Call duck egg question

[Bantymama]

My call has been sitting on 7 eggs for about a week and a half. When i got got back from camping on sunday there was a egg out of the nest and cracked in half and then yesterday when i got from work there was another egg out and the end of the egg was broke open and all the yolk and insides were gone. The eggs are out of the nest box and about 3 feet away from the nest. My pens are off the ground and critter proof. Any suggestions on what is going on.

 

[AdamD77]

Hmm, could it be that the duck accidentally broke a couple and ate the contents? Not sure why that would leave the eggs 3 feet away though... Could it be a small creature like a rat or is the pen rat-proof?