How The Winter Solstice Affects Egg Laying

We’ve made it! It’s December 21, the winter solstice. Although I am not a big fan of the shorter day length and winter in general, the dynamics of how our big Earth is put together never ceases to amaze me. Our days will be noticeably longer a month from now, making me hopeful for spring.

How does this relate to chicken-keeping? When the days begin to shorten in the fall, it triggers most laying hens into molt. They stop laying eggs and spend energy replacing their feathers during their molt. They will then take an extended break from laying until the longer day length triggers them to begin again as we head toward spring.

Many chicken owners believe the colder weather causes a hen to stop laying. In reality, how well a hen lays has much more to do with the quality of her diet and the amount of light she’s exposed to each day. Commercial egg producers leave the lights on in the poultry houses for a large part of every day to keep the hens laying for maximum production. To keep laying at peak, the flock must have at least 15 hours of continuous light during each 24-hour period.

The Biology Behind It

A chicken’s “tuning fork” for day length is controlled by a tiny part of her endocrine system called the pineal gland. Located under the brain and in the middle of her forehead near her eyes, the skull is thin enough in this area to allow light to reach this gland. The pineal gland controls a chicken’s circadian rhythm: when she eats, when she sleeps, when she lays an egg, and everything else a chicken does in a 24-hour period. A hen usually only lays an egg during daylight hours and usually lays an egg once every 26 hours (on average, give or take an hour or so). So you can see that in the winter when days are short and nights are long, her 26-hour egg cycle is more likely to be during the night period about every other day.

After the Winter Solstice

Daylight slowly lengthens after December 21 in the northern hemisphere. That means that in most US locations, by around December 25, if we pay attention, we can begin to tell that the days are getting ever so slightly longer. Going forward, we will have more daylight every day until we reach the summer solstice. The chickens also perceive this longer daytime period and naturally begin laying more eggs as early as late January to mid-February. In fact, our chickens are probably more in tune with the lengthening days than we are.

So hang on! Longer days are coming our way, and soon so will more eggs from our chickens.