we who live in a cold climate need to make sure that we have a secure, ENCLOSED-all sides coop for our hens. No expert, but I can't see just a trap as enough to protect in sub below temps. Thick layer of bedding to insulate the floor,fresh water, not frozen, you need a heated bowl or some other way to prevent the water from freezing and fresh feed. You can give your chickens some scratch, cracked corn, bread, before they roost to help them produce body heat to keep them alive during the night. And even a red head lamp when it gets to deadly temps. make SURE you secure a lamp, really secure it to something solid, so that if it gets knocked by one of the hens it won't fall. Protect any hens with exposed skin with an insulated hen apron and bag balm on the skin to insulate it and protect it from frostbite. And last, take a head count at night, make sure everyone is in for the night. I am reading to many threds about frozen birds, breaks my heart, I know some times things happen no matter what, but alot of us, myself included, are new to chickens and maybe are learning as we go, any other tips out there. remember these chickens depend on us to help they survive, I bet a lot of the breeds we have are not native to freezing climates, so we have to help them out.