Turtle Egg Incubation
There are many different types and breeds of turtle, so determining the right incubation duration of turtle eggs, as well as appropriate humidity and temperature can depend on many different factors.
You will want to start with a clean and sterile incubator. Many choose to wash there's with a low bleach solution, while others choose to purchase and use commercial incubator disinfectant. Either way you go, it is important to make sure you clean all the surfaces inside the incubator, as well as any surfaces you may touch when using the incubator, such as buttons, handles, etc. Wiping these with a cloth with the disinfectant should do the trick.
Next you will want to set up the temp and humidity. You will want to let the turtle egg incubator run for about 24 hours prior to introducing your fertile eggs so that your incubator is move-in ready for your eggs.
You will most likely want to use vermiculite, perlite, or some other type of substrate to partially bury your eggs in. Sand is not recommended, as it does not allow for the eggs to get the needed oxygen as readily.
Prepping Turtle Eggs for Incubation
First, you will want to carefully remove them from their nest. The soft-shelled varieties of turtle egg can be especially delicate, so using a paintbrush or clean toothbrush to remove the substrate from the tops and sides of them can help you get better access to the eggs. Unlike poultry, you will want to make sure you DO NOT turn your turtle eggs during incubation. Once the embryos have started to develop, turning them can twist the embryo, resulting in loss of the turtle. Many people use a pencil to draw an "X" on the top of each egg so they can make sure they place it the same way in the incubator as it was in the nest.
For most species, the ideal temp range is around 85 degrees F to 90 degrees F. Of course, there are variations to this as well, especially if you choose to "temp sex" your turtle eggs- basically, if you incubate on the lower end of the spectrum you will have mostly males, while the higher end produces mostly females, and mid-range temps producing a blend of both.
Temps that are too low can still incubate, but may take much longer to do so than those closer to the acceptable range. Temps that are too high can lead to deformities or even death of your embryos.
For hard shelled eggs, a humidity of about 70% should be sufficient. However, soft-shelled eggs require a much higher humidity, closer to 90%, to hatch correctly. The American Box Turtle egg, for example, would need to incubate at that 90% mark since they lay a very soft-shelled egg. The soft shelled eggs have greater chance of deflating, and often naturally lays in a more humid area, such as forest floors and near water sources. Species that produce hard-shelled eggs are more often in dryer environments such as deserts.
Incubation duration can vary greatly. Most species will hatch between 8-11 weeks, however it can take 18 weeks or more. It can also vary greatly between eggs in the same clutch. They should start hatching around the same time, but don't toss any eggs out until you have given them all ample time to hatch, and are confident that they are infertile. Just one clutch of turtle eggs can have a hatch date variation of up to 18 days, and can be even longer than that in some tropical species. This can even happen in very stable and accurate incubators, and although it is unlikely that you would have such a range, is something to think about when making the decision that the hatching is done.
The best thing about incubating turtle eggs is that when you are done, you have baby turtles! Having seen many different types of animals hatch from eggs, there is nothing quite like a turtle nose poking out of an egg to really make your heart melt.