duck eggs disappeared from nest, no evidence!

One of our khaki campbell hens went broody so we decided to let her try. I think there were 5 eggs in the nest but we didnt want to check to disturb her. She sat for two days, getting up briefly to eat and drink. This morning she was sitting on the nest and there were eggs in it. We were out all day. When I came home and checked, all the ducks were out in their run. I went to look in the house and there was no nest! It had all been totally flattened, and there were no eggs anywhere, nor any evidence of any kind. The straw didn't look like anything had been digging through it, just looked like normal before the nesting activity. There were no broken shells or anything. It's a metal shed with a concrete floor inside a run. We know there have been rats around but there hasn't been evidence of them for months. There are a few mice about. I know there are crows and magpies around as they eat chicken food (about 200 meters away). But surely if wild birds or rats had taken eggs there would be broken shells? I don't think they could actually carry them away? I looked in all the places the ducks could theoretically have moved them to (but how?!) - but nothing. I'm totally mystified. Where did the eggs go?!?! And if they start laying again, what should I do??

If there were no shell fragments at all, and no egg mess anywhere in the mulch, it needs to have been something that could swallow eggs whole--like a large snake, or carry them off, like a raccoon or a human.

I wouldn't put it past enterprising rats to roll the eggs off and down a burrow, either.....

Thanks. We don't have any large snakes here at all, or raccoons either (in the UK). There are not large predators except foxes and they would have killed all the ducks too. I had a look around and couldn't see any obvious rat burrows though there is growth around the run fence that could be concealing entrances. I'm just totally shocked since we haven't had any problems with broken or stolen eggs at all before, and am particularly perplexed about the fact that the inside of the house looked normal - didn't look like there had been any sort of kerfuffle, or anything digging around, and the nest was just levelled.
Previously, we shut the ducks in in the evening and let them out 8.30-9 am and collect eggs at that time, so very shortly after they have been laid, so I guess it's possible that rats just never had a chance to get interested before. The most logical thing I can figure is that the duck gave up sitting and all ducks were outside, leaving the eggs in the house alone all day, and then maybe the rats made off with them. But they would have had to get them out of the house - 3 feet to the door - and then across the concrete outside the door - another 3 feet - before they could possibly have gotten to a burrow. And it still doesn't explain the nest being flattened.
It is possible it was a human, but seems very unlikely especially as the run gate was all shut up, and the chicken run is much closer to the road and there were 4 eggs in their nest boxes.

By your description, it does sound like a 2 legged predator to me.
Why steal chicken eggs when there are duck eggs to be had?

Thanks again. The gate to the duck run is held on by two bungee cords fastened in a quirky way, and was all normal when I went to get them, hence my assumption that no one had opened it, although it's possible. Hmmm I just dont know.

I went out this morning and there were 4 eggs again (one from each girl), in an attempt at a nest. I've collected them for now, I think unless I can find out what happened I won't let them sit again.

I had a problem with squirrels carrying off eggs, but they'd only take 1 or 2 a day. Do you have a lot of squirrels around? My theory at the time was that they stole eggs for the calcium, and putting out extra calcium in another form would satiate them so they'd leave the eggs alone. I actually found eggs dropped in the yard with tooth holes in them, I guess from when the dog chased the squirrel.

I've never seen a squirrel around here. We don't have very many trees, and we do have lots of foxes.

A fox might be deft enough to mouth a whole egg and carry it off, but why would it when there are whole ducks to be had?

One of our native birds, the weka, is a great egg-lover and seems to be able to carry eggs off.
Got any intelligent, vicious, omniverous birds from the rail family about?
Another one that will sometimes roll eggs back to whatever hell-hole it came from is the stoat, and I wouldn't be surprised if its bigger cousins like weasles are keen too.
They will massacre a whole clutch of chicks, but generally leave adult birds alone.

I just need to ask this since no one else did, and please don't take it as in insult because your probably more experienced than I am but I just don't know. Did you dig around in the bedding material, straw, dirt, or whatever is on the floor where the nest was? Last year I became very dumbfounded after finding a duck nesting outside and then discovering that the eggs later appeared to be gone. It turns out that waterfowl like to bury their eggs, sometimes very well.

No worries for asking, no offense taken! I did dig around thoroughly at first, and since then have completely mucked-out and cleaned the house, definitely not a trace of eggs. Bizarre.

Do you have crows or jays around? When I was in Wales we had a problem with Jays stealing eggs, but I can't remember if he used to take them whole or break them. My son was quite young at the time and managed to catch the Jay in question and insisted on keeping it as a pet. It didn't live long, but I didn't feel like releasing it again.