You have been waiting patiently for months! You have carefully selected and prepared your pair making sure they are old enough, they have a good breeding diet, and they are in breeding condition. They have had a nest box for some time and have finally started laying eggs! Now the next and most logical question we all ask our selves- are they fertile?
Here are some pictures of my eggs as they develop to help you figure out this very question if you are not sure!
The first couple days of incubation there is no sign of life within an egg.
Infertile and fertile eggs will look the same.
After 2-3 days an experienced eye can start to see development within the eggs center where the ovum is located attached to the yolk. In this picture if you look very close there is a small dot in the center of the egg that is slightly darker.
At 4-5 days it should be obvious if the egg is fertile or not.
Small networks of blood vessels are starting to develop within the egg, and a heart beat can often be seen at this stage.
At 7-8 days the embryo is growing larger and starting to fill the egg, causing the whole egg to get a pink tone.
At 10 days in development the egg starts to darken with the growing chick.
By 13 days the chick is starting to take up most of the egg. Often you can only see light going through the top near the air sack
By this stage the chick is taking up nearly the whole egg. The whole thing is very dark with no light making it through the egg. Only a few more days and the will be ready to hatch!
Picture 1. A clutch of infertile eggs.
Picture 2. Here you can see 1 fertile egg at 4 days of development. The other 4 eggs of this clutch are not showing any signs of fertility so far.
Pictures 3-4. Here you can see a clutch of all fertile eggs with each day of development.
Pictures 5-6. Here is another clutch of all fertile eggs with each day of development.