Duck Facts: What Is True and What Is Not

• The quack belongs to one sex of one species. "The standard duck's quack is the sound of a female Mallard. Males don't quack; they make a quieter, rasping sound" (Cornell Lab of Ornithology). Across the wider duck family, many species whistle, grunt, coo or growl rather than quack at all.
• Nearly every domestic breed is a Mallard. Pekin, Rouen, Indian Runner and Khaki Campbell all descend from the wild Mallard. The Muscovy is a separate species (Cairina moschata) native to the Neotropics — from the Rio Grande Valley of Texas and Mexico south through Central and South America — domesticated independently in the pre-Columbian Americas.
• Chinese domestic ducks have two wild ancestors, not one. A 2023 study in Animals concluded that both the Mallard (Anas platyrhynchos) and the Eastern Spot-billed Duck (A. zonorhyncha) contributed to the evolution of domestic ducks in China, so "all domestic ducks are Mallards" is close but not exact.
• Migration speed is an estimate, not a measurement. Migrating flocks of Mallards have been estimated to travel at around 55 miles per hour.
• Ducklings walk out of the nest inside a day. Newly hatched Mallards are covered in down and alert, eyes open, and are ready to leave the nest within 13 to 16 hours.
• Wood Duck ducklings jump out of trees. They hatch in tree cavities and leave a day later by leaping to the ground, from heights of over 50 feet, without injury.
• One North American duck raises two broods a year. The Wood Duck is the only one that regularly produces two broods in a single year.
• The Long-tailed Duck is the extreme diver. It can dive as deep as 200 feet to forage. Of all the diving ducks, Long-tailed Ducks spend the most time underwater — 3 to 4 times as long submerged as on the surface.
• A shoveler's bill works as a colander. The Northern Shoveler's bill is about 2.5 inches long and shaped like a shovel, with roughly 110 fine projections called lamellae along the edges that filter tiny crustaceans, seeds and aquatic invertebrates out of the water.
• Half the brain can stay awake. Mallards can sleep with one hemisphere awake and the contralateral eye open. Birds at the exposed ends of a row did this about 150% more than birds in the protected middle, and when they did, they preferentially aimed the open eye away from the group — the direction a predator would come from. Middle birds either closed both eyes or showed no side preference.
• One in three ducks shot in North America is a Mallard. It is the most heavily hunted North American duck, accounting for about 1 of every 3 ducks shot.
• Waterfowl genitalia are a co-evolutionary arms race. "Ducks are the only birds with penises" is wrong: most birds lost the organ, but waterfowl, ratites and tinamous kept it. Male waterfowl have a phallus whose length ranges from 1.5 cm to over 40 cm depending on species, and females have vaginas that spiral in the opposite direction, with vaginal complexity tracking phallus length across species.
• Day-old ducklings grasp "same" and "different". In Oxford research published in Science in 2016, newly hatched ducklings learned an abstract relationship from a single imprinting exposure with no reward training. About three-quarters preferred to follow the stimulus pair exhibiting the relationship they had learned.
• Eiderdown has been harvested for more than 1,000 years. Common Eiders line their nests with down plucked from their own breast, and people have gathered that down from empty nests for over a millennium. Icelandic eider "farmers" build wooden huts to encourage the birds to nest.
• Hunters pay for the habitat. The US Federal Duck Stamp, required of waterfowl hunters since 1934, has raised more than $700 million and helped conserve over 5.2 million acres of habitat.
• New Zealand's Gray Ducks have been genetically swamped. Mallards released from the 1860s onward interbred so heavily with the native Gray Duck that the majority of sampled birds now represent a Gray Duck x Mallard hybrid swarm; only about 6-10 percent are genetically pure Gray Ducks.
• A healthy-looking duck can be carrying bird flu. In USGS experiments, captive ruddy ducks and lesser scaup inoculated with highly pathogenic avian influenza showed no outward clinical signs — they appeared healthy even when the infection eventually killed them. Absence of visible illness therefore cannot be used to judge whether a diving duck is infected.

"A duck's quack doesn't echo — and nobody knows why." It echoes like any other sound. In 2003 Professor Trevor Cox at the University of Salford's acoustics research centre recorded a duck called Daisy in an anechoic chamber and then a reverberation chamber, and simulated her quacking in a concert hall and off a cliff. The echo is there. It is simply quiet, and it arrives on the tail of an already-fading sound, so the ear struggles to separate the two.

"Ducks mate for life." Most ducks are seasonally monogamous — Ducks Unlimited puts seasonal monogamy at about 49 percent of all waterfowl species. Pairs form on the wintering grounds and the bond typically lasts only until the eggs are laid, after which the drake leaves and the female raises the brood alone. A new mate is chosen the following winter. Lifelong reunion is suspected in a few sea ducks — goldeneyes, buffleheads, harlequins, eiders — but it is the exception, not the rule.

"A drake Mallard's head is green because the feathers contain green pigment." There is no green pigment anywhere in the bird. The head feathers contain dark melanin packed into nanoscale layered stacks inside the barbules, and those layers reflect light like a photonic mirror. The colour is produced by physics, not chemistry — which is why the head shifts to blue or violet as you change viewing angle, and why it looks nearly black in dull light.

"Feeding bread to ducks and swans gives them angel wing." Angel wing is real, but the bread link is unevidenced — Prof. Christopher Perrins (Oxford Dept. of Zoology), quoted in the Queen's Swan Marker's 2018 statement: "There is no evidence of a connection between feeding bread and angel-wing; at least some cygnets develop this condition without ever having seen any bread." That statement concerns swans and cygnets rather than ducks, and it goes further than a simple correction: it argues against the "ban the bread" campaign and encourages the public to keep feeding swans.

"Ducks can stand on ice because their feet have no nerves or blood vessels." Their feet are fully supplied with both. What they have is a countercurrent heat exchanger: outgoing warm arterial blood runs against incoming cold venous blood, handing over its heat before it ever reaches the toes. In ducks and gulls a dense mesh of intertwined vessels called the rete mirabile, or "wonderful net," amplifies the effect. The foot is deliberately allowed to run close to freezing — that is the trick, not numbness.

Donald Duck arrived first among the cartoon ducks, debuting on 9 June 1934 in the Silly Symphonies short The Wise Little Hen, animated by Dick Lundy. Warner Bros. answered on 17 April 1937 with Daffy Duck in Porky's Duck Hunt, directed by Tex Avery.

Picture books got there before either of them. Beatrix Potter published The Tale of Jemima Puddle-Duck in 1908, and Robert McCloskey's Make Way for Ducklings followed in 1941 — he bought four live mallards and kept them in his apartment so he could sketch them, and the book won the Caldecott Medal in 1942.

Television produced the family's biggest hit song. "Rubber Duckie," written by Jeff Moss and sung by Jim Henson as Ernie, first aired on Sesame Street on 25 February 1970 and climbed to No. 16 on the Billboard Hot 100 that September. Ernie's duck now sits in the Smithsonian's National Museum of American History.

Nintendo's Duck Hunt shipped for the Famicom in April 1984 and became an NES launch title in North America in October 1985. Advertising supplied the last great duck: the Aflac duck, voiced by Gilbert Gottfried, first aired on 1 January 2000 and pushed the insurer's name recognition from 12 percent to 71 percent.

Daisy was a duck borrowed by the University of Salford in 2003. Professor Trevor Cox recorded her quacking inside an anechoic chamber and then a reverberation chamber to settle whether a quack echoes. It does. The Guardian reported the verdict that September, and the experiment remains the standard citation whenever the myth resurfaces.

Trevor was a lone mallard who blew onto the Pacific island of Niue, which has no natural ponds or wetlands. After New Zealand Herald journalist Claire Trevett wrote about him in September 2018 he became world news, and locals took to giving directions by reference to him.