Wood duck (Aix sponsa)

Also known as: acorn duck, American wood duck, Carolina duck, Carolina wood duck, squealer, summer duck, woodie
Synonyms: Anas sponsa
KingdomAnimalia
PhylumChordata
ClassAves
OrderAnseriformes
FamilyAnatidae
GenusAix (1)
SizeLength: 47 - 54 cm (2) (3)
Wingspan: 66 - 75 cm (4) (5)
Male weight: 544 - 862 g (2)
Female weight: 499 - 862 g (2)
Top facts

The wood duck is classified as Least Concern (LC) on the IUCN Red List (1).

A brightly coloured and distinctively patterned bird, the wood duck (Aix sponsa) is considered to be one of the most stunning of all waterfowl (4) (6). Its scientific name, Aix sponsa, aptly translates as “waterbird in bridal dress”, referring to the flamboyant breeding plumage of the adult male (2) (6).

A relatively small duck (2) (3), the wood duck has a crested head, a thin neck, short, broad wings and a large, rectangular tail (3) (4). During the breeding season, the colourful male is blackish above, with a bronze, green and purple iridescence (3) (5). It has a purplish neck and breast marked with white triangular spots, and the lower breast and belly are white. The flanks of the male wood duck are buffy yellow, bordered in front by broad black and white vertical lines, and above and to the rear by finer black and white crescents (2) (3) (5).

The male wood duck’s wings are largely metallic blue, green and black above, with a few white markings, and dark brown below (2) (5). The tail is black with a bronze sheen (3). The feathers on the side of the rump are elongated, and are reddish-violet with orange stripes (3) (5).

The head and long, shaggy crest of the male wood duck are mainly black with a green, blue and purple iridescence (2) (3) (5). The face is ornately marked with thin white lines from the top of the beak, over the eye and through the crest, and from behind the eye through the base of the crest. The chin and throat are white, with white, finger-like markings extending onto the cheek and neck. This attractive patterning is further enhanced by the bright red eye and reddish beak, which has a black tip, a white patch on the front of the upper mandible, and a bright yellow line at the base. The legs and feet of the male wood duck are orange-yellow, with dusky webbing (3) (5).

The female wood duck is much less brightly coloured than the male, being largely olive-brown to greyish, with a purple, green or bronze sheen on the upperparts, white mottling on the breast and sides, and a white belly. Like the male, the female wood duck has a shaggy crest, but the head and crest are mainly dark greyish, with a green and purple gloss, a narrow white line around the base of the beak, a white patch around the eye, and a white chin and throat. The female has a dark grey beak, dark brown eyes, and yellowish-grey legs and feet, with dark webbing (2) (3) (5).

In late summer, the male wood duck briefly moults into ‘eclipse plumage’ while the flight feathers are replaced. During this time, the male more closely resembles the female, but retains the red eye, white cheek lines and colourful beak (2) (3) (4) (5). After breeding, the female becomes duller and browner, with a reduced white eye patch and reduced crest (5).

The juvenile wood duck resembles the adult female, but is duller, with a less obvious white eye patch, buff streaking on the breast and sides, and a streakier belly (5). Juvenile males begin to show white on the throat and face from around three months old (2). Ducklings are dark brown above and yellowish below and on the face, with a dark stripe across the eyes (2) (3).

The male wood duck’s distinctive plumage makes it difficult to confuse with any other duck species (2) (3). However, the female and juvenile are quite similar in appearance to the female and juvenile mandarin duck (Aix galericulata), which is sometimes present as a feral species within the wood duck’s range. The female wood duck is generally darker and less grey than the female mandarin duck, and has a more distinct eye patch (2) (3) (5). Although the male mandarin duck is colourful and ornate like the male wood duck, it differs mainly in its white and orange rather than dark black and green head (3) (4).

The calls of the male wood duck include a thin, high, rising and falling whistle, and a ‘burp’ call made during courtship. The female produces a variety of calls, including a loud ‘oo-eek, oo-eek’ when disturbed or taking flight (2) (3) (4) (5). The wood duck’s wings make a whistling sound in flight (2) (3).

The wood duck is widespread across North America. A small Pacific coast population breeds from British Columbia in Canada to Washington and California in the United States, while a larger population breeds from Manitoba east to Nova Scotia, and south to Texas, Florida and the Gulf of Mexico (2) (3) (5) (6). This species also breeds in Cuba (3) (5).

The wood duck is partially migratory, with northern populations moving to southern parts of the range for the winter, reaching as far south as Mexico (2) (3) (5) (6). Other wood duck populations are resident year-round (2) (3) (6).

The breeding habitat of the wood duck includes areas of standing or slow-moving freshwater in wooded areas (5), including wooded swamps, freshwater marshes, streams, small lakes and beaver ponds (2) (3) (4). Habitats with a mixture of open water and abundant vegetative cover are preferred (3) (4).

In winter, the wood duck may use more open forested wetlands (2) (3) (5) (6).

The wood duck has a varied diet that includes a range of seeds, fruits and aquatic and terrestrial invertebrates (2) (3) (4) (6). It typically forages in shallow water, dabbling at the surface or sometimes upending, but only rarely diving (2) (3) (4). However, when aquatic foods are less available, the wood duck will also forage on the forest floor for acorns and other nuts and seeds, or sometimes feed on grain in fields (3) (4). Plant material usually makes up most of the diet (4) (6), but insects and other invertebrates are particularly important for ducklings and breeding females (2) (3) (6).

Unusually among waterfowl, the wood duck commonly perches in trees (2) (3), being one of only a few duck species with strong claws for perching and for gripping bark (4). Its broad tail and short, broad wings make the wood duck highly manoeuvrable as it flies through the forest canopy (3) (4), while its large eyes and good vision help it to avoid colliding with branches (3).

The wood duck does not generally form flocks, except at roosts in autumn and winter, when groups of up to 1,000 sometimes occur (2) (3). This species is monogamous (2) (3), and males will defend their mates if approached too closely. However, the wood duck is not territorial, and nesting sites are not defended (2) (3) (4).

During courtship, the male wood duck swims in front of the female with its wings and tail elevated, and may also perform ritualised preening and shaking movements (4). The timing of the breeding season varies across the wood duck’s range, with southern populations starting to breed as early as January or February, while northern populations usually breed from March or April (2) (3).

Unlike most waterfowl, the wood duck nests in holes in trees, either in a natural cavity or sometimes in a hole made by a pileated woodpecker (Dryocopus pileatus). This species also readily uses man-made nest boxes (2) (3) (4) (6). The female wood duck usually selects the nest site, accompanied by the male (2) (3) (4), with trees near water generally being preferred (3) (4) (6). The nest is lined with downy feathers from the female’s breast (3) (4).

The female wood duck usually lays a clutch of around 6 to 16 creamy white to tan-coloured eggs (4), which she incubates for 25 to 37 days (3). The young wood ducks are well developed at hatching, and are able to leave the nest within the first day. After using their long tails and sharp claws to climb the inner side of the nest cavity, the young wood ducks must make the long jump from the nest entrance to the ground, encouraged by the female calling to them from below (2) (3) (4). Young wood ducks have been known to leap from great heights without injury (3) (4).

The young wood ducks are able to fly after about eight to ten weeks (2) (4). Female wood ducks often re-nest if the first clutch of eggs is lost, and some females, particularly in more southerly populations, may produce a second clutch after the first has successfully hatched (2) (3). The wood duck is the only North American duck that regularly produces two broods a year (3) (4). Both male and female wood ducks are able to breed for the first time in the year following their hatching (2) (3).

Female wood ducks often lay eggs in the nests of other females, a behaviour known as ‘dump nesting’. This often occurs where nests are placed close together and are highly visible, and may relate to competition between females for suitable nest holes (2) (4) (6). It can sometimes result in nests containing up to 30 or more eggs (6).

The wood duck may also lay eggs in the nests of other cavity-nesting species, such as the hooded merganser (Lophodytes cucullatus) (2), a species which will in turn sometimes lay its own eggs in the nests of wood ducks (3). The wood duck also commonly competes for suitable nesting holes with species such as squirrels, honey bees, hooded mergansers, the introduced European starling (Sturnus vulgaris), and other birds (2).

Wood duck eggs are vulnerable to a range of predators, including snakes, mink, racoons and woodpeckers, while ducklings may be taken by snapping turtles (Chelydra serpentina), American bullfrogs (Rana catesbeiana), fish and alligators. Nesting females are sometimes taken by foxes, racoons and snakes (2) (3). Young wood ducks often escape predators by diving underwater (3).

The wood duck population fell sharply at the start of the 20th century, largely due to overhunting for its meat and feathers. This attractive waterbird was at one point believed to be in danger of extinction, but it has since made a dramatic recovery as a result of various conservation measures (2) (3) (5).

A popular game bird, the wood duck is the second most commonly shot duck in the Mississippi and Atlantic flyways, where it comprises around ten percent of the annual waterfowl harvest (2) (3). Despite this, it is now one of the most common breeding waterfowl species in North America (2) (3), with a large and widespread population, which appears to be increasing (3) (7).

Perhaps the greatest future threat to the wood duck comes from habitat loss and degradation, due to the drainage of swamps and other human activities which alter or destroy forested wetlands (2) (3) (6). A considerable proportion of the wood duck population is now reported to breed in artificial nest boxes (2).

Small numbers of wood ducks have escaped or been released in countries outside of the species’ natural range, such as in the United Kingdom. Although it currently only occurs in small numbers in the UK, the wood duck may have the potential to compete with native bird species for nesting cavities in trees (8).

The decline and subsequent recovery of this colourful waterbird is a good example of how effective conservation measures can have a significant impact on the success of a species (6). The recovery of the wood duck population was due in large part to protection from overharvesting after the introduction of the Migratory Bird Treaty Act of 1918, which ended unregulated hunting (2) (3) (6).

This species’ recovery was further aided by expanding beaver populations, which help to create the type of wetland habitat the wood duck favours, as well as by nestbox schemes to improve nest site availability (2) (3) (5). Natural cavities are often scarce, but the wood duck readily uses artificial nest boxes (3) (4), although if these are placed too close together or are too highly visible it may sometimes result in increased ‘dump nesting’ by females (4).

Recommended conservation measures for the wood duck include protecting and restoring its wetland habitats, for example by reducing stream channelisation, establishing trees and shrubs along stream banks, and reducing drainage of wet woodlands (3) (6). The effects of forest management practices on the availability of natural nesting cavities should also be examined (3). Any increase in the harvest rate of this species should be considered carefully and only permitted if it would not negatively affect the wood duck population (3).

Methods to more accurately assess wood duck populations have also been recommended, so that the effects of habitat changes and conservation efforts on this species can be properly evaluated (3).

Find out more about the wood duck and its conservation:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (March, 2012)
    http://www.iucnredlist.org/
  2. Kear, J. (2005) Ducks, Geese and Swans. Volume 2: Species Accounts (Cairina to Mergus). Oxford University Press, Oxford.
  3. Hepp, G.R. and Bellrose, F.C. (1995) Wood duck (Aix sponsa). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
    http://bna.birds.cornell.edu/bna/species/169/
  4. The Cornell Lab of Ornithology: All About Birds - Wood duck (April, 2012)
    http://www.allaboutbirds.org/guide/wood_duck/lifehistory/ac
  5. Ogilvie, M.A. and Young, S. (2002) Photographic Handbook: Wildfowl of the World. New Holland Publishers, London.
  6. USDA-NRCS Wildlife Habitat Management Institute and Wildlife Habitat Council: Fish and Wildlife Habitat Management Leaflet - Wood duck (Aix sponsa) (April, 2012)
    ftp://ftp-fc.sc.egov.usda.gov/WHMI/WEB/pdf/woodduck%281%29.pdf
  7. BirdLife International - Wood duck (April, 2012)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=417
  8. GB Non-native Species Secretariat (NNSS): Identification Sheet - Wood duck (October, 2013)
    https://secure.fera.defra.gov.uk/nonnativespecies/index.cfm?sectionid=47