Duck Egg Development Day by Day: From Setting to Hatch

What the timeline is built from

Three sources, and only three. Cornell University’s Duck Research Laboratory publishes the incubation schedule commercial hatcheries use for Pekin eggs: the temperature and humidity, turning at least four times a day, candling on day 7, transfer to the hatcher on day 25, the humidity rise at pipping and the removal of ducklings when 90–95% of them are dry. Metzer Farms, a large waterfowl hatchery, publishes candling photographs day by day and describes what can be seen — the first structures around day 5, movement by day 12, an egg almost filled by day 22, the bill moving inside the air cell on days 26 and 27 — along with how a duckling gets out of the shell and when to help. The British Waterfowl Association gives the weight-loss target across incubation. Every milestone on the page names which of these it comes from.

What the timeline does not do is invent a day for anything those sources do not give a day for. There is no published day-by-day embryology for duck eggs comparable to the chicken charts, so the “inside the egg” entries are Metzer’s candling observations and nothing more. If you want to know what a duck embryo looks like on day 9, the honest answer is that nobody has published it in a form we could cite.

Other kinds of duck

The schedule is for 28-day ducks — Pekin, Rouen, Khaki Campbell, Cayuga, Welsh Harlequin and most other domestic breeds. The tool also knows the terms the hatch date calculator uses: about 29 days for Indian Runners, 27 for hatchery mallards, and 35 for Muscovies, which are a different species. For those, the early milestones stay on the same day numbers and the last five — transfer, internal pip, external pip, hatch and removal — are counted back from the expected hatch, because that is where they sit in Cornell’s Pekin schedule (three days before hatch, two, one). No source publishes a separate Muscovy schedule, and the page says so rather than pretending.

The two checks that matter

Candling tells you whether an egg is alive; weighing tells you whether your incubator is set right. Metzer’s rule for candling is the clearest in print: clear, distinct veins in living orange and red mean a live embryo, and no clean vessels with a yellower cast mean not. Cornell candles on day 7 and again at transfer, removing the clears and the dead. Weighing is the humidity check: Cornell’s eggs lose about 14% of their setting weight by day 25, and the British Waterfowl Association’s about 15% across incubation. Too little loss means the air is too humid; too much means too dry. The egg weight-loss tracker plots your weigh-ins against that line, and the incubation guide explains the settings and where the published figures disagree.

After the hatch

The timeline ends when the ducklings are dry and out of the hatcher. From there, the duckling age planner gives each week’s brooder temperature, water depth and feed, and raising ducklings week by week is the long version. If a broody duck is doing the incubating for you, the broody duck guide covers what she needs and what to leave to her.