Mystery clutch of eggs

My husband went out to cut the grass and found a pile of 7 eggs. They're pretty dirty, so it's hard to tell if they are from our chickens or from the wild ducks that enjoy hanging out in our back yard. If they are chicken eggs, they would not be fertile. If they are duck eggs, they would be fertile. The ducks have been mating in our pool.

Our back yard is not so large that these would have been sitting there long, probably just 3 days at most. It's been raining, so we haven't gone outside much.

What's weird is that the eggs are really light, as if they were empty, but there are no holes or cracks in the eggs. Also, they were found next to the coop and at that location, it looks as though something small had dug under the coop and maybe even pushed these eggs out from under the coop. The chickens cannot fit under the coop. So something would have had to have located and pushed the eggs under there in the first place if that is indeed where they came from. It could just look as if something dug under the coop and it was only the mystery layers who dug up the area.

Candling has done little to help solve the mystery.

Can eggs dry out over time so they would feel empty? Does a fertile egg with a chick feel the same (weight-wise) as a non-fertile egg? I've never really handled eggs once they had a chick in there. Either momma had them or they were snug in the incubator. I hesitate to crack one open in case it's a fertile duck egg. My son insisted on putting them in the incubator. They've been in overnight and don't stink....yet.

Please help solve the mystery if you can. Thanks!

Do they feel kind of soft or leathery? If so, they might be snake or turtle eggs.

Eggs lose moisture through the porous shell. The longer they dry out the lighter they feel. So, yes, old eggs can feel very light. As long as the bloom stays intact they can often go a real long time without going bad.

A fertile egg and a non-fertile egg feels the same, weight and everything else. I think some of the eggs that are not developing tend to get lighter late in the incubator. The developing chicks seem to hold onto more of the moisture. If they have been laying out any time and have not been incubated then there is no developing chick inside. They would have cooled off and died if they had started to develop.

Since they are dirty and have been in the rain, there is a chance the bloom is compromised and the eggs are subject to going bad. The bloom is a coating the hens puts on the egg that helps keep bacteria out. It’s not perfect but it does a pretty good job. Once that bloom is removed bacteria can more easily get inside and cause the egg to go bad. If you are not using the incubator, what do you have to lose trying to incubate them? Sniff the eggs regularly to see if you detect any rotten egg smell. If you do, find out which one it is by sniffing and get rid of it. If they are that light I don’t have much hope for them but who knows? Sometimes life gives you surprises.

Definitely not snake or turtle. I am leaning towards old and dried out. It really does seems as if some animal had possibly hidden them under the coop and then pushed them back out.

I have a trail cam. I think I'll set it up tonight to see if anything is digging around the coop. We had a raccoon kill one of our hens a few weeks ago. That particular raccoon won't be back to bother our girls, but I suppose there could be another one. We got an automatic chicken door so there would be no danger of forgetting to lock them up at night.