I live in San Diego with my 6 hens, and I'm a first-timer and new to keeping chickens. The coop was built by the previous home owner, and has chicken wire on three sides, with plywood on the fourth side, and roof and roosts, so it's really open. Do I need to put some plywood over the chicken wire during the winter to reduce drafts, even if San Diego winters are mild? Should I consider any type of heating - like a heat lamp, or a ceramic heater (that I read about on another post) to make sure that they are warm? I have a few nest boxes with straw, but my hens prefer to be to stay up on the top roost, and I get chilly just looking at them. Thanks in advance for the help!