I have a male and a female cockatiel both very tame and more than 3 years old. They have together laid 6 eggs and are both very enthusiastically brooding. In fact, the male has completely changed personality wise and is borderline manic in his protective instincts. However, I candled all of the eggs yesterday and they all look the same ... meaning none of them are fertile. Is this possible? I've never witnessed their mating. I've never even witnessed the male court the female. I have witnessed the female basically throwing herself at the male who only politely preened her. This strikes me as a weird situation and I'm not sure whether to let them continue nesting.