You don't say what kind of eggs they are, but since they are under a duck I'll assume they're duck eggs. :)

The countdown begins when mama starts incubating or setting on the eggs full time. Twelve eggs is a lot, is she large enough to cover them all or do you need to remove some to ensure a better hatch rate? What kind of duck is she?

Velvet ~:>

Even within species the length of time can vary between breeds.

Figure if she didn't become "broody" enough to sit full time on her clutch, that most of the early eggs probably won't hatch. Storey's gives almost two weeks between the time the egg is laid and the time it will have lost it's ability to hatch.

If she lays any more eggs within the next two weeks, and you know when she "took" the drake, then you may want to pull the fresh eggs and either set them under another duck or place them into an incubator.

I have a mallard and a drake. My mallard is average size I suppose. I'm a newbie when it comes to my mallards. I know she is smaller then my drake and she will be a year old in the middle of May. When I found the nest there where 9 already in the nest and that was on the 8th of this month. I done egg check earlier and I have 12. The weather here in Wyoming has been pretty cold and at night it has been below 30. She doesn't sit on them during the day, but she must at night because I don't have any eggs cracked or broken. I do know that she's had the last 3 eggs every other day. The other eight-couldn't tell ya. Sorry if this sounds stupid but I'm really in the dark about all this. I know my mallard's mom had 13 eggs and 9 of them hatched. I'm a small framed person and when I hold my mallard, she is like holding a 2 month old child. From the way the nest is and how she has the eggs positioned it looks like she would cover them. Plus every time I go due egg check they are all in different positions and covered with bark strips and then other days cleared off. Any thoughts?

I looked in my Storey's Guide to Raising Poultry and what it says is the Pekin duck takes 28 days to hatch, whereas the Muscovy duck takes 35. A cross between the two takes 32. Mallards take 26 1/2 to 27 days. The "Runner" breeds of ducks take 28 1/2. The Muscovy is a good setter, while most other domestic breeds are not. The eggs require daily turning, mark one side of the eggs with a crayon or pencil. If the duck doesn't turn them daily, make sure to do so. The nest should be in a protected area, but they will do better if they are moistened. If the ducks have access to a pond or water source what water stays on the feathers when they return to the nest is usually sufficient, if they do not, sprinkle or dip the eggs into lukewarm water for about a half minute each day during the last half of the incubating period. The hen should not be disturbed during incubation, and food and water should be kept near the nest. Remove any hatched ducklings from the nest as soon as possible and place them into a brooder. This will encourage the duck to continue incubating the rest of the eggs. (Remove all broken and rotten eggs from the nest as soon as possible.) Hatching eggs are to be stored at a temp of 55 degrees F, a relative humidity of 75% and at a 30 degree angle. The angle must be rotated daily, as well as the eggs and not kept longer than two weeks. After two weeks the level of hatchability drops. Most chickens will set 9 to 11 duck eggs, while a duck will cover ten to thirteen. Candling of the eggs should be done 4 to 6 days after incubation, and infertile, cracked eggs or ones with dead embryos should be discarded. They should also be candled 3 days before the anticipated date for hatching. The fertile eggs will appear dark, except for the large air sac at the end. Discontinue turning the eggs 3 days before the anticipated hatching date, and do not disturb them anymore than what is necessary.

Hopefully this will answer most of the questions you have. I, for one am not that experienced with raising poultry, so I rely heavily upon sources, like Storey's, for information. I know that Velvet is experienced with poultry and will let you know if there is something I forgot, or that might be in error.

I just checked the eggs and now I have 13. Everytime I check the eggs they are in different positions and have been moved. I also take pictures with my phone of them and that's how I get a really good look at them without disturbing them. I will see if I can get my man made pond cleaned out and that way they have more water than what they have now. Thank you all so much for your help. I don't know what I would have done if you didn't give me advice. I'll let you all know how this all turns out! Hopefully good news. Again thank you!