A SECRET WEAPON FOR FERTILE SWAN EGGS

I'm no qualified on swans. I somewhat believe that a night-time predator filched the eggs. I've read individuals mention that their birds( chickens, geese, whichever) get rid of infertile or nonviable eggs from their nest. In 40 several years I have not had a chicken take away their own egg/s with more info the nest other than accidentally. For la