Set up a routine for the breeding season. Number all the nest boxes you have and enter this information into a log. Inspect the boxes at least once a week to check if there are any eggs, being careful not to disturb the female duck if she is in the box. Identify if possible the duck and count the eggs and then enter the species and the number of eggs against the nest box number in your log book.
What normally happens is that she will start laying an egg a day (on average). Once she finished laying her clutch she will start sitting on the eggs on a 24/7 basis. This is the time that you should start counting the days so you can be ready for the day the ducklings hatch. A rule of thumb for most ducks is 28 to30 days BUT it varies so better make sure of the exact amount of days for each species. In this time she will only get off for short periods (not longer than 15 to 20 and maximum 30 minutes depending on the temperature outside) to eat, drink, swim and preen herself. It is quite normal for the eggs to cool down in this period but she makes sure they do not get completely cold by pulling a blanket of down feathers over the eggs before she leaves the nest. It is important for her to be able to swim because when she goes back on the eggs she takes much needed moisture with her to keep the humidity just right for the eggs to develop.
You can help the process along by spraying the eggs with luke warm water from about 4 days before they hatch. This will help the humidity in the box to rise considerably and thus soften the eggs so that the ducklings can break through. PLEASE NOTE that this should only be done when you see the mother off the eggs. Do not disturb her unnecessarily!
There are two options available to you; the first is to let the eggs hatch naturally or secondly, if you have an incubator, is to take the eggs out of the nest box about a week before hatching as then the mother has taken them through the most risky period.. The advantage of doing this is that the female is likely to lay a second batch and the eggs are kept safe from predators (especially rats).
When the eggs start hatching you will probably see and hear them in the nest box opening. Resist the temptation to pick them up and handle them. They normally spend the first day under the mother so that the oil on her feathers rubs off on them so that by the time they leave the nest they can go directly into the water. Don’t be alarmed when you see them on the water the next day. They will not drown. They will get a bit wet and it is most important that they can get to the mother easily so she can keep them warm. When the ducklings hatch they are literally skin and bone and about one breath away from death. It is only by day 4 to 6 that you know that the ones that have survived it thus far have a greater chance of making it further.
Once you see them off the nest make sure that you put out some starter crumble in a clean flat bowl and some clean water in a drinker next to it. Some ducklings (in fact most wild ducklings) like the Mandarins and Carolina ducklings do not know how to eat. They need their mother with them so she can show them how. She will start pecking at the food and they follow. Once your ducklings make it through the first 4 to 6 days and especially if you see them feeding you know they should survive!
If for some reason you had to take the ducklings away from the mother it is good to get a baby chicken because he will start pecking at the food and your ducklings will follow.
This also applies to the duckling that are bred in the incubator and placed in raising boxes.