As I was about to discard this unmotherly female, I remembered her first cock from the previous year. After 5 days the first egg was laid. However, I did not give it much attention, as I had not much ope of success. On the 16th day I became so curious that I had to look and see if any eggs had been fertilized. Now I had to wait and see whether she would kill her young as she had done before.
Budgerigars are very very unpredictable to say the least.