Mallard, Anas platyrhynchos

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Taxonomy

Taxonomic lineage

cellular organisms - Eukaryota - Fungi/Metazoa group - Metazoa - Eumetazoa - Bilateria - Coelomata - Deuterostomia - Chordata - Craniata - Vertebrata - Gnathostomata - Teleostomi - Euteleostomi - Sarcopterygii - Tetrapoda - Amniota - Sauropsida - Sauria - Archosauria - Dinosauria - Saurischia - Theropoda - Coelurosauria - Aves - Neognathae - Anseriformes - Anatidae - Anas - Anas platyrhynchos

Order Anseriformes

The order consists of 3 families. Family Anatidae is most diverse and rich in genera and includes species commonly known as waterfowl (geese, swans, ducks, eiders, and teals). The other families are Anseranatidae (magpie geese) and Anhimidae (screamers).

Genus Anas

Genus Anas contains about 50 species of ducks. Ducks are characterized by compact bodies streamlined for swimming with thick subcutaneous fat layer for preserving body heat when immersed in water. Legs are short and set far back on their body, which makes them clumsy on land but gives them more power when swimming. Wide, strongly webbed feet are designed for efficient paddling on the surface of the water as well as diving. Duck have broad and flattened bills usually with a hard nail at the end and slight serrations or a comb-like structure on the sides of the bill. A duck's plumage is dense and thoroughly insulates the body from water and provides superb temperature control in the water. Ducks are usually sexually dimorphic with males characterized by vibrant plumage colors and females being much more subdued with neutral colors and mottled patterns for better camouflage.

Anas platyrhynchos

Mallards frequently interbreed with their species in the genus Anas, such as American Black Duck (Anas rubripes), Florida Duck (A. fulvigula) and others producing hybrids that may be fully fertile with variations in plumage color as well as behavioral characteristics.

According to recent genetic studies, mallard ducks made a major contribution in shaping various breeds of domestic ducks. China is particularly rich in duck genetic resources. The results of 667 bp control region of mitochondrial DNA indicated that the Chinese domestic ducks mainly derived from mallard (A. platyrhynchos) and few derived from spot-billed duck (A. zonorhyncha).

Brief facts

• Description

  The Mallard Duck is approximately 60 cm (2 feet) long with a wing span of 82-95 cm (32-37 inches). Mallards are sexually dimorphic. Males (drakes) have breeding (alternate) plumage and basic (eclipse) plumage. Male breeding plumage is characterized by iridescent dark green head, narrow white neck ring and chestnut-brown breast. Back and wings are brownish gray. Underparts are light grayish. Tail is white on outside with two distinct black feathers in the centre that curve back. Bill is yellow to greenish, with black nail at tip. The eclipse plumage is similar to the females, but it maintains its yellow bill and chestnut colored breast. Females (hens) have plumage that is similar to basic plumage of males: pale brownish face, dark line through eye, mottled brown body and wings. Juveniles are similar to females. Often, a distinguishing speculum (a bright blue rectangular spot of color) can be seen on wings of drakes and hens.

• Distribution

  The Mallard duck is the best-known species of surface-feeding or dabbling duck in the northern hemisphere. The species is distributed mainly in wetlands throughout North America, Europe, and Asia and has been introduced to other parts of the world.

• Ecology and habitat

  Mallards prefer wetlands with large amounts of floating, emergent and submerged vegetation. Mallards are omnivores. They eat various seeds including grass and tree seeds. They filter-feed on the surface of the water or dabble (dabbling duck) searching for food in the tipped-up position with its tail held vertically out of the water. Quick horizontal turns of the bill result in a characteristic to these ducks vibrations of the head which stir up aquatic invertebrates and small vertebrates (insect larvae, tadpoles, mollusks, fish eggs, etc.) on which mallards feed and push aside rough vegetation.

• Migrations

  During winter, most mallard ducks migrate to parts of the central and southern United States where lakes and ponds stay completely or partially ice-free. Mallards may also over winter in southern Ontario and southern British Columbia, and as far south as northern Mexico. The fall migration usually begins in late September or October. Some mallards, however, may stay through the winter in areas where food and shelter are abundant; these mallards form resident populations.

• Predators, diseases and mortality

  Nests are subjected to predation by herring gulls (Larus argentatus), fish crows (Corvus ossifragus) and common crows (C. brachyrhynchos). In addition to avian predators, nests also can be destroyed by raccoons (Procyon lotor), foxes (Vulpes vulpes), and rats (Rattus spp.). Ducklings can fall prey to gulls, crows, owls, weasels, and foxes. Snapping turtles and black-crowned night heron are also suspected to be responsible to the loss of ducklings.
  Adult mortality is often attributed to diseases such as viral enteritis and avian influenza (influenza virus type A) and poisoning including outbreaks of botulism due to growth of Clostridium bacteria in stagnant water.
  Ducks of all ages can be killed by severe weather and by accidents. Ducks are one of most popular game birds and are actively hunted.
  Although mallard ducks have been known to live as long as sixteen years of age in captivity, most wild ducks survive for 2-3 years.

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Developmental stages (life cycle)

• Embryo
  • Before laying The fertilized egg is located in the hen's oviduct. Fertilization, cleavage and blastodisc formation occur as well as preparation of egg to laying (shell formation).
  • After laying Embryo development in the egg takes 28 days at 99.5°F (37.5°C) and 55-75% humidity.
    • Blastodisc
      enlargement Day 1-2 after laying. Blastodisc grows to 10-15 mm in diameter. Blood not yet present.enlarged (5-8 mm in
    • Formation of
      blood vessels Day 3-4. By 4^th day, blastodisc (22-30 mm in diameter) divided into small central embryonic area, reddish vitelline vessels form cross with the embryo.
    • Head fold &
      tail fold Day 6. Blastodisc encompasses half the yolk, distinct head fold and tail fold, eye pigmentation, choroid fissure is obvious, limb are noticeable.
    • Formation of bird
      • Day 8 Limb buds and neck elongated, eye well developed, beginning of bill noticeable, brain visible.
      • Day 10 Head and body almost equal in proportion, webs on feet observable, egg tooth, development of eyelid, colorless feather germs may be present on the back.
      • Day 13 Limbs structurally similar to adults, colorless feather germs over entire body except limbs.
      • Day 15 Dark feather germs on the lower back and flanks, feathers on tail and back, feather buds are very obvious on head and body and beginning to appear on wings, eyelid becoming opaque, development of toe nails.
      • Day 17-20 Embryo grows. Down developing on all tracts. Eyelid not completely closed, feet translucent fleshy colored, egg tooth hard and whitish (day 19). Irregular, low and moderate amplitude jerky movements of embryo parts which do not appear to be coordinated with each other (type I motility) and vigorous and rapid, abrupt and jerky movements or tremors with higher amplitude, usually involving the entire body (type II motility).
    • Pre-hatching
      • Pre-tuck 21 day. Refers to a stage just prior to the initiation of tucking. The embryo is oriented lengthwise in the shell with the legs towards the small end, the neck is arched around under the air-space, and the bill and anterior head are buried in the yolk-sac between the legs.
      • Tucking 21-22 day. Vigorous wriggle of the whole body, involving head movements, a lifting of the trunk in the shoulder region and often coordinated flapping of both wings (type II motility). These movements lift the head out of the yolk and eventually results in the right wing covering the right side of the head.
      • Draping 23 day. Once the embryo has tucked its head under the right wing it shifts position within the egg so that the bill now pushes up into the membrane separating it from the air-space. This results in the membranes being draped down over the bill.
      • Membrane
        penetration 24 day. Within a few hours after the bill is draped it penetrates through the membranes and extends into the air-space close to the shell. At this time, embryos start vocalizing providing auditory stimulation to each other and to themselves.
      • Pipping 24-25 day. The time between membrane penetration and pipping is variable but pipping usually occurs from 10 to 24 hr after membrane penetration. The movements involved in making this first crack are termed pipping. When the egg is oriented on its side parallel to the horizontal plane, pipping occurs in the upper part of the shell at the blunt end.
      • Climax 26-28 day. Beginning of hatching. Twelve to 24 hr (mean = 15.5 hr) after pipping the embryo begins a sequence of movements which serve to rotate it counterclockwise within the shell and at the same time further crack the shell about two-thirds of the way round.
      • Emergence Although the time from climax to emergence may take up to 3 hr, it usually occurs within 30 to 45 min. After rotating about two-thirds of the way around the shell during climax the embryo then pushes the shell cap off and emerges from the egg.
• After hatching
  • Nestling The ducklings are precocial, which means they can swim and feed themselves right after hatching. They stay in the nest, however, until mother duck leads her brood out of the nest to the nearby water. The age of the ducklings at the time of the exodus varies between 15 and 25.5 hours after hatching.
  • Juvenile Ducklings stay close to their mother for protection until they fledge at age 50 to 60 days.
  • Mature adult Birds with mature reproductive organs, capable of breeding around or less 1 year of age (in next spring after hatching). Male may not start breeding until the second spring of his life. After breeding season mallards molt in late spring or early summer. The males molt after breeding, females molt after raising their brood.
    • Pairing & rape Most mallards form seasonally monogamous pair bonds during spring migration but sometimes pairing occurs during autumn migration, on wintering areas. Females are selective in choosing a mate, likely evaluating male attributes such as age, body size, dominance rank, experience, and plumage quality. Paired males must defend their mates from the ever-increasing pool of unpaired or loosely paired males. It may benefit the female to maintain the pair bond as long as possible for protection through the breeding season and for re-nesting attempts. However, sometime during the latter portion of the breeding season, the male's costs of maintaining the pair bond presumably outweigh the benefits, and the bond is terminated: males gradually decrease the amount of time spent in the presence of their mates especially after they become infertile at the end of the season. Long-term pair bonds in Mallards are very rare but instances of continuing relationship for more than one season are documented. In addition to copulating with their own mates, male mallards pursue other females, forcibly restraining them, mounting, and in many cases successfully achieve intromission. This phenomenon is referred as rape. Rape attempts are readily distinguishable by: (1) active resistance on the part of the female; and (2) absence of pre-copulatory displays characteristic of normal, non-forced pair bond copulations. After an apparently successful copulation, the male usually departs quickly, sometimes in response to active defense by the female's mate, and often without performing post-copulatory displays. This behavior The most plausible explanation for this behavior is that it is a secondary reproductive strategy of paired males: while their mates are laying or incubating, these males attempt to fertilize more eggs. Studies of captive ducks have shown that females can store viable sperm for up to 17 days, with full viability maintained for the first 8 days. In addition, in captive Mallards sperm from different males compete, and eggs can be fertilized by sperm delivered during forced copulation. Another study found that multiple parentage occurred in at least 17-25% of the Mallard clutches. This is likely result of forced copulations because (1) females actively avoid extra-pair copulations; (2) there was no evidence for intraspecies for brood parasitism in studied mallards.
    • Nesting Paired drake selects a nesting range, which he will defend against other pairs, whereas the hen selects a specific nest site. After she lays her eight to twelve eggs (usually cream-colored to grayish to greenish without markings) and begins incubating them, she plucks down from her breast to add to the nest lining.
      • Nest building Usually, hen digs in moist soil to form a shallow depression, lining it with soft reeds and grasses and camouflaging it with surrounding vegetation. The nest is usually concealed in tall grass or reeds.
      • Egg laying Mallards can lay up to 14 eggs at approx. rate 1 egg/day. Ducks that nest in urban settings produce larger clutches (average 11.7 eggs) than wild ducks (average 9.5 eggs). Eggs' length is about 5.5-5.6 cm; weight is 50-60 g. Ducks can lay up to 3 clutches in one season after loss of previous clutches.
      • Incubation After hen laid all her eggs, she start incubating them. She plucks down from her breast to add to the nest lining. The males abandon incubating females, move to secluded areas and start molting. The molting of their wing feathers leaves them temporarily flightless. They are no longer displaying their courtship plumage, but a drab "eclipse" plumage is similar to that of a female. It provides better camouflage against predators while their wing feathers grow back. The entire process takes 2 to 3 weeks. The hens go through a similar molt once their ducklings have fledged. Molting
      • Hatching &
        raising offspring Beginning around the time that the embryos move their heads into the air space, the hen starts uttering maternal calls. After all eggs hatched, hen keeps ducklings in the nest for several more hours after which she leads her brood to nearby water. For several weeks ducklings follow the hen. She protects them from adverse weather, leads them to feeding sites or away from danger, herds them so that they do not disperse and distracts predators if necessary. Because the feathers of a young ducklings are not sufficiently developed to properly protect them for extended periods in the water, mother duck monitors the time they spend in the water as well as provides extra preen oil in addition to what is produced by the ducklings for better insulation.

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Mallard "language"

Intraspecies communications is a fascinating subject of ethological studies. Since ancient times humans observe waterfowl behavior and use the knowledge in hunting strategies. There is a wealth of descriptive information on both vocal and visual displays of waterfowl. Being a popular game as well as a direct ancestor of almost all strains of domestic ducks, the Mallard is one of the most studied waterfowl species. Mallard's "language" comprises various ritualized combinations of vocalization and physical displays, which are inherited from generation to generation.

The Mallard's repertoire is briefly outlined below.

Female (hen)

• Inciting Has been described as a loud, tremulous queg geg geg geg associated with sideward head movements. Occurs during pair formation when showing preference for certain drake or greeting to returning mate; also, after hostile encounters.
• Decrescendo "Hail call". One of the most familiar vocalizations described as qua Quack quack quack quack quack associated with bird's stretching her neck upward while sitting or swimming. Occurs most frequently around sunrise or sunset. Uttered year around usually by unpaired birds as a response to another conspecific. Presumably indicates location to conspecifics and availability to nearby males. Hunters often imitate the sound to attract passing birds to decoys.
• Spring persistent
  quacking Single quacks or a group of quacks in irregular or regular patterns. Associated with the beginning of the breeding period (April-May). Characteristic to paired females that are about to lay eggs.
• Repulsion Series of harsh notes rendered as gaeck, associated with neck lowered into shoulders, widely opened bill, fanned tail and ruffled feathers. Occurs in incubating and brooding female or in female who lost her clutch and requires fertilization to re-nest. Possibly repels hostile conspecifics and/or attracts males.
• Preflight call A series of short, sharp notes ranging from whimpering sounds made with closed bill to a harsh gack made with open bill. Associated with movements that are characteristic of birds preparing to take wing. Heard more frequently in fall. Indicates readiness to fly and synchronizes simultaneous take-off.
• Calls of
  broody female "Maternal" calls. A series of low frequency, low amplitude notes uttered in irregular intervals. Begin to occur before hatching and during raising of the young. Provides auditory imprinting and maintains contact between female and her brood.
• Alarm call As single quaaaaack at sight of a flying predator or as "distraction display" given to a brood in a series of short nasal notes that resemble the Repulsion call but not as harsh.
• Single quacks Random quacks. Occur year around as an acknowledgment of conspecifics in a variety of situations.

Male (drake)

• Slow Raehb Rasping sound given as a slow monosyllabic, drawn-out raehb. Occur all year round, less frequent during molt. Given in a variety of social situations amidst of conspecifics or as a mate-to-mate communication.
• Rabrab All rab sounds made by the drake, other than the drawn-out Slow raehb. Given in many different situations but is generally associated with aggressiveness between males that often is accompanied by bill-up displays sometimes intermixed with ritualized drinking and preening. Indicates nervousness and disturbance.
• Courtship sounds Produced only in presence of female. Stereotyped or ritualized modifications of normal body shaking accompanied by a specific vocalization.
  • Grunt-whistle Down-up display. Produced when the male lowers his bill to the water surface and then arches his body upward flicking the bill sideways that produces a spray of water droplets. While the head is being brought backward and the breast is at its deepest point in the water, a pure tone whistle is emitted during air intake; the grunting sound results from compressed air being released.
  • Whistle Head-up-tail-up display. Produced when the male raises his tail almost vertically, folded wings are lifted and back of the neck touches the shoulders, body is parallel to the water surface. The posturing is performed at profile view to a courted female after which the male reorients his body toward the female and nod-swims quickly past her.
  • Post-copulatory
    whistle & grunting< Given after successful copulation including successful rape. In most instances, the male utters the whistle while still grasping the female's crown feathers with his bill. After the male dismounted the female, he nod-swims silently around female.

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Photo gallery

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Video

Female mallard with duckling (8/7/11, Maryland, United States)

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References

• Li HF, Zhu WQ, Song WT, Shu JT, Han W, Chen KW. Origin and domestication history of Peking ducks deltermined through microsatellite and mitochondrial marker analysis. Mol Phylogenet Evol. 2010 Nov;57(2):634-40. Epub 2010 Jul 30.
• Qu L, Liu W, Yang F, Hou Z, Zheng J, Xu G, Yang N. Origin and domestication history of Peking ducks deltermined through microsatellite and mitochondrial marker analysis. Sci China C Life Sci. 2009 Nov;52(11):1030-5.
• Goode A. Mallard Duck. Anas platyrhynchos. (.pdf)
• allaboutbirds.org: Mallard Duck
• Rogers, D. 2001. "Anas platyrhynchos" (On-line), Animal Diversity Web. Accessed September 04, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Anas_platyrhynchos.html.
• Ramsay AO. Behaviour of some hybrids in the Mallard Group. - Animal Behaviour, 1961 - Elsevier
• Miller DB and Gilbert Gottlieb G. Maternal vocalizations of mallard ducks (Anas platyrhynchos) . Animal Behaviour. Volume 26, Part 4, November 1978, Pages 1178-1194.
• Losito MP and Baldassarre GA. Pair-Bond Dissolution in Mallards. The Auk, Vol. 113, No. 3 (Jul., 1996), pp. 692-695
• Patrick J. Caldwell, Allen E. Snart. A Photographic Index for Aging Mallard Embryos A Photographic Index for Aging Mallard Embryos. The Journal of Wildlife Management, Vol. 38, No. 2 (Apr., 1974), pp. 298-301
• Figley WK and VanDruff LW. The Ecology of Urban Mallards. Wildlife Monographs. No. 81 (Jan., 1982), pp. 3-39.
• RONALD W. OPPENHEIM. SOME ASPECTS OF EMBRYONIC BEHAVIOUR IN THE DUCK (ANAS PLA TYRHYNCHOS). Anim. Behav., 1970, 18, 335-352.
• Abraham RL. Vocalizations of the Mallard (Anas platyrhynchos). The Condor. Vol. 76, No. 4 (Winter, 1974), pp. 401-420
• Evarts S and Williams CJ. Multiple Paternity in a Wild Population of Mallards. The Auk, Vol. 104, No. 4 (Oct., 1987), pp. 597-602.