Cockatiel egg

Question
My pair has decided to lay again, and the first egg seems transparent. Even without a light, I can see an air sac at one end. The air sac looks normal sized.

Is this anything to worry about?

Answer
Hi, Andrew,

No.  Every egg has an air sac at the big end of the egg.  This air is what the developing embryo breaths during the 24-48 hour hatching process.

Eggs are visually transparent when first laid.  When the parents start incubating, this is when a baby either starts to develop inside the egg (or not, if the egg is not fertile).  Therefore, as an egg is incubated and a baby fills the inside, the egg will become darker to the eye from the outside.  This is one trick to knowing whether an egg is fertile or not without candling them.  Also gives one an idea how recently an egg was laid just by looking at the eggs.

Chrys