Mallard (Anas platyrhynchos): Facts, Diet, Habitat and Ducklings

Appearance: drake, hen and duckling

Mallards are a classic example of a bird in which the sexes look completely different, a trait called sexual dimorphism.

• Breeding drake (male): glossy bottle-green head, a narrow white collar, a purple-brown (chestnut) breast, a pale gray body and a black rear with white tail edges. Two black central tail feathers curl upward in a small loop, the “drake curl”. The bill is yellow.
• Hen (female): mottled brown and buff all over, with a darker crown and a dark line through the eye. Her bill is orange with a dark saddle or blotches.
• Both sexes: a shining blue to purple patch on the wing, called the speculum, framed by white bars in front and behind. It is easy to see in flight and often visible on a resting bird.

The drake’s green is not a pigment. It is structural color, produced by the microscopic arrangement of melanin granules in the feathers, which is why the head can flash green, blue or even purple as the light changes. Read more in why are male ducks so colorful?

Ducklings hatch covered in dark brown down with yellow on the face and underside and a dark stripe through the eye. At about two months they look like small, streaky hens, and young males gain their green heads during their first fall.

Eclipse plumage

Each summer, after the breeding season, drakes molt into a dull brown “eclipse” plumage that looks very like the hen’s. At the same time they shed all their flight feathers at once and cannot fly for roughly three to four weeks. The camouflage helps them hide while they are grounded. An eclipse drake can still be told from a hen by his plain yellow-olive bill. By early fall the drakes are back in full color, ready for pairing.

Size: how big is a mallard?

The mallard is a medium-large duck and somewhat heavier than most other dabbling ducks.

Drakes are generally larger than hens, and birds from the cold north tend to be larger than those from the south. Mallards in Greenland form a distinct, large subspecies (A. p. conboschas) with a shorter bill, a good example of the rule that warm-blooded animals in cold climates tend to be bigger and stockier.

Domestic breeds descended from the mallard vary far more: some heavy meat breeds weigh well over twice as much as a wild bird and can barely fly.

Habitat and range

Mallards live in almost any shallow fresh or brackish water: marshes, ponds, lakes, slow rivers, reservoirs, flooded fields, estuaries and sheltered coasts. They prefer water less than about 1 m (3 ft) deep, where they can reach the bottom by tipping up. Few other wild birds have adapted so well to people; park lakes, canals, golf courses and even garden ponds are part of their habitat.

The native range covers most of the Northern Hemisphere, from Alaska, Canada and the United States to Mexico, and from Iceland and Britain across Europe and Asia to Japan, plus parts of North Africa. Mallards have also been introduced to Australia, New Zealand, South Africa, Hawaii and several South American countries.

Northern populations are strongly migratory. In North America, many mallards breed on the prairie potholes and boreal wetlands of Canada and the northern United States and spend the winter in the southern states and northern Mexico. In milder regions, such as much of western Europe, many mallards stay all year, joined in winter by migrants from colder countries.

Diet: what do mallards eat?

Mallards are omnivores and opportunists. They feed mainly by dabbling: swimming with the bill at the surface, filtering mouthfuls of water and mud, or “upending” with the tail in the air to reach plants on the bottom. They rarely dive for food. On land they graze and pick up grain from fields.

Their natural diet includes:

• seeds of grasses, sedges and water plants, and waste grain such as corn, wheat and rice
• leaves, roots and tubers of aquatic plants
• snails, insects and their larvae (such as caddisflies, midges and beetles), worms and small crustaceans
• occasionally tadpoles, frogs and small fish

The balance changes through the year. Plants dominate in fall and winter, while laying hens switch to a diet that is mostly animal food, which supplies the protein and calcium needed to make eggs. Ducklings also eat mainly insects in their first weeks.

Behavior and calls

Outside the breeding season, mallards are highly social and gather in flocks that can number hundreds or thousands on good wintering grounds. They are active by day and by night, often flying out to fields to feed at dusk.

The famous quack

The loud, classic “quack” belongs to the hen. Her best-known call is a series of quacks that start loud and fade away, known as the decrescendo or hail call, which she uses to call her mate or her ducklings. The drake does not quack like this. His usual call is a quieter, rasping “raeb” and a soft whistle given during courtship displays.

On take-off, a mallard’s wings make a faint whistling sound, and the birds can spring almost straight up out of the water, an advantage on small, tree-lined ponds.

Staying dry and warm

Mallards spend hours each day preening, spreading oil from a gland near the tail and zipping their feathers back into a tight, water-shedding coat. You can read how this works in how do ducks stay dry? In winter they stand on ice for hours without harm thanks to a clever heat-exchange system in the legs, explained in why don’t ducks’ feet freeze?

Mallards were also the species in which scientists first showed that birds can sleep with one half of the brain while the other half stays alert, keeping one eye open for predators.

Reproduction: nests, eggs and ducklings

Mallard courtship starts in fall, months before nesting. Groups of drakes perform displays such as the “grunt-whistle” and “head-up-tail-up” in front of hens, and by winter most adults are paired. Pairs fly to the breeding grounds together, and the female usually chooses the nest site.

The nest is a shallow scrape on the ground, hidden in tall grass, reeds or under bushes, often near water but sometimes hundreds of meters away. Mallards are flexible and also nest in tree holes, on flower boxes, balconies and flat roofs. The hen lines the nest with plant material and down plucked from her own breast.

• Clutch: usually 8–13 creamy to greenish-buff eggs, laid about one a day
• Incubation: about 27–28 days, by the hen alone, starting when the clutch is nearly complete so all the eggs hatch together
• Ducklings: precocial, meaning they hatch with open eyes and a coat of down and can walk, swim and feed themselves within a day
• Fledging: the young can fly at about 50–60 days old

The drake usually leaves soon after incubation begins and joins other males to molt. The hen leads the brood to water within a day of hatching and guards them, brooding them under her body when they are cold. Ducklings imprint on their mother and follow her closely. Losses to predators are heavy, so many hens lay a replacement clutch if the first nest is destroyed.

Lifespan

Most wild mallards live only a few years; the average life expectancy is often given as about 3 years. Hunting, predators, collisions and disease all take a toll. Birds that survive their first year can live much longer, and the oldest banded wild mallard on record in North America lived more than 26 years.

Predators and threats

Eggs and ducklings face a long list of predators: red foxes, raccoons, skunks, mink, crows, gulls, herons, large fish such as pike, snapping turtles and domestic cats. Adults are taken by foxes (especially hens on the nest), coyotes, eagles, large falcons and some owls.

Other threats include wetland drainage, collisions with vehicles and power lines, lead poisoning from old shot and sinkers, and outbreaks of avian botulism and avian influenza in hot, crowded conditions.

Conservation status

The IUCN Red List classes the mallard as Least Concern. It has an enormous range and a global population estimated at well over 17 million mature birds, although the overall trend is now considered to be decreasing. In North America, mallard numbers are monitored every spring by aerial surveys of the breeding grounds, and hunting seasons are set according to the results.

Mallards as a problem species

Mallards are so adaptable that they cause problems for some relatives. Where released or feral mallards spread, they hybridize readily with closely related ducks, threatening the genetic identity of the American black duck, the mottled duck in Florida, the Hawaiian duck, the Pacific black duck in New Zealand and the yellow-billed duck in southern Africa. The mallard is regarded as invasive in New Zealand, Australia and South Africa for this reason.

Mallards have been recorded hybridizing with dozens of other duck species. Close relatives such as the Mexican duck were long treated as mallard subspecies; the American Ornithological Society recognized the Mexican duck as a separate species again in 2020.

Mallards and people

The mallard was domesticated in Southeast Asia thousands of years ago, and farm ducks were also kept by the ancient Romans. Today almost every domestic duck breed, including the Pekin, Rouen, Khaki Campbell, Call duck and Indian Runner, is a mallard at heart, and wild and domestic birds can interbreed freely. That is why park ponds often hold odd-looking “mallards” with white patches or unusual colors.

Mallards are also the most important game duck in North America and Europe, the classic subject of bird art and decoys, and for many children the first wild bird they learn to name.

Myth: a duck’s quack doesn’t echo

A popular claim says a duck’s quack never echoes. It does. In 2003, acoustics researchers at the University of Salford in England recorded a duck quacking in a reverberation chamber and showed a clear echo. The quack fades gently at the end, so the echo blends in and is simply hard to hear.

Mallard vs other ducks and geese

The hen mallard is easily confused with other brown female ducks, such as the gadwall, the American black duck and the mottled duck; look for her orange-and-dark bill and the blue speculum with white borders. Mallards are much smaller than geese, with shorter necks and broader, flatter bills, as explained in duck vs goose. Mallards often share park lakes with the Canada goose, the other big waterbird most people in North America and northern Europe know by sight.