Why did my female parakeet's eggs suddenly disappear after a month?

If you don't have a male parakeet along with your female, then the eggs are not viable anyway and should be removed. If you're attempting to raise a clutch, I would make sure the egg stays in the nest in the hopes she moves it back over and sits back on it.

That can be normal, yes. You can check the eggs when they are not sitting on them to see if they are viable - eggs that are fertile usually start off very translucent and then become more opaque (darker/more solid color) as the embryo develops inside. (12 days should be enough to see this change.) If the eggs don't seem viable, or the parents stop sitting on them, they can be removed. If they aren't hatched after 3-4 weeks, they are likely not viable and should be discarded. Make sure you offer an extra source of calcium for your female in the form of eggfood or a cuttlebone. This can help replenish the calcium that was used in making eggs and prevent egg-binding (an egg getting stuck) if she decides to lay more.

The average time for gestation is about 21 days. If it has been 28 days, the eggs are either infertile or the time has been miscalculated. It would be best if she was not bred again until she is much older, at least 1 year old.

Yes, female birds can lay eggs without a male around but they will not be viable so should be removed. Males can mate with males, but if you suspect you have a male, and a female, and they've mated and laid eggs, then you probably have a pair (and at least one female). If the eggs haven't hatched in three weeks they are likely not viable and should be removed.

Incubation in budgies is about 18 days from the day the hen begins sitting on The eggs. You are probably correct in saying the eggs are infertile. If there is no male present, they are definitely infertile. Wait until Coco loses interest, then remove and discard the eggs. This will prevent her from laying "replacement" eggs. Remove the nest box afterwards.

It is possible the stress of chronic egg laying may be affecting her appearance and feathers. Remove any nesting boxes in the cage. If she's laying in the seed bowl, use a smaller container that she cannot sit in. Limit Camille's exposure to daylight to 8 hours or less. Use a dark cage cover or sheet to block light if necessary. Use a calcium fortified seed mix. Leave the fake eggs in the cage for at least 4 weeks.

This can be due to inexperience, stress or possibly an issue with the eggs. Provide a nesting box that has a raised edge to prevent them from rolling the eggs out. Keep the cage in a low traffic area away from direct sunlight, loud noise or vibrations and cold drafts.