The incubation period for lovebird eggs is about 23 days for each egg. So since eggs are laid every other day, you should count from the day the last egg was laid, and then leave them for about 5 days past the due date just in case. However, if she has been staying off of the eggs all night, then they will not be any good. They have to be kept warm constantly, and the hen can only leave them for a few minutes. But if they are left long enough to cool off, they will die – if they were even fertile. If this was their first clutch, it’s normal for it to fail – most first clutches are not successful because the pair is still learning. If you know for sure she stayed off of them all night, then go ahead and take the nest box down and discard the eggs. You need to rest the pair from breeding for 6 months. After that you can give them the nest box back and let them try again. You should always remove the nest box and rest the pair for 6 months between each clutch, limiting the pair to two clutches per year. It takes a lot out of the hen to form and lay eggs, so she needs this time to rebuild her health in order to lay healthy eggs.
Thank you for asking Lafeber,