The black-headed duck (''Heteronetta atricapilla'') is a

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

n duck in subfamily Oxyurinae of

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Anatidae The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, flo ...

.HBW and BirdLife International (2021) Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 6. Available at: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip retrieved August 7, 2022 It is found in

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to t ...

, and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved July 24, 2022

Taxonomy and systematics

The black-headed duck is the only member of

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Heteronetta'' and has no subspecies. It is closely related to the "stiff-tailed" ducks of genera '' Nomonyx'', '' Oxyrura'', and ''

Biziura ''Biziura'' is a genus of stiff-tailed ducks endemic to Australasia and containing one living and one subfossil species. Species * †''B. delautouri'' Forbes, 1892 – New Zealand musk duck – previously endemic to New Zealand, and occurrin ...

''.

Description

The black-headed duck is the most basal living member of its subfamily, and it lacks the stiff tail and swollen bill of its relatives. Overall much resembling a fairly typical diving duck, its plumage and other peculiarities indicate it may not be a very close relative of the other stiff-tailed ducks, but rather the product of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

from the ancestors of the stiff-tailed ducks. The black-headed duck is about long. Males weigh an average of about and females . The species has a distinctive shape, with a long body and disproportionately short wings. Its bill has a black

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

and an orange

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

; the maxilla has a rosy patch at its base during the breeding season. Adult males have a glossy black head and upper neck and a white chin. Their upperparts are deep brownish black with cinnamon or pale rufous speckles and

vermiculation Vermiculation is a surface pattern of dense but irregular lines, so called from the Latin ''vermiculus'' meaning "little worm" because the shapes resemble worms, worm-casts, or worm tracks in mud or wet sand. The word may be used in a number of ...

. The folded wing shows two white bars. Their underparts are whitish with brown mottling and appear silvery. Adult females have a dark brown head and neck and a whitish throat, and are otherwise like the male. Immature birds are similar to the female but have more rufous upperparts, more yellowish underparts, and a pale eye stripe.Lowther, P. E. (2020). Black-headed Duck (''Heteronetta atricapilla''), version 1.0. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blhduc1.01 retrieved November 30, 2022

Distribution and habitat

The black-headed duck has two separate ranges. One is the western side of central Chile. The other is from extreme southern Bolivia south through central Paraguay to central Argentina and east through southern Uruguay into southernmost Brazil. Undocumented sight records in the

Falkland Islands The Falkland Islands (; es, Islas Malvinas, link=no ) is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and about from Cape Dubouze ...

lead the South American Classification Committee of the

American Ornithological Society The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its m ...

to treat it as hypothetical there. It mostly inhabits freshwater marshes whose dominant plant is the sedge '' Scirpus californicus'', and outside the breeding season may be found in lakes, water-filled ditches, and sometimes flooded fields.

Behavior

Movement

The black-headed duck is partially migratory. It is a year-round resident in most of its range but is found in most of Paraguay and its small Bolivian range only in the non-breeding season.

Feeding

The black-headed duck feeds by diving. Though little information is available about its diet, a major component appears to be seeds of ''Scirpus californicus'', and snails a minor component.

Breeding

The black-headed duck is unique among waterfowl; it is an obligate

brood parasite Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were it ...

. The female does not build a nest but lays it's eggs in the nests of other birds. Known hosts include the

rosy-billed pochard The rosy-billed pochard (''Netta peposaca''), alternatively named rosybill or rosybill pochard, is a member of family Anatidae. Though classified as a diving duck, this pochard feeds more like a dabbling duck feeding on seeds roots, sedges, aqua ...

(''Netta peposaca''), the red-fronted coot (''Fulica rufifrons''), and the

red-gartered coot The red-gartered coot (''Fulica armillata'') is a species of bird in subfamily Rallinae of family Rallidae, the rails, gallinules, and coots. It is found in Argentina, Brazil, Chile, Paraguay, and Uruguay.HBW and BirdLife International (2021) H ...

(''F. armillata''). At least 18 other species have been reported as hosts, including several other waterfowl and rail/coot species, the brown-hooded gull (''Chroicocephalus maculipennis''), and a few raptors. Unlike some

cuckoo Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes . The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals and anis. The coucals and anis are sometimes separ ...

s, neither the chicks nor adults destroy the eggs or kill the chicks of the host. In contrast with brood parasitic

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...

s, whose young are

altricial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...

, black-headed duck ducklings are

precocial In biology, altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. Precocial species are those in which the young are relatively mature and mobile from the mome ...

. After an incubation of about 25 days, the ducklings are completely independent a few hours after hatching and leave the nest.

Vocalization

The black-headed duck is usually silent. It does give a low "''quah quah''" as part of a courtship display, and also "a two note grunt followed by a whistle: – ''gr-rump-freet''." Females make "clucking notes."

Status

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed the black-headed duck as being of Least Concern. It has a large range, and though its population size is not known it is believed to be stable. No immeditate threats have been identified. It may be "impacted by changes in available habitat."

References

External links

*David Attenborough, /www.youtube.com/watch?v=4Mb0GOITRUU Nature of the Cuckoo Duck The Life of Birds, BBC Episode 9, 19 minutes ff. * * {{Taxonbar, from=Q596050 black-headed duck Brood parasites Birds of Chile Birds of Argentina Birds of Uruguay black-headed duck