I keep hearing about the need to manage the humidity level inside my incubator.  Why is that important? 

We hear this quite often and it’s actually a great question.

In nature, the mother bird does a really good job keeping the conditions of the egg just right so the fragile embryo inside can develop as it should.  One of these conditions is the moisture that the egg is exposed to.  In an egg incubator, we call this the "relative humidity" level.  Or just RH for short.    Let's mention just briefly what it's call "relative" humidity.    

Two of the main factors that affect the the amount of moisture the air can hold are temperature and atmospheric pressure.  It’s not easy to control the atmospheric pressure, but the temperature is something we try very hard to control in an incubator.  As the temperature goes up, the amount of water (or moisture) that the air can hold (in the form of vapor) goes up.  As the temperature falls, the amount of moisture the air can hold goes down.  That is why dew forms on grass on a beautiful summer’s morning.  The temperature of the air decreased during the night so the air could not hold as much moisture, so it condensed into water droplets and we notice it on the grass. 

So why control it in an incubator?  An egg needs a certain amount of moisture to keep the egg from drying out too soon.  If it dries out too soon, the chick will not have the lubrication it needs to move around enough when it comes time to pip.  This will cause the chick to get stuck, not be able to break the shell lid open and eventually it will die.  But we also have to make sure there is not too much moisture.  Otherwise there will not be a big enough air pocket for the chick to breathe in as it pips.  So the right amount is very important. 

So how do I control it? 

Most incubators come with a simple way to manage the humidity level.  Most of these ways have to do with adding water to built-in water trays on the bottom of the incubator.  They may have several different trays so the more of them you fill, the more moisture there will be in the air.  In home-made incubators, any dish can act as a humidity tray.  In order to increase the amount of surface area (and thus increase the amount of moisture that gets into the air) you can add a sponge or a cloth to help wick the water up and allow more of the water to evaporate into the air.  Or you can simply add more containers to increase surface area.

Surface area and humidity

You will find that a simple hygrometer (like a thermometer, but used to measure humidity) can be very helpful to manage the humidity level in your incubator.  You can purchase a hygrometer for very little investment.  And the returns can be very good!   

Thermometer and Hygrometer

But for those who would like to take more control of the humidity level in your incubator, a hygrostat may be the answer.  This is like a thermostat but instead of regulating the temperature, it regulates the humidity level.  This is a more complicated topic and will be addressed in a different blog post.