My parents had a rooster when I was growing up – Rodney the rooster. He had the nine lives of a cat, and survived crazy ordeals like being stepped on by a horse. One extremely cold day, my parents found him frozen solid to a piece of metal farm machinery. SOLID. Like, you could touch him and he was stiff and apparently unresponsive, or so they tell me. By the time the afternoon sun came out and started melting away the ice and snow, Rodney was reanimated. He had survived being frozen solid, or so the legend goes…
The moral of the story is that chickens can tolerate cold – or at least the cold hardy breeds can. Adding too much supplemental heat can mean that they are not acclimated to the cold, and may not go outside at all over winter. The worst case scenario is that if you have a power outage, your unacclimated birds will freeze (and may not be as lucky as Rodney). Although our chickens would probably be OK without any supplemental heat (as long as they had deep bedding and could huddle together for warmth), I want to minimize the risk of their combs getting frostbite, and, quite honestly, I want to maximize their comfort. They’re pets as much as they are livestock.
So, how do we take the edge off without making them wusses to the cold? Despite the fact that my wife insulated the hell out of the coop when she was building it, it doesn’t stay warm enough without adding supplemental heat. This is probably because we leave the door to the run open during the day and there are big vents at the peak of the roof that let warm air out and cold air in (ventilation is a top priority in a chicken coop to prevent disease/respiratory infections). When the door is closed at night, the body heat of the chickens alone make it just 1 or 2 degrees warmer inside than out. When it’s -20°C (-4°F), that’s really cold, even for cold hardy birds.
This is why we think it’s important to have electricity to your coop if you want to overwinter in a cold climate (i.e., where it regularly drops below ~-15°C/5°F). We just ran an outdoor extension cord from our shed (which we also added electrical to), along the fenceline, to the coop. An outdoor power bar is mounted to the side of the coop inside a plastic container (my wife’s genius idea). We can easily pop off the lid of the container to plug/unplug anything we want, and the connections all stay clean and dry. We choose to turn on supplemental heat when it hits -15°C. The heater we use is this one. It’s meant to be mounted to the underside of a desk to keep your toesies warm. It has a low profile, and never gets hot to the touch. If the weather is forecasted to drop below -15, I turn the heater on for the night.
To monitor the temperatures in the coop and outside, I use a weather station with remote sensors. There’s one sensor in the coop and one outside (and one in the baby’s room for good measure). On a -20°C night, the coop can be as warm as -5°C (-1°C if we leave the heater on all day before). I’d like to eventually get a thermostat outlet adapter for it so I can set it to only come on when the coop reaches a certain low, and to turn off when it reaches a certain high. But that’s on the birthday wish list for another year.
We have a galvanized steel chicken waterer, and we bought this heated base to set it on. We leave the base plugged in in the winter and it turns on only when the temperature drops below freezing (which is every day in the winter here…). It’s barely warm to the touch so we’re not worried about fires or burnt chicken toes. And I actually found that I like it under the waterer in summertime too because it keeps the drinking trough elevated to keep out poop and bedding.
Eggs are a seasonal product. The eggs we buy in the grocery store in the dark, winter months are from farms that use supplemental light to trick the chickens into thinking they’re still in the long days of summer. There’s a lot of controversy of using supplemental light for backyard chickens. I don’t have a strong opinion either way, but we don’t use supplemental light, and here’s why. Chickens, like humans, are hatched/born with all of the (undeveloped) eggs they will ever lay already in their ovaries. One day they will run dry, just like humans run out of eggs to ovulate and go through menopause. Since we want to keep our hens as pets and don’t want to butcher and eat them after a year or two of good egg laying, we want to stretch out the eggs we get from them. If we used supplemental light, they would lay all through the year, but would dry up at a younger age. Since we don’t use supplemental light, they will only give us eggs in the spring and summer, but they should have many years of laying ahead of them. My mom has a hen who laid intermittently for 10 years without supplemental light. That hen is now senile (but still loved), and seems to have finally retired from her laying days.