Duck stopped sitting

[Bushy T]

Hello one of my ducks stopped sitting on 2 eggs and one is busted and one has a small chunk of the shell missing how can I tell how long she was sitting.

 

[EggSighted4Life]

Those look like they were trying to hatch before she quit.

You could break them open and do an analysis on the stage of the embryo. Is either still moving? Did others hatch already?

This was the best example I found so far..
https://www.fresheggsdaily.com/2012/05/great-eggscape-too-hatching-duck-eggs.html