I found an egg shell on teh dam yesterday. Good news bad news scenario. Good news was it was on land, bad news the raccoons found it before I did. It is tough to know when to go look. I know peeps on the duck forum say their girls always lay in the mornings but I don't want to walk over there to look and disturb them. By the time they move to another area my days have started and I can't look till around 2 ish.
Not sure about duck eggs because I haven't ever set brand new fresh eggs before but with chicken eggs I think I could tell by day 3.
https://www.backyardchickens.com/threads/kikis-found-horse-eggs—experiment-round-2.1237847/#post-19864440