Mallard

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For other uses, see Mallard (disambiguation).

"Wild Duck" redirects here. For the play by Henrik Ibsen, see The Wild Duck.

Mallard
Male (right) and female (left) Mallard
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Subfamily:	Anatinae
Genus:	Anas
Species:	A. platyrhynchos
Binomial name
Anas platyrhynchos Linnaeus, 1758
Subspecies
See Mexican Duck, Anas and below A. p. domesticus Domesticated duck   (Linnaeus, 1758)
Synonyms
Anas boschas

The Mallard, or Wild duck (Anas platyrhynchos^[1]), is a dabbling duck which breeds throughout the temperate and sub-tropical Americas, Europe, Asia, and North Africa, and has become introduced to New Zealand and Australia.
The male birds have a bright green head, while the female's is light brown. The Mallard lives in wetlands, eats water plants, and is gregarious. It is also migratory. The Mallard is the ancestor of all domestic ducks, and can interbreed with other species of genus Anas.^[2] This interbreeding is causing rarer species of ducks to become genetically diluted.

Contents [hide] 1 Taxonomy and evolution 2 Description 3 Habitat and distribution 4 Behaviour 4.1 Feeding 4.2 Breeding 5 Conservation 6 Relationship with humans 7 Footnotes 8 References 9 External links

[edit] Taxonomy and evolution

Mallard eggs and a nest.

The Mallard was one of the many species originally described by Linnaeus in his 18th century work, Systema Naturae, and still bears the first binomial name given it.^[3]
The Mallard is the ancestor of almost all of the varieties of domestic ducks. Domestic ducks belong to the subfamily Anatinae of the waterfowl family Anatidae. The wild Mallard and Muscovy duck (Cairina moschata) are believed to be the ancestors of all domestic ducks.^[4]
Mallards frequently interbreed with their closest relatives in the genus Anas, such as the American Black Duck, and also with species more distantly related, for example the Northern Pintail, leading to various hybrids that may be fully fertile. This is quite unusual among different species, and apparently has its reasons in the fact that the Mallard evolved very rapidly and not too long ago, during the Late Pleistocene only. The distinct lineages of this radiation are usually kept separate due to non-overlapping ranges and behavioural cues, but are still not fully genetically incompatible. Mallards and their domesticated conspecifics are, of course, also fully interfertile.

Iridescent blue-black-white speculum feathers of male

Mallards appear to be closer to their Indo-Pacific relatives than to their American ones judging from biogeography. Considering mtDNA D-loop sequence data,^[5] they may have evolved more probably than not in the general area of Siberia; Mallard bones rather abruptly appear in food remains of ancient humans and other deposits of fossil bones in Europe, without a good candidate for a local predecessor species^{[citation needed]}. The large ice age paleosubspecies which made up at least the European and W Asian populations during the Pleistocene has been named Anas platyrhynchos palaeoboschas^{[citation needed]}.
Haplotypes typical of American Mallard relatives and Spotbills can be found in Mallards around the Bering Sea.^[6] The Aleutian Islands turned out to hold a population of Mallards that appear to be evolving towards a subspecies as gene flow with other populations is very limited.^[5]
The size of the Mallard varies clinally, and birds from Greenland, although larger than birds further south, have smaller bills and are stockier. It is sometimes separated as subspecies Greenland Mallard (A. p. conboschas).

[edit] Description

The Mallard is 56–65 centimetres (22–26 in) long, has a wingspan of 81–98 centimetres (32–39 in), and weighs 0.9–1.2 kilograms (32–42 oz). The breeding male is unmistakable, with a bright green head, black rear end and a yellowish orange (can also contain some red) bill tipped with black (as opposed to the dark brown bill in females), and is also nature's most feared duck. The female Mallard is light brown, like most female dabbling ducks. However, both the female and male Mallards have distinct purple speculum edged with white, prominent in flight or at rest (though temporarily shed during the annual summer moult). Upon hatching, the duckling's plumage is yellow on the underside, black on the backside with some yellow spots, and yellow on the face with black on the top and back of the head with streaks by the eyes. It's legs and bill are also black but they'll gradually change color with age. In non-breeding (eclipse) plumage the drake becomes drab, looking more like the female, but still distinguishable by its yellow bill and reddish breast.
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 male has a nasal call, the female has a "quack" stereotypically associated with ducks.^[7]
The Mallard is a rare example of both Allen's Rule and Bergmann's Rule in birds. Bergmann's Rule, which states that polar forms tend to be larger than related ones from warmer climates, has numerous examples in birds. Allen's Rule says that appendages like ears tend to be smaller in polar forms to minimize heat loss, and larger in tropical and desert equivalents to facilitate heat diffusion, and that the polar taxa are stockier overall. Examples of this rule in birds are rare, as they lack external ears. However, the bill of ducks is very well supplied with blood vessels and is vulnerable to cold.

[edit] Habitat and distribution

Drake in flight

The Mallard inhabits most wetlands, including parks, small ponds and rivers, and usually feeds by dabbling for plant food or grazing; there are reports of it eating frogs. It usually nests on a river bank, but not always near water. It is highly gregarious outside of the breeding season and will form large flocks, which are known as a sord.^[8]

Female landing

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 Mexico, but also regularly strays into Central America and the Caribbean between September and May.^[9]

[edit] Behaviour

[edit] Feeding

The Mallard is omnivorous and very flexible in its food choice. Its diet may vary based on several factors, including the stage of the breeding cycle, short term variations in available food, nutrient availability, and inter- and intraspecific competition.^[10] The majority of the Mallard's diet seems to be made up of gastropods, invertebrates (including beetles, flies, lepidopterans, dragonflies, and caddisflies), crustaceans, 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 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.^[11] Plants generally make up a larger part of the bird's diet, especially during fall migration and in the winter.^[12][13]

[edit] Breeding

Mallards usually form pairs only until the female lays eggs, at which time she is left by the male. The clutch is 8–13 eggs, which are incubated for 27–28 days to hatching with 50–60 days to fledgling. The ducklings are precocial, and can swim and feed themselves on insects as soon as they hatch, although they stay near the female for protection.
When they pair off with mating partners, often one or several drakes will end up "left out". This group will sometimes target an isolated female duck, even when she's of a different species, and proceed to chase and peck at her until she weakens, at which point each male will take turns copulating with the female. Lebret (1961) calls this behaviour 'Attempted Rape Flight' (ARF) and Cramp & Simmons (1977) speak of 'rape-intent flights'. Male Mallards will also occasionally chase other male ducks of a different species, and even each other, in the same way. In one documented case of 'homosexual necrophilia', a male Mallard copulated with another male he was chasing after said male had been killed upon flying into a glass window.^[14]
Mallards are opportunisticly targeted by brood parasites, occasionally having eggs laid in their nests by Redheads, Ruddy Ducks, Lesser Scaup, Gadwalls, Northern Shovelers , Northern Pintails, Cinnamon Teal, Common Goldeneyes and other Mallards. These eggs are generally accepted when they resemble the eggs of the host Mallard, although the hen may attempt to eject them or even abandon the nest if parasitism occurs during egg laying.^[15]

[edit] Conservation

The last male Mariana Mallard.

The release of feral Mallards in areas where they are not native sometimes creates problems through interbreeding with indigenous waterfowl. These non-migratory Mallards interbreed with indigenous wild ducks from local populations of closely related species through genetic pollution by producing fertile offspring. Complete hybridization of various species of wild ducks gene pools could result in the extinction of many indigenous waterfowl. The wild Mallard itself is the ancestor of most domestic ducks and its naturally evolved wild gene pool gets genetically polluted in turn by the domesticated and feral populations.^[16][17][18]
The Mallard is considered an invasive species in New Zealand. There, and elsewhere, Mallards are spreading with increasing urbanization and hybridizing with local relatives.^[19] Over time, a continuum of hybrids ranging between almost typical examples of either species will develop; the speciation process beginning to reverse itself.^[20] This has created conservation concerns for relatives of the Mallard, such as the Hawaiian Duck,^[21] the A. s. superciliosa subspecies of the Pacific Black Duck,^[22] the American Black Duck,^[23] the Mottled Duck,^[24] Meller's Duck,^[25] the Yellow-billed Duck,^[20] and the Mexican Duck,^[26] in the latter case even leading to a dispute whether these birds should be considered a species^[27] (and thus entitled to more conservation research and funding) or included in the Mallard.
In the state of Florida, domestic ownership of Mallards is currently banned. This is to prevent hybridisation with the native Mottled Duck.^[28]
Mallards are also causing severe "genetic pollution" of South Africa's biodiversity by breeding with endemic ducks, although the Agreement on the Conservation of African-Eurasian Migratory Waterbirds applies to the Mallard. The hybrids of Mallard and the Yellow-billed Duck are fertile and can produce more hybrid offspring. If this continues, only hybrids will occur and in the long term this will result in the extinction of various indigenous waterfowl. The Mallard duck can cross breed with 63 other species and is posing a severe threat to the genetic integrity of indigenous waterfowl. Mallards and their hybrids compete with indigenous birds for resources such as food, nest sites and roosting sites.^[18]

Several drakes swim in a pond

The Chinese Spotbill is currently introgressing into the Mallard populations of the Primorsky Krai, possibly due to habitat changes from global warming.^[29] The Mariana Mallard was a resident allopatric population—in most respects a good species—apparently initially derived from Mallard-Pacific Black Duck hybrids;^[30] unfortunately, it became extinct in the 1980s. In addition, feral domestic ducks interbreeding with Mallards have led to a size increase—especially in drakes—in most Mallards in urban areas. Rape flights between normal-sized females and such stronger males are liable to end with the female being drowned by the males' combined weight.

Female with ducklings that are less than a week old

Ducklings following mother in Boston Harbor, USA

The Laysan Duck is an insular relative of the Mallard with a very small and fluctuating population. Mallards sometimes arrive on its island home during migration, and can be expected to occasionally have remained and hybridized with Laysan Ducks as long as these species exist. But these hybrids are less well adapted to the peculiar ecological conditions of Laysan Island than the local ducks, and thus have lower fitness, and furthermore, there were—apart from a brief time in the early 20th century when the Laysan Duck was almost extinct—always much more Laysan Ducks than stray Mallards. Thus, in this case, the hybrid lineages would rapidly fail.
In the cases mentioned above, however, ecological changes and hunting have led to a decline of local species; for example, the New Zealand Grey Duck population declined drastically due to overhunting in the mid-20th century.^[31] In the Hawaiian Duck, it seems that hybrid offspring are less well-adapted to native habitat and that utilizing them in reintroduction projects makes these less than successful.^[32] In conclusion, the crucial point underlying the problems of Mallards "hybridizing away" relatives is far less a consequence of Mallards spreading, but of local ducks declining; allopatric speciation and isolating behaviour have produced today's diversity of Mallard-like ducks despite the fact that in most if not all of these populations, hybridization must have occurred to some extent.

[edit] Relationship with humans

The Mallard is depicted in a marginal decoration of the 15th century English illuminated manuscript the Sherborne Missal.^[33]
Since 1933, the Peabody Hotel in Downtown Memphis, Tennessee has maintained a long tradition of keeping one Mallard drake and four Mallard hens, called The Peabody Ducks, as a popular hotel attraction and as guests of honor. The tradition initially began on December 3 with keeping three English Call ducks in the Lobby Fountain, but it was changed over to five Mallards (one drake and four hens) after much popular feedback from the hotel guests. The Mallards are provided by a local farmer and friend of the Peabody Hotel and are rotated out and returned to the farm for a new team of Mallards every three months. This tradition has also been maintained and observed at the other Peabody Hotels in Little Rock, Arkansas and Orlando, Florida.^[34]
The children's picture book Make Way for Ducklings, published in 1941 and winner of the 1942 Caldecott Medal for its illustrations, is the story of a pair of Mallards who decide to raise their family on an island in the lagoon in Boston Public Garden in Massachusetts.^[35]
Duck Head, a U.S. clothing brand, uses the image of a Mallard's head as its logo.^[36]
Mallard Drakes, or ducks that were stylized on them, are featured in Duck Hunt, a classic shooting game for the Nintendo Entertainment System.