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The Mallard, also known as the Wild Duck, is a recognizable duck species known for its green head and brown body. This dabbling duck breeds in temperate and subtropical regions across the Americas, Eurasia, and North Africa and has been introduced to several other countries.
The mallard belongs to the Anatinae subfamily of the Anatidae family and is characterized by its size, which is medium in comparison to other dabbling ducks. The male mallard has purple patches on its wings, while the female has brown-speckled plumage. Both sexes have a speculum on their wings, which is a strip of iridescent blue or black feathers bordered by white. The mallard measures 50–65 cm in length and has a wingspan of 81–98 cm, with a bill length of 4.4 to 6.1 cm. It is slightly heavier than most other dabbling ducks, weighing between 0.7–1.6 kg.
Mallards inhabit wetlands, where they feed on water plants and small animals. They are social animals and tend to live in flocks of varying sizes. The female mallard lays 8 to 13 eggs, which are creamy white to greenish-buff in color and spotless. The incubation period lasts 27 to 28 days and the ducklings take 50 to 60 days to fledge. They are precocial and capable of swimming as soon as they hatch.
The mallard, scientifically known as Anas Platyrhynchos, is a species of duck that is categorized as least concern
by the International Union for Conservation of Nature (IUCN). Despite this designation, the mallard is considered invasive in some regions due to its ability to adapt to urban environments and interbreed with other wild duck species, leading to genetic pollution and the potential extinction of indigenous waterfowl. The mallard is the primary ancestor of many domestic duck breeds, and its wild gene pool has been influenced by the introduction of domestic and feral populations.
The mallard was originally described by Carl Linnaeus in his 1758 publication Systema Naturae
. Linnaeus gave the species two binomial names, with Anas Platyrhynchos ultimately being recognized as the official scientific name. The name Anas Platyrhynchos is derived from Latin and Ancient Greek, with Anas meaning duck and platyrhynchos meaning broad-billed. In 2013, the genome of the mallard was sequenced.
The term mallard was initially used to describe any wild male duck. Although its exact origin is not certain, it is thought to have originated from the Old French word malart or mallart meaning wild drake. Some suggest that it may have been influenced by the Old High German proper name Madelhart or the word masle meaning male.
The mallard is known for its tendency to interbreed with other closely and distantly related species in the genus Anas, leading to the creation of various hybrids that are capable of producing fertile offspring. This is a unique characteristic of the mallard, which is thought to have evolved rapidly and recently during the Late Pleistocene. Despite this, the distinct lineages of the mallard species remain separate due to behavioral differences and non-overlapping habitats. Mallards and their domestic counterparts are also capable of interbreeding.
Genetic analysis has revealed that some mallards are more closely related to their Indo-Pacific relatives, while others are related to their American relatives. The mallard is believed to have evolved in the area of Siberia, as suggested by the mitochondrial DNA data for the D-loop sequence. Mallard bones have been found in the remains of ancient humans and fossil deposits in Europe, with no clear evidence of a local predecessor species. The large Ice Age subspecies that made up the European and West Asian populations during the Pleistocene is referred to as Anas platyrhynchos palaeoboschas.
The mallard displays distinct differences in its mitochondrial DNA between North American and Eurasian populations, however, the genetic structure of its nuclear genome is not well defined. Mallards in the area surrounding the Bering Sea have haplotypes that are typically found in American mallard relatives and eastern spot-billed ducks. The mallards in the Aleutian Islands are considered to be evolving into a separate subspecies due to the limited gene flow with other populations.
The similarity in the genome of Old World and New World mallards is reflected in the lack of morphological differences between them. Birds such as the Chinese spot-billed duck are highly similar to the Old World mallard, while others like the Hawaiian duck have a closer resemblance to the New World mallard.
The size of mallards can vary from region to region, with birds from Greenland being larger but having smaller bills, lighter plumage, and stockier bodies compared to those further south. These differences in size and physical characteristics have led to the classification of the Greenland mallard as a separate subspecies, known as A. p. conboschas.
The mallard is a medium-sized duck species that tends to be slightly heavier than other dabbling ducks. It measures 50-65 cm (20-26 in) in length, with a wingspan of 81-98 cm (32-39 in) and a weight of 0.7-1.6 kg (1.5-3.5 lb). The body of the mallard makes up about two-thirds of its overall length, with the wing chord measuring 25.7-30.6 cm (10.1-12.0 in), the bill 4.4-6.1 cm (1.7-2.4 in), and the tarsus 4.1-4.8 cm (1.6-1.9 in).
The male mallard is easily recognizable with its gleaming bottle-green head and white collar that distinguishes the head from the purple-tinged brown breast. Its wings are grey-brown and its belly is pale gray. The male mallard's rear is black and has dark tail feathers with white borders. The bill of the male is yellowish-orange with a black tip, while the bill of the female is generally darker, ranging from black to mottled orange-brown.
The female mallard has a mottled appearance, with sharp contrasts in feather color from buff to dark brown, a pattern common among female dabbling ducks. She has buff cheeks, eyebrows, throat, and neck, with a darker crown and eye-stripe.
The male and female mallards both have distinctive iridescent purple-blue feathers with white edges on their wings, which are noticeable during flight or when they are at rest. These feathers are temporarily lost during the summer molt. Newly hatched mallards have yellow plumage on their underbelly and face, with black streaks near the eyes, while their back and the top of their head are black with yellow spots. Their legs and bill are also black. As the duckling approaches one month of age, its plumage starts to resemble the female's, but with more streaks, and its legs lose their dark gray. After two months, the duckling's fledgling period ends, and it is now considered a juvenile. They can fly about 50 to 60 days after hatching.
The bill of the juvenile soon loses its dark gray color, and its sex can be determined by three factors: 1) the bill is yellow in males and black and orange in females, 2) the breast feathers are reddish-brown in males and brown in females, and 3) the center tail feather is curled in males and straight in females. As the juvenile mallard approaches adulthood at 14 months, the plumage of the female remains unchanged, while the plumage of the male gradually changes to its distinctive colors. This change in plumage also applies to adult males during their non-breeding eclipse plumage at the beginning and end of the summer molt. The average life expectancy for mallards is three years, but they can live up to 20 years.
The female mallard may be confused with brown-plumaged females of other duck species such as the gadwall and the American black duck. The gadwall has an orange-lined bill, white belly, black and white speculum, and is a smaller bird. The American black duck is darker than the mallard, while the mottled duck is somewhat darker and has slightly different bare-part coloration and no white edge on the speculum.
Due to the highly variable genetic code of mallards, they can exhibit a wide range of variations, including the faded or "apricot" plumage of this particular female. In captivity, domestic ducks come in wild-type plumages, white, and other colors. These color variants can also be found in domestic mallards kept as pets or aviary birds, which are becoming increasingly available.
The mallard is known for being a noisy species, with the female having the distinctive deep quack that is often associated with ducks. On the other hand, the male mallard makes a sound similar to the female's quack, but it is deeper and quieter. According to research from Middlesex University, mallard vocalizations vary based on the environment, with urban mallards being louder and more vocal than those found in suburban and rural areas. This adaptation is a response to the persistent noise levels produced by human activity.
When incubating a nest or caring for offspring, females use a different vocalization, making a truncated version of the typical quack. This maternal call is highly attractive to their young, and the repetition and frequency modulation of these quacks form the auditory basis for species identification in the offspring. Additionally, if the nest or offspring are threatened, the female will hiss. The wings of a mallard produce a faint whistling noise when taking off.
The mallard is a unique example of both Allen's Rule and Bergmann's Rule in birds. Bergmann's Rule states that polar forms are larger than related forms from warmer climates, and the Greenland mallard, which is larger than mallards further south, is a prime example. On the other hand, Allen's Rule states that appendages such as ears are smaller in polar forms to reduce heat loss, and larger in tropical and desert forms to facilitate heat diffusion. The bill of ducks is equipped with a few blood vessels to prevent heat loss, and in the case of the Greenland mallard, the bill is smaller than that of birds farther south, demonstrating the rule.
The wide distribution range of the mallard, which spans across both the Northern and Southern Hemispheres, is a result of its interbreeding capability due to the variability in its genetic code. This has led to a plethora of hybrids, such as the Brewer's duck, which is a hybrid between the mallard and the gadwall (Mareca strepera). The mallard is found in North America from Alaska to Mexico and the Hawaiian Islands, across the Palearctic from Iceland and southern Greenland to Morocco, Scandinavia, Britain, and Siberia, and even in the east to Australia and New Zealand. During winter, it migrates to the southern regions of its breeding range and may even venture into Central America and the Caribbean. An exceptional instance of a mallard was seen in 2018 on the island of Niue, when a drake named "Trevor" drew media attention for its unexpected presence.
The mallard is a versatile species and can be found in a variety of habitats and climates, from the Arctic tundra to subtropical regions. It can be found in both fresh and saltwater wetlands, including parks, small ponds, rivers, lakes, estuaries, shallow inlets, and even open sea within sight of the coastline. Mallards prefer water depths of less than 3 feet and are attracted to areas with abundant aquatic vegetation.
The mallard's diet is diverse and flexible, and it is an omnivore. The type and amount of food it consumes can vary depending on several factors, including the stage of its breeding cycle, available food options, nutrient availability, and competition with other species. The mallard's diet primarily consists of gastropods, insects, crustaceans, arthropods, worms, seeds, plant matter, and roots and tubers. The proportion of animal matter to plant matter in the mallard's diet may vary between males, non-laying females, and laying females. During the breeding season, male mallards were found to consume 37.6% animal matter and 62.4% plant matter, while non-laying females consumed 37.0% animal matter and 63.0% plant matter, and laying females consumed 71.9% animal matter and only 28.1% plant matter. In general, plant matter makes up a larger portion of the mallard's diet, particularly during autumn migration and the winter.
The mallard typically forages for food by dabbling or grazing, though it has been known to consume frogs as well. In a unique case, a flock of mallards in Romania was seen hunting and eating small migratory birds like gray wagtails and black redstarts. During the non-breeding season, mallards are social and form large flocks called "sordes".
The mallards usually mate and form pairs in the fall in the Northern Hemisphere, with the female laying eggs in spring. After laying the eggs, the male leaves and joins other males to wait for the molting season. During this time, some males remain available to father replacement clutches or mate with isolated females.
The mallards nesting sites are typically on the ground, concealed by vegetation for camouflage. However, they have also been known to nest in tree hollows, boathouses, roof gardens, and balconies, which can sometimes make it difficult for the offspring to reach water.
The mallard's egg clutch typically consists of 8 to 13 creamy white to greenish-buff eggs, without any speckles, that measure approximately 58 mm in length and 32 mm in width. The eggs are laid every other day, and incubation begins when the clutch is almost complete. The incubation period lasts 27 to 28 days and the fledging period takes 50 to 60 days. The mallard ducklings are precocial and capable of swimming as soon as they hatch, but they instinctively stay close to their mother for warmth, protection, and to learn about and remember their habitat and how to forage for food. Female mallards typically do not tolerate stray ducklings and may attack and drive them away, or even kill them. When the ducklings mature into flight-capable juveniles, they learn about and remember their traditional migratory routes, unless they are born and raised in captivity. In New Zealand, where mallards have naturalized, the nesting season is longer, the eggs and clutches are larger, and nest survival is generally greater compared to mallards in their native range.
In the event of a failed nest or brood, some mallards may choose to mate again in an effort to raise a second clutch, typically in the early to mid-summer months. However, in some cases, mallards have been observed breeding during the autumn, such as a female who successfully hatched and raised a clutch of eleven ducklings in November 2011 at the London Wetland Centre.
During the breeding season, both male and female mallards can exhibit aggressive behavior, defending their territory or mate by charging at intruders. Male mallards tend to engage in more fights and attack each other by pecking at their opponent's chest, potentially causing feather loss and even skin damage. Female mallards may also display inciting behaviors, which encourage other ducks to begin fighting. This behavior may allow the female to assess the strength of potential mates.
The mallard is considered an invasive species in Australia and New Zealand, where it competes with the Pacific black duck (known as the gray duck locally in New Zealand) which was over-hunted in the past. There, and elsewhere, mallards are spreading with increasing urbanization and hybridizing with local relatives.
While the keeping of domestic breeds is more popular, pure-bred mallards are sometimes kept for eggs and meat, although they may require wing clipping to restrict flying.