If your thermometer can hit -20°F and you're wondering whether your hens will make it to morning, this is for you. Well-meant moves like a heat lamp or a sealed-up coop often cause the very problems they're meant to prevent. This is geared toward northern states, where temperatures can drop to -20°F for stretches.

The short version: the birds need to stay dry, out of drafts, watered and safe. They don't need to be warm. Below: heat, air, water, predators, cleaning, and how to check it's working.

Heat

Many people are tempted to put a heat lamp in their coop. Do not do this. For starters, they are a fire hazard. Chickens jump around much more than you'd think, and the odds of them knocking a hanging lamp down or breaking the bulb are high. Broken glass is not something you want to deal with in the coop. If the lamp falls to the floor and does not break, it can burn a hole in the floor and potentially catch the wood shavings on fire! (Trust me, it's happened to me.)

Another reason not to use a heat lamp is that the birds become acclimated to the bulb. Left alone, their bodies adjust as the days get colder and they become naturally resistant to the cold. If you use a heat lamp, they get used to the temperature under the lamp, and if the bulb dies in the middle of the night, your birds won't be able to adjust to the sudden change and can die.

The birds do not need heat. Some people bring their birds inside on really cold days. I think this is a bad idea, not just because of the change in body heat balance, but because of disease. Never bring your birds in the house.

Extension advice mostly agrees. Kentucky says a properly built house shouldn't need supplemental heat (UK Extension AEN-161), and UNH advises against it in most circumstances (UNH Extension). Minnesota differs, suggesting heat below 35°F, installed per fire warnings and never hung by its cord (UMN Extension). What birds do need is more feed: chickens can eat up to 25 percent more in cold weather (UNH, UMN).

Air Circulation

Many people are tempted to seal up the coop in winter to keep the heat in, but it's important to keep air moving. Humidity is a major winter problem. Breath, droppings and bedding all give off moisture, and if that damp air stays in the coop, it can collect on the birds' heads and combs and freeze, causing frostbite. The air should be able to rise and exit through vents along the roof line. Ideally there would also be vents along the bottom of the coop, so air is drawn in low and exits out the top.

The birds must be able to escape a draft. Drafts are what will damage them and ruin their chances of surviving the winter. If they have a nice spot in the coop to perch out of the wind, they'll happily sit there puffed up for long periods.

How much vent is enough? University of Kentucky Extension gives a minimum inlet of 6 square inches per 25 square feet of floor, and recommends adjustable vents so you can open up in summer and close down in winter without creating drafts (UK Extension AEN-161). As a worked example, an 8 x 10 foot coop has 80 square feet of floor, so 80 ÷ 25 × 6 ≈ 19 square inches minimum. That's roughly a 4 x 5 inch opening, and it's a minimum. If the checks below show moisture, add more vent area up high, on the side away from the prevailing wind (UNH Extension).

Water

Birds should always have water available, and in winter that's a challenge because the water wants to freeze. You can buy water heaters at Tractor Supply, but I found a cheap, easy alternative. Take a 12" round cookie tin, put a $5 landscape light that takes a 60 W bulb (from Home Depot or Lowe's) in the tin, and set the waterer on top. It gives off just enough heat to keep both metal and plastic waterers from freezing. We've found that when the temperature gets really low (-20°F), the water needs to be thawed, but that only happens a few times a year.

Any heated base is still a heat source near dry bedding, so keep it on a stable, non-flammable surface, clear of bedding, and follow the fire-risk warnings for anything you plug in (UMN Extension).

Predators

People are tempted to let their birds free range during the day in winter, but trust me, there is no food out there for them. Their best food source is the coop feeder. And with food scarce, predators are looking for easy meals. Foxes, coyotes and weasels get bolder when they're hungry, and they might come into your yard for a feast even when you're standing 10 feet away! There's also less cover: the bushes they'd hide under in summer are bare. Letting the birds free range in winter is just asking for problems.

Also keep in mind that weasels can easily walk through 1" x 1" chicken wire, so if you think your coop is predator-proof, think again. Half-inch hardware cloth is the only dependable protection for a chicken coop, aside from solid wood. Kentucky Extension likewise recommends hardware cloth or welded wire over chicken wire (UK Extension AEN-161). Make sure any gaps over a half inch are covered and secured before the snow falls, but don't block your airflow.

Cleaning

You still need to clean the coop in winter. I know some people like the "deep bedding method," but I think it just invites problems with disease and humidity. Grass clippings never seem to dry out, so piling bags of them in your coop seems like a disaster. Pine shavings or hay can cost quite a bit. I think the most efficient method is to keep your normal cleaning schedule all year. Remove piles of droppings as they build up, usually under the roosts, and replace the bedding every few weeks.

Whichever method you use, the goal is dry litter. Damp bedding in a cold, poorly ventilated coop is the classic setup for frostbite (eXtension).

How to Tell Your Winter Setup Is Working

Check these on the coldest mornings:

  • Look at the inside walls and ceiling. Frost or droplets mean moisture is staying inside, a sign of poor ventilation or insulation (Virginia Tech). Add vent area up high.
  • Smell the air at bird level. If you smell ammonia, increase ventilation and clean up the manure (UMN Extension).
  • Feel the bedding. It should be dry and loose, not packed and damp. If you hang a hygrometer, Kentucky recommends 50 to 70 percent relative humidity. Wetter than that raises ammonia and disease risk (UK Extension AEN-161).
  • Check combs and wattles. Frostbitten tissue turns gray or black and feels brittle, usually at comb tips and wattle ends, and it can reach toes and feet (UMN Extension). Roosters and large-combed hens like Leghorns are most at risk (eXtension).
  • Check the water at dawn. A skim of ice means your heat source isn't keeping up.

If You Find Frostbite

Warm the area slowly. Don't use direct heat like a hair dryer or heat lamp, don't rub it, and don't trim blackened tissue unless it becomes infected, because the dead tissue protects what's underneath. Healing takes four to six weeks (eXtension). Call your vet if you're unsure (UACES), and fix the moisture or draft that caused it. On the coldest nights, a coat of petroleum jelly on combs and wattles can help prevent it (UNH Extension).

Mistakes to Avoid

  • Hanging a heat lamp. It's a fire risk, and the birds lose their cold tolerance.
  • Sealing the coop airtight. Trapped moisture causes frostbite and ammonia.
  • Venting across the roost. Airflow should pass above the birds, not over them.
  • Letting the water freeze. Arkansas Extension calls an unfrozen water supply critical (UACES).

Summary

I hope this helps. If you have any ideas, please leave them in the comments below. Keep those mother cluckers safe this winter.

If a tractor clears the path to your coop, keep its battery on a maintainer through the cold months. For land-clearing on our place, see the CAT 931 water pump repair.