American black duck (Anas rubripes)

Description

American black duck fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

American black duck description

The American black duck (Anas rubripes) is a large dabbling duck of eastern North America that, contrary its common name, has predominantly dark brown plumage. The head is a contrasting pale greyish, as is the crown, nape and eye stripe. The grey neck is finely streaked, and there is an iridescent, bluish-purple to violet speculum. The wings are dark brown above but white underneath ^{(2) (3) (4) (5)}. The feet are red, as suggested by the American black duck’s scientific name, rubripes, which comes from two Latin words: ruber, meaning red, and pes, meaning foot ⁽⁶⁾. 

The male and female American black duck are similar in appearance, although the female is paler overall and has a greenish-grey instead of bright yellow-green bill. The juvenile resembles the adult, but appears more heavily streaked on the breast and underparts, as the feathers have broad buff margins and dark tips ⁽³⁾. 

The American black duck is similar in appearance to a number of other ducks in the region, particularly the female mallard (Anas platyrhynchos). However, it has the darkest plumage and the least amount of white on the upperwing, as well as redder legs ⁽³⁾. The American black duck may also be identified by its calls, the male producing a reedy ‘raeb’ or ‘raeb-raeb’ and the female a loud ‘quack’ ⁽⁵⁾.

Also known as

black duck, North American black duck.

Size

Length: 53 - 61 cm ⁽²⁾

Weight

1.35 - 4.15 kg ⁽²⁾

American black duck biology

The American black duck dabbles for food at the water surface by filter-feeding, or picks up food from the ground, water surface, or standing seed heads. It upends in shallow water, but will dive down to almost four metres in deeper water. The American black duck consumes a wide variety of food types, including seeds, roots, stems, grain, aquatic plants, aquatic insects, crustaceans, molluscs and some fish ^{(3) (4)}. 

Breeding pairs form in winter, with many birds paired by December. In the southern part of the American black duck’s range, nesting begins as early as February, but nesting may be delayed until May in northern parts of its range. The male defends the nest and the 7 to 12 eggs until the middle of the incubation period ⁽⁵⁾, which lasts for around 26 to 29 days in total ⁽²⁾. The female is responsible for incubating the eggs. Once the ducklings hatch, the female leads the brood to a rearing area which is abundant in invertebrates and vegetative cover ⁽⁵⁾. The ducklings are able to fly at around 60 days and reach sexual maturity within their first year ⁽²⁾.

American black duck range

Widely distributed across eastern North America, the American black duck breeds from Manitoba, east to Labrador and Newfoundland and south along the Atlantic coast to North Carolina. This species sometimes occurs further west, when it is found in large river valleys, such as those of the Tennessee, Detroit and Upper Illinois Rivers ⁽⁷⁾. 

The American black duck is a migratory species, and northern populations move south before the onset of winter, often travelling as far south as Florida, Texas and the Gulf Coast ⁽⁷⁾. Populations along the coast and in the southern part of this species’ range tend to migrate shorter distances ⁽⁸⁾.

American black duck habitat

The American black duck is found in a wide variety of aquatic habitats, including woodland ponds, coastal salt marshes, bogs, lakes, stream margins and the margins of estuaries ^{(3) (8) (9)}. However, it tends to prefer coastal brackish marshes and bays with adjacent agricultural land ⁽⁹⁾. 

This species nests in tree cavities, old bird nests, or on the ground, often as far as one and a half miles from the water’s edge ⁽⁹⁾.

American black duck status

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

American black duck threats

Although not currently considered threatened with extinction, American black duck populations have been in gradual decline since the 1950s ⁽¹⁰⁾. The current global population is thought to be around half its historical size ⁽³⁾. The mallard is increasingly replacing the American black duck as the most common duck on the east coast of North America as it is more suited to nesting in disturbed, degraded habitats. It can also hybridise with this species. The American black duck is also threatened by loss of habitat from draining and filling wetlands for development, as well as pollution from pesticides and acid rain ⁽¹¹⁾. 

This species has been extensively hunted in the past, and during the 1960s as many as half a million individuals were hunted annually ⁽⁷⁾. The American black duck is also particularly vulnerable to disturbance when breeding due to its wary nature, and a nesting female may abandon the clutch if disturbed ⁽³⁾.

American black duck conservation

As a result of concern over its alarming population declines, the American black duck has been the target of numerous conservation measures. Since strict harvest quotas were introduced in 1983, the number of American black ducks taken by hunters has steadily decreased ^{(3) (11)}. The Black Duck Joint Venture (BDJV) was established in 1989 with the primary aims of supporting research on American black duck ecology and identifying threats to this species, as well as trying to increase its breeding population to 640,000 ⁽⁵⁾. Through efforts of the BDJV, an aerial survey was initiated in 1990 to monitor the American black duck’s populations ⁽³⁾. The U.S. Fish and Wildlife Service also continue to purchase and manage land important for migratory, stopover and breeding American black ducks ⁽¹¹⁾. 

Additional conservation recommendations for the American black duck include improving its habitat by flooding wetland areas, creating nesting areas by constructing ditches, small dams and ponds, and creating stands of food plants ⁽⁹⁾.

Find out more

Find out more about the American black duck:

• Cornell Lab of Ornithology: All About Birds - American black duck:
  http://www.allaboutbirds.org/guide/American_Black_Duck/

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Glossary

Brackish

Slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.

Crustaceans

Diverse group of animals with jointed limbs and a hard chitinous exoskeleton characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.

Hybridisation

Cross-breeding between two different species or subspecies.

Incubate

To keep eggs warm so that development is possible.

Invertebrates

Animals with no backbone, such as insects, worms, spiders, and corals.

Molluscs

A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.

Speculum

In birds, a distinct patch of brightly coloured feathers, often iridescent or metallic in appearance, found on the secondary feathers of the wing (the shorter flight feathers along the inner edge of the wing).

References

1. IUCN Red List (June, 2011)
   http://www.iucnredlist.org/
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
3. Longcore, J.R., Mcauley, D.G., Hepp, G.R. and Rhymer, J.M. (2000) American black duck (Anas rubripes). In: Pool,e A. (Ed) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/481/
4. Cornell Lab of Ornithology: All About Birds - American black duck (June, 2011)
   http://www.allaboutbirds.org/guide/American_Black_Duck/
5. Black Duck Joint Venture (June, 2011)
   http://www.blackduckjv.org/
6. Ogilvie, M.A. (1975) Ducks of Britain and Europe. A&C Black Publishers, London.
7. Madge, S. and Burn, H. (1988) Wildfowl: an Identification Guide to the Ducks, Geese and Swans of the World. Christopher Helm Publishers, London.
8. South Dakota Birds and Birding - American black duck (June, 2011)
   http://www.sdakotabirds.com/species/american_black_duck_info.htm
9. U.S. Forest Service - American black duck (June, 2011)
   http://www.fs.fed.us/database/feis/animals/bird/anru/all.html
10. Ducks Unlimited - American black duck (June, 2011)
    http://www.ducks.org/hunting/waterfowl-id/american-black-duck
11. Wells, J.V. (2007) Birder's Conservation Handbook: 100 North American Birds at Risk. Princeton University Press, New Jersey.