For an old school approach, you can use a candle to check the eggs. However, be careful when holding the candle, as you do not want it to become a fire hazard.
You can also drape the incubator with a black out curtain or a dark blanket so it is dark inside.
Make sure there are no shadows cast on the egg. You want a clear view of the inside of the egg using the light of the flashlight.
Towards the end of incubation, you may also see the duck’s bill developing inside the air sac in the egg. This means the duck egg will soon hatch.
The duck eggs may appear dead during any stage of development, from day 1 to day 27.
If you know the incubation period of the eggs, you should also wait until day 24 or 25 to do the float test. This will ensure the eggs are developed enough for the test.
If the embryo is alive, the egg may also move around on its own in the water. If the egg floats at an angle, remove it from the water and wipe it dry. Place it in an incubator and allow it to hatch on its own.
Just because the eggs are warm does not mean they are alive. You will need to perform additional checks to confirm they are alive.
You will also need to turn the eggs once a day so they stay warm. Candle the eggs with a flashlight as they incubate to confirm they are developing well. Depending on how far along the duck eggs already are, it will take 27 to 28 days for the eggs to hatch in the incubator.
