I have 3 mallard rescue ducks 2 females and a drake. One of the females started laying eggs in fact 24 of them. She layed a clutch in October and that yielded 8 but I was told that was a practice clutch since it was the first lay. So then a week ago she made this beautiful nest and layed 24 she has been sitting on them 24/7. She did not do this with her practice clutch. Is it possible these new eggs could be fertile? And I haven't seen her get off the nest to swim,eat, or drink should I be concerned? I did put food and water near her nest.