The Mariana Mallard (Anas oustaleti) or Oustalet's Duck is an extinct type of duck of the genus Anas that was endemic to the Mariana Islands. Its taxonomic status is debated, and it has variously been treated as a full species, a subspecies of the Mallard or the Pacific Black Duck, or sometimes as a subspecies of the Indian Spot-billed Duck.

Taxonomy

Illustration by Allan Brooks (third bird)

The taxonomic status of the Mariana Mallard is disputed, since it resembles an intermediate of the Mallard and the Pacific Black Duck, two closely related allopatric species which frequently hybridise. Its males had two intergrading color morphs, called the "platyrhynchos" and the "superciliosa" types after the species they resembled more.^[1] It was first scientifically described by Tommaso Salvadori as full species in the genus Anas, named after its collector, the French zoologist Emile Oustalet. Salvadori suggested it was related to the Pacific Black Duck.^[2][3] It was previously known to the Chamorro people, who called it ngånga' (palao) in Chamorro, and to the Carolinian people, who called it ghereel'bwel in Carolinian.^{[citation needed]}

After Salvadori, most taxonomists, such as Dean Amadon and Ernst Mayr, considered it a subspecies of the Mallard.^[3] Yoshimaro Yamashina examined those specimens in Japanese museums in 1948, and decided that the Mariana Mallard was an example of hybrid speciation, and was descended from the Mallard and the Pacific Black Duck's Palau subspecies (Anas superciliosa pelewensis).^[3][4] However, no molecular genetic evidence is available to support this hypothesis.^{[citation needed]} Some scientists, such as Jean Delacour, have considered the Mariana Mallard a simple hybrid, so it was absent from Delacour's four-volume monograph on the ducks and from the IUCN Red List.^[3] If Yamashina's hypothesis is correct, the Mariana Mallard would have presumably evolved into near species status in only about ten thousand years.^{[citation needed]}

Neither Mariana Mallards nor their progenitor species are known from fossils on the Marianas, casting into doubt the assumption that a resident Black Duck population had been long established on the islands. However, most rock shelters and caves on the Marianas were obliterated in the 1944 Battle of Guam.^[5] A species of flightless duck is known from a prehistoric bone found on Rota in 1994; was apparently not closely related to the Mariana Mallard.^[6]

Description

Photo published in 1949

Mariana Mallards were 51–56 cm long and weighed approximately one kilogram, making them marginally smaller than mallards. Two intergrading color morphs were found in males, called the "platyrhynchos" and the "superciliosa" type after the species they resembled more.

Only the former had a distinct nuptial (breeding) plumage: the head was green as in mallard drakes, but less glossy, with some buff feathers on the sides, a dark brown eyestripe and a faint whitish ring at the base of the neck. The upper breast was dark ruddish chestnut brown with blackish-brown spots. The wing patch (speculum) and the tail was also like in mallard drakes' nuptial plumage, including curled-up central tail feathers, but the tips of the speculum feathers were buff. The underside was a mix between the vermiculated grey feathers of the mallard and the brown ones of the Pacific Black Duck. The remainder of the bird looked like a male Pacific Black Duck with lighter underwings. The bill was black at the base and olive at the tip, the feet reddish orange with darker webs and the iris brown. The eclipse plumage looked similar to a dark eclipse mallard drake.

Males of the "superciliosa" type resembled a Pacific Black Duck with a less distinctly marked head, the supercilium and cheeks being buffy and the cheek (malar) stripe hardly visible. The upper breast, flank and scapular feathers had broader buff edges, and the underwings were lighter. The speculum was usually as in the "platyrhynchos" type, i.e. mallard-like, but at least two specimens have the green speculum of the Pacific Black Duck. The bill was like that of A. superciliosa, and the iris and legs similar to the "platyrhynchos" type.

Females looked essentially like a dark mallard female with the orange of the feet and near the bill tip usually a bit more pure.

Distribution

It occurred, in recent times at least, on the islands of Guam, Saipan and Tinian. Two unidentified ducks were seen on Rota in 1945,^[1] but as no movement of A. oustaleti between Saipan and Tinian, which are just 8 kilometres (5.0 mi) apart, was recorded,^[7] these were probably vagrant migrating ducks, although Marshall (1949) suspected from circumstantial evidence that such movement did indeed take place.^[8] However, the distance between Guam and Rota is nearly 80 kilometres (50 mi), making intentional migration between these islands not likely.

Ecology

The Mariana Mallard inhabited wetlands, mostly inland but occasionally also in coastal areas. On Guam, it was most abundant in the Talofofo River valley, on Tinian on Lake Hagoi and Lake Makpo (now Makpo Swamp) before it was drained, and on Saipan on the Garpan lagoon and on and around Lake Susupe. The birds were rather reclusive, preferring sheltered habitat with plenty of wetland/water plants – fern thickets (Acrostichum aureum) and reed beds (Scirpus, Cyperus and Phragmites (australis) karka),^[9][10] where they also nested. Usually, pairs or small flocks were encountered, but in the key habitats larger groups of dozens and rarely up to 50–60 individuals could be found. Apart from possible inter-island movement, the birds were not migratory.

Feeding and reproduction are not well documented, but cannot expected to differ significantly from its immediate relatives. The Mariana Mallard fed on aquatic invertebrates, small vertebrates and plants, and although up-ending was not observed, they probably utilized it too.

Breeding was recorded from at least January to July, with a peak in June–July at the end of the dry season. One male specimen taken in October was also in breeding condition;^[8] thus, the birds may have bred nealy year-round at least on occasion. Unfortunately, the courtship behavior, which in the strongly sexually dimorphic mallard is focused more on presentation of visual cues than in the monomorphic Pacific Black Duck (although it is generally similar in both species), was never recorded. Clutches consisted of 7–12 pale grey-green oval eggs, measuring 61.6 x 38.9 mm on average.^[7] Incubation lasted around 28 days, males took no part in it and neither in caring for the ducklings. The precocial and nidifugous young fledged when about eight weeks old and became sexually mature the following year.

Extinction

The birds declined due to draining of wetlands for agriculture and construction. Hunting pressure was probably heavy, despite a ban on gun ownership under Japanese control (1914–1945), as the birds were unwary^{[verification needed]} to be trapped, and at any rate the gun ban was lifted after World War II (see also below). By the 1940s, flocks of more than a dozen birds were seldom seen. On Guam, the last sightings were in 1949 and 1967 – the latter being a single, possibly vagrant, bird – and on Tinian in 1974. As Lake Susupe offered the most plentiful and least accessible habitat, although it too suffered from pollution by sugar mill wastes, the Saipan population lingered on for a few more years. The Mariana Mallard was listed as federally endangered on June 2, 1977.^[11] In 1979, two males and a female were found on Saipan and caught; one male was later released, the last wild bird ever to be encountered. The pair was brought to Pohakuloa Training Area, Hawaii, and later to SeaWorld, San Diego, where it was attempted to have them reproduce in captivity. However, this was unsuccessful and the species became extinct with the death of the last individual in 1981. Surveys were conducted in the following years, but the species was certainly gone by then. It was removed from the USFWS Endangered Species List on February 23, 2004, due to extinction.^[12][13]

Collection of specimens for museums and private collections must have had a temporary impact during the Japanese control over the islands.^{[citation needed]} Although less than 100 specimens are on record, most were taken in the 1930s and 1940s for Japanese collectors; given the rather sedentary habits and small population size of the species, this may have jeopardized local populations to the point of extinction.^{[citation needed]} Outside Japan, 7 specimens (including the type) are in the MNHN, Paris, one in the Walter Rothschild Zoological Museum, Tring, two in the USNM, Washington D.C. and six in the AMNH, New York City.^[14] There are reports of additional specimens in Cambridge, Massachusetts and Lisbon.^[15]

References

The Mallard ( /ˈmæl.ɑːrd/ or /ˈmæl.ərd/), 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 and Australia.

The male birds have a bright green or blue 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 most domestic ducks, and can interbreed with other species of genus Anas.^[2] However, a potentially terminal side effect of this vast interbreeding capability is gradual genetic dilution, which is causing rarer species of ducks to become at risk for extinction.

Taxonomy and evolution

The Mallard was one of the many bird species originally described by Linnaeus in his 18th century work, Systema Naturae, and still bears the first binomial name given to it.^[3]

The Mallard is the ancestor of almost all of the varieties of domestic ducks. 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]

The name is derived from the Old French malart or mallart "wild drake", although its ultimate derivation is unclear. It may be related to an Old High German masculine proper name Madelhart, clues lying in the alternate English forms "maudelard" or "mawdelard".^[5]

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 is because 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.^{[citation needed]}

Mallards appear to be closer to their Indo-Pacific relatives than to their American ones judging from biogeography. Considering mtDNA D-loop sequence data,^[6] 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 west 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.^[7] 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.^[6]

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, the Greenland Mallard (A. p. conboschas).^{[citation needed]}

Description

Iridescent blue-black-white speculum feathers of male

The Mallard is 56–65 centimetres (22–26 in) long (of which the body makes up around two-thirds), has a wingspan of 81–98 centimetres (32–39 in),^[8] and weighs 0.9–1.2 kilograms (32–42 oz). The breeding male is unmistakable, with a bright bottle-green head, black rear end and a yellowish orange (can also contain some red) bill tipped with black (as opposed to the black/orange bill in females). It has a white collar which demarcates the head from the purple-tinged brown breast, grey brown wings, and a pale grey belly. The dark tail has white borders.^[9] The female Mallard is a mottled light brown, like most female dabbling ducks, and has buff cheeks, eyebrow, throat and neck with a darker crown and eye-stripe.^[9] 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 plumage coloring of the duckling is yellow on the underside and face (with streaks by the eyes) and black on the backside (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 gray coloring.^[9] Two months after hatching, the fledgling period has ended and the duckling is now a juvenile. Between three to 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 gray coloring and its sex can finally be distinguished by three factors:^{[citation needed]}

• Bill coloring: Yellow for males, Black and orange for females
• Breast Feathers: Reddish-brown for males, Brown for females
• Center Tail feather: 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 recognizable colors.^{[citation needed]} 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 molting period. The adulthood age for Mallards is 14 months and the average life expectancy is 20 years.

An American Black Duck (Anas rubripes, top left) and a male Mallard (Anas platyrhynchos, bottom right) in eclipse plumage

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.^[9]

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, and a high-pitched whistle, while the female has a deeper "quack" stereotypically associated with ducks.^[10][11]

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.^{[citation needed]}

Due to the malleability of the Mallard's genetic code, which gives it its vast interbreeding capability, mutations in the genes that decide plumage color are very common and have resulted in a wide variety of hybrids such as Brewer's duck (Mallard x Gadwall, Anas strepera).^[12]

Distribution and habitat

Female landing

The Mallard is widely distributed across the Northern Hemisphere, North America from southern and central Alaska to Mexico, the Hawaiian Islands, and across Eurasia, from Iceland and southern Greenland and parts of Morocco (North Africa) in the west, Scandinavia to the north, and to Siberia, Japan, and China in the east.^[8] 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.^[13]

The Mallard inhabits a wide range of habitat and climates, from 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 1 m (4 ft) are preferred, birds avoiding areas more than a few metres deep. They are attracted to bodies of water with aquatic vegetation.^[11]

Drake in flight

Behaviour

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.^[14] 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.^[15] Plants generally make up a larger part of the bird's diet, especially during fall migration and in the winter.^[16][17]

It 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.^[18]

Breeding

Mallard eggs and a nest

Female swimming with ducklings that are less than a week old

Mallards usually form pairs (in October and November) only until the female lays eggs at the start of nesting season which is around the beginning of spring (early March to late May), at which time she is left by the male who will join up with other males to await the molting period which begins in June. During the brief time before this, however, the males are still sexually potent and some of them will either remain on standby to sire replacement clutches (for female Mallards that have lost or abandoned their previous clutch) or forcibly mate with females of a different species that appear to be isolated or unattached.

The nesting period can be very stressful for the female; since she lays more than half her body weight in eggs and requires a lot of rest and a feeding/loafing area that is safe from predators. When seeking out a suitable nesting site, the female's preferences are areas that are well concealed, inaccessible to ground predators, or have few predators nearby. This can include urban areas that have roof gardens, enclosed courtyards, and flower boxes on window ledges more than one story up which prevents the ducklings from leaving safely without human intervention. 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 fully capable of swimming as soon as they hatch. However, Filial imprinting will compel them to instinctively stay near the mother not only for warmth and protection but also to learn about and remember their habitat as well as how and where to forage for food. When ducklings mature into flight-capable juveniles, they will learn about and remember their traditional migratory routes (unless they are born and raised in captivity). After this, the juveniles and the mother will either continue staying together (until the breeding season arrives) or they will finally part ways which can occur for two reasons.

• The mother will leave the juveniles, knowing that they can fully fend for themselves.
• The juveniles will leave the mother and set off on their own to seek out new sources of food and water, both natural and artificial.

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’ 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 the chased male died upon flying into a glass window.^[19]

Mallards are opportunistically 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.^[20]

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.^[21][22][23]

The Mallard is considered an invasive species in New Zealand. There, and elsewhere, Mallards are spreading with increasing urbanization and hybridizing with local relatives.^[24] Over time, a continuum of hybrids ranging between almost typical examples of either species will develop; the speciation process beginning to reverse itself.^[25] This has created conservation concerns for relatives of the Mallard, such as the Hawaiian Duck,^[26] the A. s. superciliosa subspecies of the Pacific Black Duck,^[27] the American Black Duck,^[28] the Mottled Duck,^[29] Meller's Duck,^[30] the Yellow-billed Duck,^[25] and the Mexican Duck,^[31] in the latter case even leading to a dispute whether these birds should be considered a species^[32] (and thus entitled to more conservation research and funding) or included in the Mallard.

The availability of Mallards, Mallard ducklings, and fertilized Mallard eggs for public sale and private ownership, either as livestock or as pets, is currently legal in the United States except for the state of Florida which has currently banned domestic ownership of Mallards. This is to prevent hybridisation with the native Mottled Duck.^[33]

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.^[23]

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.^[34] The Mariana Mallard was a resident allopatric population—in most respects a good species—apparently initially derived from Mallard-Pacific Black Duck hybrids;^[35] 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.^{[citation needed]}

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.^{[citation needed]}

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.^[36] 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.^[37] 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.^{[citation needed]}

Relationship with humans

Mallards by Carl Friedrich Deiker (1875)

Lists of miscellaneous information should be avoided. Please relocate any relevant information into appropriate sections or articles. (May 2011)

The Mallard is depicted in a marginal decoration of the 15th century English illuminated manuscript the Sherborne Missal.^[38]

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 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.^[39]

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.^[40]

Duck Head, a U.S. clothing brand, uses the image of a Mallard's head as its logo.^[41]

Mallard Drakes, or ducks that were stylized on them, are featured in Duck Hunt, a shooting game for the Nintendo Entertainment System.

See also

• Rouen Duck: A domestic duck breed that is identical to the Mallard in terms of plumage coloring.

Footnotes

References