Help with Ducks laying eggs

[CnpBackYardBird]

Have a Question about Ducks, We seperated our ducks and chickens for a few days to get chickens used to the new coop. Our 29 ducks(All Domestic) 15 are to young to be laying, 4 are old enough to be laying. the other 10 we are not sure of there age. we rescued them.
This group of ducks is NOT building a nest. Several of them lay eggs together in a hole they dig in the mulch than cover it up flat. Than we find the young ducks sitting on the spot where the eggs are.
I have never had this happen before. any ideas or info?
thanks

 

[HollyDuckFarmer]

I think it is common for ducks to have a community egg drop location. Mine do that.

 

[Going Quackers]

They don't always build a nest in which to lay, that is part of the reason i have skipped nest boxes for my ducks. Now, some of the older birds could be going a bit broody too i have seen piled up eggs before and that is definitely one of the reasons but usually they do build a nest in that case, the covering of the eggs though leads me back to possible site for a clutch, when they are just laying eggs mine don't cover them.