Do you have to a male cockatiel fertilize female cockatiel?

Yes, a male cockatiel must fertilize a female cockatiel in order for her to lay fertile eggs. The male cockatiel's sperm fertilizes the female cockatiel's eggs internally, after which she lays the eggs and incubates them until they hatch. The chicks that hatch from fertilized eggs are genetically related to both the male and female cockatiels.