Many factors contribute to the length of time it takes for a duckling to hatch. Twenty-six days is the minimum, 35 days is a max, but it depends on breed. It can be exciting to raise a brood of ducklings, but patience is your most valuable virtue. To hatch a clutch, you must be attuned to the state of the eggs throughout incubation.
Discard cracked or misshapen eggs. You can incubate eggs up to a week after they are laid, provided you store them at 60 degrees Fahrenheit. It's best to incubate within the first three days. Start incubation at 99.5 degrees Fahrenheit and 55 percent humidity.
Without a setter -- a component of some incubators that automatically turns eggs -- you'll need to turn them by hand an odd number of times each day. Since you can't turn eggs while you sleep, turning them halfway over three or five times daily helps prevent the risk of an embryo getting stuck to the same side of the egg each night. A few days prior to hatching, stop turning them. Lower the temperature to 98.5 degrees Fahrenheit and increase humidity to 94 percent.
Determine whether an egg is fertile by candling, or holding the eggs individually up to a bright flashlight in a dark room. Beginning at day 7, check for veins growing. Infertile eggs appear clear; dead eggs look cloudy. Discard those with double yolks or infected eggs that show a dark, blotchy appearance. Check again at 25 days: For common ducks, a pocket of air should occupy approximately a third of the space inside the egg.
Varying Times to Hatch
Mallards hatch early, within 26 to 27 days. Pekins and most common breeds of duck hatch at 28 days. Moscovy ducks are on the longer end, hatching after 35 days. Eggs are not laid all at the same time, so they will not hatch at the same time. Sometimes a mother begins to incubate some eggs while others in the same clutch have not been laid, so some variance in these days can be expected.
Once hatching has begun, a duckling can take several hours to emerge. Resist the urge to help them along -- unless one makes a hole but no more progress after 12 hours. Then, go ahead and gently help the duckling.
After Hatching Care
Chicks don't need food for their first 24 hours, as egg yolk has been absorbed into the duckling's abdomen. After this time, transfer ducklings to an indoor brooder box, such as a large plastic bin lined with a bath towel or old T-shirt. Affix a 60- to 75-watt bulb over one side of brooder for warmth, leaving room for ducklings to have a place to move away to if they become too warm. Feed a nonmedicated chicken mash. Provide clean water in a shallow dish they can drink from but not swim in. Introduce ducklings to water by putting their bill into the dish a few times. Protect them from young children and other household pets.