it on their own and most will (but I have 3 or 4 that refuse to go in the coop, they'd rather be up on a kennel door, so when it's freezing i pick up their rebellious butts and put them in the coop every night until the temps get up. Rats especially need water every day, a mouse can go a few days without water, so empty your water bins every night (I dump mine in grass so there's no little ponds for the buggars to drink from) and put your food up every night (I put them in a metal garbage can). If you have one mouse, chances are you have many more....but then again maybe you're lucky and this guy found his way to your house. I free range mine so any mouse can walk into their big pen or coop and as a matter of fact I found mice in the hay bin. Nasty varmints. I have no bleeding heart for an animal that will hurt my chickens. I use the electronic devices, poison and sticky traps. Good luck
@LMVB, I'm rootin for ya.....