The mallard (/ˈmælɑːrd/ or /ˈmælərd/) or wild duck (Anas platyrhynchos) is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand, Australia, Peru, Brazil, Uruguay, Argentina, Chile, the Falkland Islands and South Africa. This duck belongs to the subfamily Anatinae of the waterfowl family Anatidae.
The male birds (drakes) have a glossy green head and are grey on wings and belly, while the females (hens or ducks) have mainly brown-speckled plumage. Both sexes have an area of white-bordered black speculum feathers which commonly also include iridescent blue feathers especially among males. Mallards live in wetlands, eat water plants and small animals, and are social animals preferring to congregate in groups or flocks of varying sizes. This species is the main ancestor of most breeds of domesticated ducks.
The mallard is a medium-sized waterfowl species although is often slightly heavier than most other dabbling ducks. It is 50–65 cm (20–26 in) long (of which the body makes up around two-thirds), has a wingspan of 81–98 cm (32–39 in), and weighs 0.72–1.58 kg (1.6–3.5 lb). Among standard measurements, the wing chord is 25.7 to 30.6 cm (10.1 to 12.0 in), the bill is 4.4 to 6.1 cm (1.7 to 2.4 in) and the tarsus is 4.1 to 4.8 cm (1.6 to 1.9 in).
The breeding male mallard is unmistakable, with a glossy bottle-green head and white collar which demarcates the head from the purple-tinged brown breast, grey brown wings, and a pale grey belly. The rear of the male is black, with the dark tail having white borders. The bill of the male is a yellowish orange tipped with black while that of the female is generally darker ranging from black to mottled orange. The female mallard is predominantly mottled with each individual feather showing sharp contrast from buff to very dark brown, a coloration shared by most female dabbling ducks, and has buff cheeks, eyebrow, throat and neck with a darker crown and eye-stripe.
Owing to their highly 'malleable' genetic code, Mallards can display a large amount of variation, as seen here with this female, who displays faded or 'apricot' plumage.
Both male and female mallards have distinct iridescent purple blue speculum feathers edged with white, prominent in flight or at rest, though temporarily shed during the annual summer moult. Upon hatching, the plumage colouring of the duckling is yellow on the underside and face (with streaks by the eyes) and black on the back (with some yellow spots) all the way to the top and back of the head. Its legs and bill are also black. As it nears a month in age, the duckling's plumage will start becoming drab, looking more like the female (though its plumage is more streaked) and its legs will lose their dark grey colouring. Two months after hatching, the fledgling period has ended and the duckling is now a juvenile. Between three and four months of age, the juvenile can finally begin flying as its wings are fully developed for flight (which can be confirmed by the sight of purple speculum feathers). Its bill will soon lose its dark grey colouring and its sex can finally be distinguished visually by three factors. The bill colouring is yellow in males, black and orange for females. The breast feathers are reddish-brown for males, brown for females. The centre tail feather is curled for males (called a drake feather), straight for females.
During the final period of maturity leading up to adulthood (6–10 months of age), the plumage of female juveniles remains the same while the plumage of male juveniles slowly changes to its characteristic colours. This plumage change also applies to adult mallard males when they transition in and out of their non-breeding eclipse plumage at the beginning and the end of the summer moulting period. The adulthood age for mallards is 14 months and the average life expectancy is 3 years, but they can live to twenty.
Several species of duck have brown-plumaged females which can be confused with the female mallard. The female gadwall (A. strepera) has an orange-lined bill, white belly, black and white speculum which is seen as a white square on the wings in flight, and is a smaller bird. More similar to the female mallard in North America are the American black duck (A. rubripes), which is notably darker hued in both sexes than the mallard, and the mottled duck (A. fulvigula), which is somewhat darker than the female mallard, with no white edge on the speculum and slightly different bare-part colouration.
In captivity, domestic ducks come in wild-type plumages, white, and other colours. Most of these colour variants are also known in domestic mallards not bred as livestock, but kept as pets, aviary birds, etc., where they are rare but increasing in availability.
A noisy species, the female has a deeper quack stereotypically associated with ducks. Male mallards also make a sound which is phonetically similar to that of the female, but it is a deep and raspy sound which can also sound like mek or whak. When incubating a nest, or when offspring are present, Females vocalise differently, making a call which sounds like a truncated version of the usual quack. They will also hiss if the nest or their offspring are threatened or interfered with.