Wood Duck: The Duck That Nests in Trees, and How It Came Back

The wood duck, Aix sponsa, is the North American duck that perches on branches and nests in holes in trees, and its ducklings leave the nest by jumping out the day after they hatch. Cornell calls it “one of the most stunningly pretty of all waterfowl”. Look for it on wooded ponds, slow rivers and beaver swamps across much of the United States; in Britain it is an escape from collections. It is also the duck that was feared close to extinction in the early 1900s, and came back.

How to recognise a wood duck

Start with the shape: Cornell describes “a boxy, crested head, a thin neck, and a long, broad tail”. The breeding male has “a glossy green head cut with white stripes, a chestnut breast and buffy sides”, with a bright red eye and a red-and-white bill. The female is “gray-brown with white-speckled breast”, in Cornell’s words, with a “large white teardrop patch around eye”. In late summer, eclipse males “lose their pale sides and bold stripes, but retain their bright eye and bill”.

Cornell gives a length of 47–54 cm (18.5–21.3 in) and a weight of 454–862 g (16.0–30.4 oz); the US Fish and Wildlife Service gives 47–55 cm (18–22 in). Cornell gives no size comparison with the mallard; its size class is “between crow and goose”. The female’s call when disturbed is a loud “oo-eek, oo-eek”; the male has a “thin, rising and falling zeeting whistle”. Audubon’s magazine records another nickname, Squealer Duck.

Wood duck or mandarin duck?

Drakes are no problem; hens are. The BTO says the males “are easy to identify, but the females are confusingly similar.” The mandarin is, in Audubon’s account, the wood duck’s one close relative, and in Britain both occur as escapes, though the mandarin is established and the wood duck probably is not. The GB Non-native Species Secretariat’s identification sheet labels the female mandarin “Less white around the eye than wood duck”, with “Spotting on the flank” and a “Pink bill”. How the mandarin came to breed wild in Britain is told in mandarin duck.

Cornell’s comparison page leaves the mandarin out and uses three North American species instead; the hens of all three, the mallard, the green-winged teal and the thin-billed hooded merganser, lack the wood duck’s white eye patch. That diving duck has its own account in hooded merganser.

Where and when you will see one

In the United States a wood duck can turn up in any month: Cornell says it is “found throughout the year in the U.S.”, and the US Fish and Wildlife Service says it breeds “in most of the central and eastern United States”. Audubon’s summary is “Northern birds migratory; southern females may be permanent residents.” Ducks Unlimited puts the poorly documented autumn departure in October or November, and spring migration from February through April. Look “around the edges of swamps, sluggish streams, overgrown beaver ponds, and wood-fringed marshes”; more on seasonal movement is in duck migration.

In Britain the GB Non-native Species Secretariat says feral wood ducks have been seen “since the late 19th century” but that the species “has yet to establish a sustainable population”; the BTO says breeding has occurred “although the species is probably not established.” It is listed on Schedule 9 of the Wildlife and Countryside Act 1981.

What it eats, and how

Mostly plants, and in autumn and winter above all acorns. Cornell says “plant materials make up 80% or more of what the species eats”, from duckweed to wild cherries, alongside insects and snails. The US Fish and Wildlife Service calls acorns “the primary winter food of choice”. Ducklings “feed exclusively on protein-rich insects and small invertebrates”, according to Audubon’s magazine. The method is mixed: Cornell’s phrase is “dabbling or short, shallow dives”, and Audubon adds “submerging head and neck, occasionally up-ending”. The two styles are compared in dabbling vs diving ducks.

Nesting and ducklings

Wood ducks cannot make their own holes. Cornell says they typically use cavities where a broken branch has let the heartwood rot, “anywhere from 2–60 feet high”; Audubon gives nest sites “up to 65′ above ground”. Cornell calls the wood duck “the only North American duck that regularly produces two broods in one year.” Clutch sizes differ by source: 6–16 eggs from Cornell, 9–14 and sometimes 6–15 from Audubon, 9 to 12 from Ducks Unlimited, nine to 14 from the US Fish and Wildlife Service. The female incubates alone, for 28–37 days according to Cornell, 25–35 according to Audubon and 28 to 30 according to Ducks Unlimited; the male, Ducks Unlimited says, leaves “with onset of incubation.”

Not every egg in a nest belongs to the hen sitting on it. Cornell says egg-dumping “is common in Wood Ducks” and that “in some areas it happens in more than half of all nests”, possibly made more common by nest boxes. A female typically lays 10–11 eggs, but nests holding 29 have been found, and Cornell notes that if boxes are “placed too close together, many females lay eggs in the nests of other females.”

How high do wood duck ducklings jump?

Cornell says the ducklings “may jump from heights of over 50 feet without injury”; Audubon’s magazine words it as nests “as high as 50 feet above the ground or water”. They go the morning after hatching, having climbed to the entrance, as Audubon puts it, “Clinging with sharp claws and bracing with tails”. In a climbing test of newly hatched ducklings of five species in the WWT journal Wildfowl, “The Wood Duck performed consistently best”, climbing “by a series of leaps” with its tail as a brace. The mother calls but, Cornell says, “does not help them in any way”; Audubon’s magazine credits the soft landings to “Downy feathers, pliable bones, and leaf litter”. Life after the jump is covered in ducklings.

How wood ducks are doing

Well, which once looked unlikely. Audubon says that early in the 20th century the species “was thought to be threatened with extinction”, the main cause “probably loss of nest sites due to cutting of large trees, combined with hunting pressure.” Ducks Unlimited quotes early ornithologists’ verdicts, among them “Becoming scarce, likely to be exterminated”. Then, it says, “In 1918, however, the Migratory Bird Treaty Act prohibited the hunting of wood ducks nationwide.” Seasons reopened in 1941, though most states waited until 1959; the Illinois Department of Natural Resources counts the national ban as 23 years.

Then came the boxes. In 1937 the U.S. Biological Survey, forerunner of the US Fish and Wildlife Service, put up 486 wooden boxes at Chautauqua National Wildlife Refuge in Illinois, and over the next two years Arthur Hawkins and Frank Bellrose put up 700 more. Ducks Unlimited says “More than half were used”; the Illinois account says half. Cornell’s verdict now: “Providing predator-resistant nest boxes near ponds has a positive effect on population growth.”

Partners in Flight, quoted by Cornell, puts the global breeding population at 4.6 million, a species of low conservation concern; the US Fish and Wildlife Service says perhaps “as many as 3 million breeding pairs” in North America, and a Service story “over 4 million birds”. Ducks Unlimited calls populations “stable to increasing throughout their range”, and Cornell reports an increase from 1966 to 2019 in the North American Breeding Bird Survey.

A brown hen with a white teardrop round the eye is worth checking against the look-alikes above and then in the wild duck identifier. For the autumn journeys of northern birds, try the Flyway migration game.