The Muscovy duck (Cairina moschata) is a large duck native to Mexico, Central, and South America. Small wild and feral breeding populations have established themselves in the United States, particularly in Florida and the lower Rio Grande Valley of Texas as well as in many other parts of North America, including southern Canada. Feral Muscovy ducks are found in New Zealand, Australia, and in parts of Europe.
They are large ducks, with the males about 76 cm (30 in) long, and weighing up to 7 kg (15 lb). Females are considerably smaller, and only grow to 3 kg (6.6 lb), roughly half the males' size. The bird is predominantly black and white, with the back feathers being iridescent and glossy in males, while the females are more drab. The amount of white on the neck and head is variable, as well as the bill, which can be yellow, pink, black, or any mixture of these. They may have white patches or bars on the wings, which become more noticeable during flight. Both sexes have pink or red wattles around the bill, those of the male being larger and more brightly colored.
Although the Muscovy duck is a tropical bird, it adapts well to cooler climates, thriving in weather as cold as -12 °C (10 °F) and able to survive even colder conditions. In general, Barbary duck is the term used for C. moschata in a culinary context.
All Muscovy ducks have long claws on their feet and a wide flat tail. In the domestic drake (male), length is about 86 cm (34 in) and weight is 4.6–6.8 kg (10–15 lb), while the domestic hen (female) is much smaller, at 64 cm (25 in) in length and 2.7–3.6 kg (6.0–7.9 lb) in weight. Large domesticated males often weigh up to 8 kg (18 lb), and large domesticated females up to 5 kg (11 lb).
The true wild Muscovy duck, from which all domesticated Muscovys originated, is blackish, with large white wing patches. Length can range from 66 to 84 cm (26 to 33 in), wingspan from 137 to 152 cm (54 to 60 in) and weight from 1.1–4.1 kg (2.4–9.0 lb) in wild Muscovys. On the head, the wild male has short crest on the nape. The bill is black with a speckling of pale pink. A blackish or dark red knob can be seen at the bill base, and the bare skin of the face is similar to that in color. The eyes are yellowish-brown. The legs and webbed feet are blackish. The wild female is similar in plumage, but is also much smaller, and she has feathered face and lacks the prominent knob. The juvenile is duller overall, with little or no white on the upperwing. Domesticated birds may look similar; most are dark brown or black mixed with white, particularly on the head. Other colors such as lavender or all-white are also seen. Both sexes have a nude black-and-red or all-red face; the drake also has pronounced caruncles at the base of the bill and a low erectile crest of feathers.
C. moschata ducklings are mostly yellow with buff-brown markings on the tail and wings. For a while after hatching, juveniles lack the distinctive wattles associated with adult individuals, and resemble the offspring of various other ducks such as Mallards. Some domesticated ducklings have a dark head and blue eyes, others a light brown crown and dark markings on their nape. They are agile and speedy precocial birds.
The drake has a low breathy call, and the hen a quiet trilling coo.
The karyotype of the Muscovy duck is 2n=80, consisting of three pairs of macrochromosomes, 36 pairs of microchromosomes, and a pair of sex chromosomes. The two largest macrochromosome pairs are submetacentric, while all other chromosomes are acrocentric or (for the smallest microchromosomes) probably telocentric. The submetacentric chromosomes and the Z (female) chromosome show rather little constitutive heterochromatin (C bands), while the W chromosomes are at least two-thirds heterochromatin.
Male Muscovy ducks have spiralled penises which can become erect to 20 cm (7.9 in) in one third of a second. Females have cloacas that spiral in the opposite direction that appear to have evolved to limit forced copulation by males.