They were considered quite desirable for roast duck.
There are two varieties. One has black feathers and a dark black head; there is also a blue variety. Both have a long bill, one white feather at the end of each wing, and a white bib.
The male will weigh up to 6.6 pounds (3 kg); females up to 5.5 pounds (2.5 kg.)
The ducks like to forage for food, particularly slugs and snails.
The females start laying eggs by October. They’ll lay 80 to 100 eggs a year. The eggs weigh about 70g, and have a bluish-green shell.
The eggs will start hatching by November. Duclair ducklings are considered table-ready for table at 8 weeks old, so this allows them to be sold from January through to spring (Twelfth Night through to Easter) as duckling.
Duclair is a variety of Rouen duck that originated in and near the town of Duclair, Normandy. Breeding standards for them were established on 23 November 1923.
Sometimes three different people were involved in the “Duclair Duck business.”
The first would be the seller of the eggs. Farm women would buy the eggs when they had a broody chicken or turkey ready for the job of sitting on the eggs. After five days, the women would examine the eggs by candle light held behind them to check for activity. If nothing was happening, they were unfertilized eggs and could be used as regular eggs in cooking, or returned to the seller. The farm wives would then raise the newly-hatched ducklings for a week or two, then sell the ducklings onto people who then specialized in the art of fattening them for market. They were fed chopped egg mixed with nettles, barley meal and milk formed into pellets and put down their throats by finger, as well as worms collected for them.
The Duclair Ducks. New York Times. 23 November 1879.