It’s 21 days for a hen eggs, 28 days for duck eggs and 35 days for goose eggs (all approximate)

Two days ago I noticed this duck sitting in the far corner of the duck house on a clutch of eggs that I had watched growing in number for over a week. She has pulled in straw from outside and “feathered” her nest. She started sitting two days ago but don’t count your chickens until they hatch – nor your ducks!