Hi Neoh,
Unfortunately the eggs will not hatch unless the parents sit on them day and night. Usually one parent sits during the day and the other sits at night. So if only the female is sitting on the eggs, the male is not doing his job. He should be sitting on them at night since she is sitting during the day. Gouldians are not always the best parents, and those who breed a lot of Gouldians often have pairs of zebra or society finches and the let those pairs sit on the Gouldian eggs and raise the chicks. Gouldians do prefer an enclosed nest box and not an open nest. If this is your pair’s first try, just let them practice, then remove the box and rest them for a few months, and then let them try again. They almost always fail with the first clutch because they are still learning. You might do some additional research on breeding this species, because most breeders feel there are some specialty foods they should have when breeding.
Thank you for asking Lafeber,
Brenda