The days are quickly getting shorter here in the northern hemisphere as autumn takes hold. What that means for a lot of chicken keepers is a sudden drop in egg production. Like plants and many other animals, a chicken's biology is attuned to the change in day length over the seasons.
When days get longer in the spring, this triggers the hens reproductive cycle to lay lots of eggs, since spring and summer are great times of year to raise chicks. As the days get shorter, egg production slows down, since raising chicks in the winter is generally a bad idea for a mother hen.
Here in Vermont at 44 degrees north, we see some extreme shifts in day length. Our shortest days in the winter see less than 9 hours of daylight and our longest summer days are around 15.5 hours. That means that without supplemental light, chickens are really not in the mood to lay eggs in late fall and early winter.
Supplemental light is an easy solution. If the hens are provided with 12 to 14 hours of daylight they will lay eggs much more consistently throughout the year. However, I hear all kinds of reasons from small scale chicken keepers why they think it's detrimental to provide extra light for chickens. Let's address some of them here.
It's 'unnatural'
I am all for natural solutions to livestock issues when possible. Rather than using drugs to keep my chickens from getting sick, I let them forage, dust bathe and eat healthy foods. Instead of deworming them with chemicals, I use frequent moves to fresh ground in the summer and lots of fresh bedding in the winter to keep them away from parasites.
But I also do a lot of "unnatural" things that are in my chickens' best interest. I protect them from predators with electric fencing, I purchase nutritionally balanced feed for them to eat and when they're chicks, I raise them in a heated indoor brooder.
There are no negative health effects for the hens when providing extra lighting in the winter. I know this from experience raising a lot of chickens and also from my inability to find any studies that demonstrated ill effects. So while lights are unnatural, I have no problem using them to tweak a hen's natural biological cycle to my (and my customers') advantage.
'The hens wear out faster' or 'the hens need a rest'
This one is straight up a myth. If your hens are starting to look unhealthy or lay thin shelled eggs, it's not because they need a winter break, it's because they need better nutrition, healthier conditions or parasite management right now!
Productive laying hens need plenty of calories, balanced vitamins and minerals and access to a good source of calcium like oyster shell grit. Parasite loads either internally from worms or externally from mites can also lower a chicken's egg production. Keeping hens on the same piece of ground for long periods of time means worm eggs have a chance to build up. Lack of access to dust bathing and nutritious foods can allow mites to take hold in a chicken's feathers.
Hens also have a limited period of good egg production. After 2-3 years, no matter how well a chicken is treated or how long of a winter 'rest' she gets, she will lay far fewer eggs than those first few seasons. Providing light in the winter does not shorten this period of good egg production, since it doesn't speed up the aging process.
The hens will run out of eggs faster
A related myth I hear is that the hens will 'run out of egg faster' if they lay year round. You might remember from biology class that a female of any mammal or avian species is born with all the eggs she will ever have. This is true but that does not mean that a lack of eggs is why chickens stop laying. It has much more to do with aging, health and hormone production. A hen is in fact born with far more eggs than she will ever actually lay.
It makes them more aggressive
There is a little truth to this one in that if you don't do light the right way, it can negatively impact hen behavior. The first rule is not to provide more than 16 hours of daylight in a 24 hour period. This can lead to aggression and feather picking since the hens aren't getting enough sleep!
12 to 14 hours of total light is the sweet spot, so when providing light, you will need to keep track of how much natural daylight there is in your area and add on accordingly.
Another reason for aggression is simply boredom. There's a lot less for chickens to do in the winter, especially if it's cold and snowy enough that they don't want to leave the coop. For lack of anything better to do, they may start picking on each other. (Read more about handling aggression in laying hens in my article here). So it's important for your hens to have something to scratch through like hay or vegetable scraps to keep them entertained.
They won't roost naturally
This is another one with some truth to it but again, only if you don't do winter lighting the right way. If you add light in the evening, the chickens will be out and about, scratching and pecking when suddenly, the light goes out! Now it's pitch black and they don't know how to get home to their roosts.
The better way to add light is in the morning. For example, on our shortest days when the sun sets around 4:30pm, I have lights on a timer that come on at 3am. By the time the lights go off around 7am, there is enough daylight that the hens can see what they're doing. In the evening they go naturally to their roosts as the sun goes down.
Fire risk
This is one issue to take very seriously. Running electricity into your coop does carry some risk, so it's important to take steps to reduce that risk. For a start, a light bulb is far less dangerous than a heat lamp. This is actually one of the main reasons why I do not heat my coops in the winter, though I do provide light.
Heat lamps draw much more electricity than light bulbs and produce, obviously, more heat. Combine that with active flapping birds, dust and dry bedding and you have all the ingredients for a fire.
There are steps you can take to reduce this risk though. Always make sure lights are well secured and protected from breakage by birds. Avoid using extension cords and plug into GFI outlets.
How to use lights
So, if you'd like your hens to continue laying well in the winter, provide them with enough artificial light to give them a total of 12-14 hours of daylight. The spectrum of light is not that important and for most coops a single 60 watt equivalent light bulb will do.
Do remember to keep an eye on the day length in your area as winter progresses. After the solstice in December, the days will be getting longer, so you will occasionally have need to reset when the lights come on to avoid giving the hens too much light.
If it's already late autumn or winter and you'd like to introduce supplemental light, be sure to add light gradually, not all at once. A sudden change in day length can stress the hens and decrease their lay rate even more! Adding about 15 minutes of light per week is a good pace. Though once again, don't forget to account for natural shortening of the day. You may need to add more than 15 minutes to your timer each week to make up for earlier sunsets.
Even with lights, don't expect your hens to lay eggs like it's mid summer! I am quite happy with an average 80% lay rate over the entire year. For me this means the hens lay at a peak of 90% to 100% during the summer months and then drop to 70% for much of the winter. During particularly cold weather they may drop to 60% but not for long. Keep in mind that these figures are for 1-2 year old hybrid hens (Golden Comets) and older hens or heritage breed hens will not do as well.
Sources:
See the section "Light management for year-round production" - https://poultry.extension.org/articles/poultry-management/raising-chickens-for-egg-production/
Handling Aggression in Laying Hens - from Fat Chance Farm