The answer is - nothing. Chickens are not people. They don't feel the cold like humans do. Think about it: bed coverings we use are often made from feathers. And chickens have plenty of those.
But what if you live in the really, really cold parts of the world? Isn't it necessary then to do something to help your flock?
Certainly. There are many things you can do to make sure your flock is protected against the cold - that's what this article is about.
But what people usually mean when they ask me "how can I keep my chickens warm" is "how should I heat my coop?"
And my answer to that is simple: do these things first. Heating the coop is rarely, if ever, necessary.
Protecting against the cold and, in particular, the damp, is more to do with taking steps to make sure your coop and run are adequate, and your chickens are healthy enough to withstand the pressures of winter.
In fact, it's true to say that chickens are much better able to deal with the cold than with heat. Many people, even in the depths of Alaska and northern Canada, where temperatures can reach as low as -15ºC (5ºF)(1), raise healthy chickens without resorting to additional heat in the coop.
It may be too late if you have an established flock, but if you're just starting out or you're planning to add more chickens, take a look around your area at what knowledgeable chicken keepers choose. Some breeds are better at dealing with cold climates than others.
If you're not sure where to start, my recommendation would be the "ordinary" brown commercial chicken, often known as the Red Star. I have several in my flock and they withstand cold winters in Italy, where temperatures can fall as low as -15ºC (4ºF), exceptionally well.
The resting temperature of an adult hen is somewhere between 40ºC and 43ºC (105ºF to 109ºF). Her heart beats at around 400 beats per minute(2). This high metabolic rate in itself helps keep each chicken warm.
So when the flock is roosted together, they jointly add a considerable amount of heat to the coop without ever having to do anything else. In fact, there's evidence that each one adds the equivalent of a ten watt light bulb to the temperature(2).
This works particularly well in smaller, well insulated coops. Of course, if your chickens live in a large, draughty barn their body heat in itself won't be as effective.
Feathers are what keep our chickens warm. Before winter sets in, chickens moult so that the good quality new feathers will provide excellent insulation during the hard winter months. Their feathers are such good insulators they're being trialled in the UK as a form of home insulation.(3)
Like wild birds, chickens keep their bodies warm by "fluffing up" to trap air between the different types of feather. What you may not know is that fluffing up also includes protection for their feet. In order to do that effectively, their roosts need to be a certain depth.
Make sure your roosts are the right size to keep your flock's feet warm this winter.
Most coops are placed in shaded positions in order to keep cool during the heat of summer. But in winter, the sun can be a friend.
Daylight hours may be short, but there will still be some sunlight during the day. If you have a chicken tractor, or a movable coop like an Eglu (which is also designed to keep warmth in), move it into the best position where the sun can warm it for as many hours as possible during the day.
Alternatively, move the coop into an enclosed space like a barn or large garage. There, you have double insulation.
And if you haven't yet bought a coop, consider buying one that you can move around according to the season.
The biggest danger to chickens in winter is not cold, but damp. Wet feathers cannot provide the insulation your flock needs at this time of year, and wet plus cold equals frostbite.
If your chickens spend more time inside in cold weather, their droppings inevitably build up and release ammonia - which even without damp can cause respiratory problems.
But if the damp from those droppings has nowhere to escape to, their warmth, plus warmth from the chickens themselves, will cause a build up of moisture. And that build-up will lead to mouldy bedding, spores and respiratory problems - in other words, a very sick flock.
To avoid that, make sure you have good ventilation above roosting height. It allows the moisture to rise and leave the coop, without chilling the birds.
Ventilation is one thing. Draughts are another.
While your flock needs a well ventilated coop to allow moisture to escape, you need to make sure that cold air is not blowing directly onto them.
Stand in your coop and test whether you can feel cold air blowing in. Or worse - holes where rain and snow can come through.
Find the holes where the wind is blowing in, and block them. You don't need to go to expensive lengths for this. Old feedbags or some sacking will be perfectly adequate.
If you notice your chickens are wet before you have a chance to block up the holes, take them into the house and dry them out before you allow them out again.
And never allow chicks into the cold before they're properly feathered. They can't regulate their own heat.
The short answer in most cases is "no". As we've seen, ventilation is critical in the winter. Making your coop completely airtight will create a moisture build-up and that can be fatal. It can also provide a cosy sleeping place for pests like red mite to hide.
There are, though, some small changes you can make to keep out the cold.
Using the deep litter method in a larger coop is an excellent way of providing winter insulation. I use it in my large, stone-built coop every year and have never yet had a chicken die from the cold. The temperature is always warm, despite Italian winters being incredibly cold.
Use at least ten centimetres (4") depth of wood shavings, straw or mixed bedding. I use a mix of straw, dried leaves and pine needles.
It's not, as is often said, an easy or "lazy" method - it requires regular upkeep. But it is certainly an appropriate way of retaining heat in cold winter months.
I have a detailed article about using and upkeeping the deep litter method, here.
Bored chickens can easily start to display inappropriate behaviour, pecking and egg-eating amongst them. So you don't want to keep your flock "cooped up" all winter. They need to get out.
But what if the snow is deep and the wind chill, chilly?
Find 25 simple boredom busters for those extreme winter days!
Drinkers freeze easily in ultra-cold weather, but chickens need a constant supply of water to remain hydrated. So it's crucial that you make sure, one way or another, that water remains freely available.
Don't, though, keep water in the coop. You need as little moisture as possible inside, and the flock won't need water during the night. As long as it's available for them as soon as they leave the coop in the morning, they'll be fine.
(This link is an "affiliate" link, which means that if you click and buy something, I earn a small commission at no extra cost to you. Please note: I've never used one of these drinkers since they're not yet available in the EU. However, they have excellent reviews on Amazon).
Chickens eat more during the winter, as they use more energy to keep warm. Foraging becomes more difficult as the ground freezes and there are fewer berries and bugs in the cold. And feed becomes instantly wet as it hits the snow-covered, damp ground.
Take steps to avoid these issues:
In my view, heating the coop is unnecessary, and can prove fatal. As long as your chickens have a weatherproof, well ventilated coop, a sheltered run, and adequate food and water, they will survive the winter without problems.
It's the summer months you need to be more concerned about.
Heating the coop can lead to some specific problems:
However, we all need to make decisions for our own circumstances. Sometimes, people tell me that no matter how persuasive arguments for not adding heat are, they cannot resist adding some form of heat lamp.
In that case, the only appliance I'd recommend is a wall mounted, flat panel radiant heater like this one...
But please - don't make the environment warm. Just lessen the chill in the air. And even then, be very, very careful.
Remember: chickens have thick, feathered coats. They are not people. They do not feel the cold to anything like the degree that we humans do.
Keep your chickens safe this winter.
A lot of "facts" you'll find on the internet are often people's individual views, often based on inaccurate information repeated from poor quality sources.
The information I provide in this article and others is based not just on my own experience, but on evidenced facts from scientific, peer-reviewed research and evidence from highly respected and experienced poultry keepers such as Gail Dammerow.
Some of the sources I have used are these - click the link to read the full document:
1. Wikipedia: Climate of Anchorage.
2. University of Kentucky, College of Agriculture, Food and the Environment: Poultry Production Manual Chapter 7: Air Temperature. Pub. University of Kentucky, 2019.
3. Dowling, S: How chicken feathers could warm our homes. Pub. British Broadcasting Company, 2017.
4. Hayajneh, F., et al: Anticoccidial Effect of Apple Cider Vinegar on Broiler Chickens. Pub. Polish Journal of Veterinary Sciences, 2018.
5. Mahesh, M et al: Natural antibiotic effect of turmeric in poultry management. Pub. International Journal of Poultry Science, 2018.