Do we have any chick yet? I am still waiting for some updates. They are long overdue.
The budgies do not exactly get the manual on "how to breed". Although they have some kind of instinct from maybe the genetic memory, they have to figure it out themselves on small details. Some of them might be able to do it right the very first time, some others will have to learn from their own experience and it might take several tries before they can successfully breed.
If the eggs won't hatch, from what I heard you can just remove them and the hen will lay another batch pretty soon. Maybe better luck with the next batch?
