There are 2 recognised subspecies of Mallard:
Mention ‘duck’ and this may be the bird that comes to mind.
Perhaps most widespread and numerous of all ducks, it succeeds by its ability to adapt to areas humans use. Though principlally of the Northern Hemisphere, the Mallard has been introduced to many countries south of the Equator, including South Africa, Mauritius, Australia and New Zealand.
The wing speculum, or mirror, is present on both male and female. It is a patch of irridescent feathers appearing blue/green. Most of our domestic breeds of duck have descended from the Mallard. Many breeds still show the speculum. In some, the blue colour is masked and the speculum appears brown.
Under domestication, the process of selection is rapid. Humans have selected characteristics resulting from specific mutations and encouraged such birds to breed. This has been going on for thousands of years resulting in the wide variety of domestic breeds seen today.
Closely related to the Mallard are; the Mexican Duck A. daizi, the Mottled Duck A.fulvigula and the American Black Duck A. rubripes. The Mottled and American Black do not have the white border around the speculum.
Mallard may lay a dozen or more eggs, twice or maybe even three times a year. They prefer to nest near water and the duck generally makes her nest well covered in vegetation or in a natural hole in a tree. Incubation is 26-30 days.