I have a pair of cockatiels and i believe they have mated because she laid 5 eggs the first egg was laid on easter april 24th. Both parents keep going in the nest and sitting in the eggs. i had read somewhere that it take 18-21 days to hatch well mine havent yet so i took the eggs out to check them and all i can see is yolk inside nothing else. so if someone can please help on this i dnt know what to do with the eggs or even if there fertile or not...help!! thanks