The mallard (/ˈmælɑːrd, ˈmælərd/) or wild duck (Anas platyrhynchos) is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa. It has been introduced to New Zealand, Australia, Peru, Brazil, Uruguay, Argentina, Chile, Colombia, the Falkland Islands, and South Africa. This duck belongs to the subfamily Anatinae of the waterfowl family Anatidae. Males have green heads, while the females (hens or ducks) have mainly brown-speckled plumage. Both sexes have an area of white-bordered black or iridescent purple or blue feathers called a speculum on their wings; males especially tend to have blue speculum feathers. The mallard is 50–65 cm (20–26 in) long, of which the body makes up around two-thirds the length. The wingspan is 81–98 cm (32–39 in) and the bill is 4.4 to 6.1 cm (1.7 to 2.4 in) long. It is often slightly heavier than most other dabbling ducks, weighing 0.7–1.6 kg (1.5–3.5 lb). Mallards live in wetlands, eat water plants and small animals, and are social animals preferring to congregate in groups or flocks of varying sizes.
The female lays 8 to 13 creamy white to greenish-buff spotless eggs, on alternate days. Incubation takes 27 to 28 days and fledging takes 50 to 60 days. The ducklings are precocial and fully capable of swimming as soon as they hatch.
The mallard is considered to be a species of least concern by the International Union for Conservation of Nature (IUCN). Unlike many waterfowl, mallards are considered an invasive species in some regions. It is a very adaptable species, being able to live and even thrive in urban areas which may have supported more localised, sensitive species of waterfowl before development. The non-migratory mallard interbreeds with indigenous wild ducks of closely related species through genetic pollution by producing fertile offspring. Complete hybridisation of various species of wild duck gene pools could result in the extinction of many indigenous waterfowl. This species is the main ancestor of most breeds of domestic duck, and its naturally evolved wild gene pool has been genetically polluted by the domestic and feral mallard populations.
The mallard is widely distributed across the Northern and Southern Hemispheres; in North America its range extends from southern and central Alaska to Mexico, the Hawaiian Islands, across the Palearctic, from Iceland and southern Greenland and parts of Morocco (North Africa) in the west, Scandinavia and Britain to the north, and to Siberia, Japan, and South Korea. Also in the east, it ranges to south-eastern and south-western Australia and New Zealand in the Southern hemisphere.: 505 It is strongly migratory in the northern parts of its breeding range, and winters farther south. For example, in North America, it winters south to the southern United States and northern Mexico, but also regularly strays into Central America and the Caribbean between September and May. A drake later named "Trevor" attracted media attention in 2018 when it turned up on the island of Niue, an atypical location for mallards.
The mallard inhabits a wide range of habitats and climates, from the Arctic tundra to subtropical regions. It is found in both fresh- and salt-water wetlands, including parks, small ponds, rivers, lakes and estuaries, as well as shallow inlets and open sea within sight of the coastline. Water depths of less than 0.9 metres (3.0 ft) are preferred, with birds avoiding areas more than a few metres deep. They are attracted to bodies of water with aquatic vegetation.
The mallard is omnivorous and very flexible in its choice of food. Its diet may vary based on several factors, including the stage of the breeding cycle, short-term variations in available food, nutrient availability, and interspecific and intraspecific competition. The majority of the mallard's diet seems to be made up of gastropods, insects (including beetles, flies, lepidopterans, dragonflies, and caddisflies), crustaceans, other arthropods, worms, many varieties of seeds and plant matter, and roots and tubers. During the breeding season, male birds were recorded to have eaten 37.6% animal matter and 62.4% plant matter, most notably the grass Echinochloa crus-galli, and nonlaying females ate 37.0% animal matter and 63.0% plant matter, while laying females ate 71.9% animal matter and only 28.1% plant matter. Plants generally make up the larger part of a bird's diet, especially during autumn migration and in the winter.
The mallard usually feeds by dabbling for plant food or grazing; there are reports of it eating frogs. However, in 2017 a flock of mallards in Romania were observed hunting small migratory birds, including grey wagtails and black redstarts, the first documented occasion they had been seen attacking and consuming large vertebrates. It usually nests on a river bank, but not always near water. It is highly gregarious outside of the breeding season and forms large flocks, which are known as "sordes".
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