By: Tate Beavers and Nora Ferrante
Most chicken eggs take roughly 21 days to hatch, though some breeds (e.g. Seramas and Icelandics) can hatch out sooner. Other species of fowl will have unique incubation and lock down times but will share roughly the same requirements. Some folks allow their duck eggs to cool down or “breath” outside the incubator for 10 minutes a day.
Upon the eggs’ acquisition or arrival, allow them to come to room temperature and rest for 12-24 hours before beginning incubation. If the eggs are older opt for the shorter rest time to help preserve viability. Seal any cracks in eggs with unscented candle wax to prevent bacteria from entering (candles that burn at low temperatures are preferable). Many sources suggest using beeswax for this task, and while I personally think it melts at too high a temperature, use your best judgement and do what’s right for you.
Candle the eggs to make sure the air cell is stationary on the blunt end of the egg; the rest period should help it reattach if it was detached during shipping. When a hen lays an egg she gives it a coating called a “bloom” which prevents bacteria from entering the egg. Washing eggs not only removes the bloom, but can cause the egg to draw in bacteria through its permeable shell and as such it is important to select clean eggs to incubate. The eggs you select should also be of relatively uniform shape and size, and any major outliers discarded. Bearing all this in mind, studies have shown that spraying the eggs with 3-5% hydrogen peroxide can slightly increase hatch rates, though the practice is patented.
The incubator should be placed where there is good airflow and a stable temperature. Still-air incubators should be kept at 99-101º Fahrenheit or 37-38ºC (with the thermometer on top of the eggs for the most accurate reading), while forced-airs should be at 99-100ºF (ideal of 99.5ºF or 37.5ºC).
If temperatures are too low your chicks will take longer to hatch and you'll have a lower hatch rate. Many people and sources will give you varying ideal temperatures and humidities and the more you incubate the better idea you’ll have of what works for you and what gives you the best hatches. As most still air incubators will have hot spots, eggs should be rotated (reorganised within the incubator) periodically to ensure even heating. If you’d like to make a cheap fan for still-air your incubator you can check out this guide. A chicken egg must lose nearly 12-14% of their water content before hatch. Incubators should maintain 55-65% humidity from day 1 till lockdown (other fowl may require lower humidity levels). Humidity should be increased to 70-75% at lockdown to prevent chicks from becoming stuck to their shell. Some species like quail will need lower humidities of between 25-65%. Do your best to maintain humidity for the duration of lockdown, bearing in mind that the incubator should be kept closed if at all possible. (Compare your egg’s air cells to the image. If they are significantly smaller you’ll want to raise the humidity, and if they’re larger you’ll want to lower it).
After 7 days the eggs should be candled; remove any eggs that show no signs of fertility, as they can rot, or even explode and potentially contaminate the fertilized eggs (if it is unclear whether an egg is fertilized, it can be incubated for a few extra days and candled again for verification, at this time I will usually discard any eggs with notably stunted development). You may decide to mark the placement of the air cell with a pencil periodically. This is to ensure the chick does not pip too far away from the cell. If a chick does so, it may require help hatching or a safety hole. With eggs that are smaller, have thicker shells, or are heavily patterned, it may prove difficult to successfully candle the eggs or mark air cells.
If you don’t have an automatic egg turner, place the eggs in an egg carton with the pointed ends facing downwards. Place something under one side off the carton so that it rests at roughly a 45º angle and turn the eggs by simply changing which side of the carton is propped up. Turn the eggs an odd number of times a day; eggs should never be placed on the same side two nights in a row. Duck eggs are better off being hand turned, as some report higher hatch rates with this method.
At lockdown day (day 19 for chickens), remove the eggs from the carton or turner, lay them on their side, and discontinue turning the eggs. This will allow the chicks to move into position and pip correctly. Do not open the incubator from this point forward, as this will release the humidity necessary for the pipping of the eggs.
A chick "absorbs" the remaining yolk into their bodies shortly before hatch. This yolk sack will sustain them for up to 3 days after hatching before they need food or water, so you shouldn't worry that the chicks will get hungry before this time. The incubator should be left on at the same temperature and humidity for roughly that long; leaving the incubator will give any remaining unhatched eggs the opportunity to pip. Opening the incubator early can cause unhatched chicks to become “shrink wrapped” in the shell membrane and render them unable to hatch unassisted. If I absolutely have to open the incubator to help a chick to add water at this time I keep a spray bottle near me and mist the inside of the incubator in order to maintain humidity. Some eggs can be piped and zipped (the process by which a chick pips all around the shell) within a few hours and others can take several days.
Some chicks that have trouble hatching might require a safety hole in order to survive. It’s up to the individual to decide whether or not to assist a hatch. Some folks consider it unnatural or think that the chick couldn’t hatch because it is weak and assisting it could give you a weak bird or weak genetics. Personally I disagree. Not only is the way we hatch out chicks inherently artificial - in nature mother hens are known to assist hatching themselves. You can find more information about assisting a hatch detailed here.
Allow newly hatched chicks to fully dry inside the incubator before removing and placing them under a heat lamp. The temperature under the heat lamp should reach approximately 95ºF (35ºC) and should be lowered by 5ºF (about 2.8ºC) per week until the chicks are fully fledged at about 1 month old. The chicks’ enclosure should be spacious enough that the chicks can move away from the heat lamp if it grows too hot, but should not be so spacious that chicks are completely out from under the light. Make sure that the watering dish is not big enough for chicks to drown. Many companies offer special waterers for quail chicks with a smaller lip to prevent them from accidentally falling in. Chicks are clumsy so never trust that they'll stay out of trouble on their own.
Artificially hatched chicks may need their beaks dipped in water at this point so they understand how to drink. You may also use your hands to “peck” at their feed to help them learn. I personally think it’s pretty cute to watch them imitate you.
Hatching eggs is a fun and rewarding process that is an ultimately variable experience between every individual. Everyone has their own way of doing things and almost everyone will agree to disagree on best practices in any given area depending on their circumstances. This guide is based on personal experience and research but in no way claims to be exhaustive OR the only "correct" way to run a hatch. After gaining some experience you'll find what works best for you and make adjustments from there. I very much encourage research, making mistakes, and having fun with this process. Happy hatching!
Fun facts about eggs - The spot on the yolk called the “germinal disk” becomes the chick which grows veins to absorb the yolks nutrients. The “albumen” or “white” functions similarly to amniotic fluid in placental mammals, it prevents the yolk from becoming damaged if the egg is bumped around and cushions the chick as it develops. Nutrients in the albumen are also absorbed by the chick. Surprisingly enough, the chick will also draw nutrients and calcium from the shell of the egg. In essence, no part of an egg goes to waste.