Mallard ducks do not mate for life and only pair up during the mating season. After the female mallard has laid her eggs, the male leaves the nesting area in preparation for moulting season.
Mating mallards are typically monogamous; however, it is not uncommon for males to pursue females outside their pairing. Male mallards become very aggressive during mating season, usually because they have not found a female partner. Groups of male mallards often chase solitary females and force copulation; however, eggs laid by the female are often larger when she has mated with her chosen mate.
Mallard ducks are the forerunners of most domesticated ducks found in North America.