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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

n duck in subfamily Oxyurinae of

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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

.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, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

, and

Uruguay Uruguay, officially the Oriental Republic of 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 the Río de la Plata to the south and the A ...

.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 (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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

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 The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of Anatidae, the diverse and very large family that includes ducks, geese, and swans. The diving ...

, 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 comm ...

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 In vertebrates, the maxilla (: maxillae ) 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. The two maxil ...

and an orange

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

; 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. 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 File:Heteronetta atricapilla 117507900.jpg, Male File:Heteronetta atricapilla 250320228.jpg, Female

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 (; ), commonly referred to as The Falklands, 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 from Cape Dub ...

lead the South American Classification Committee of the American Ornithological Society 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 may refer to: Nature * Brood, a collective term for offspring * Brooding, the incubation of bird eggs by their parents * Bee brood, the young of a beehive * Individual broods of North American periodical cicadas: ** Brood X, the largest ...

. The female does not build a nest but lays its eggs in the nests of other birds. Known hosts include the rosy-billed pochard (''Netta peposaca''), the red-fronted coot (''Fulica rufifrons''), and the red-gartered coot (''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 somet ...

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 generally have an anisodactyl arrangement of their ...

s, whose young are

altricial Precocial species in birds and mammals are those in which the young are relatively mature and mobile from the moment of birth or hatching. They are normally nidifugous, meaning that they leave the nest shortly after birth or hatching. Altricial ...

, black-headed duck ducklings are

precocial Precocial species in birds and mammals are those in which the young are relatively mature and mobile from the moment of birth or hatching. They are normally nidifugous, meaning that they leave the nest shortly after birth or hatching. Altricial ...

. 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) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

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 immediate 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 Taxa named by Blasius Merrem