The torrent duck (''Merganetta armata'') is a member of the
duck
Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...
,
goose
A goose (: geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera '' Anser'' (grey geese and white geese) and '' Branta'' (black geese). Some members of the Tadorninae subfamily (e.g., Egy ...
and
swan
Swans are birds of the genus ''Cygnus'' within the family Anatidae. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe (biology) ...
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 ...
. It is the only member of the
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 ...
''Merganetta''. It is placed in the shelduck
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
Tadorninae
The Tadornini is a biological tribe that includes the shelducks and sheldgeese, which is placed in subfamily Anatinae of family Anatinae, which includes the ducks and most duck-like waterfowl such as the geese and swans. It has been treated a ...
after the "
perching duck
The term perching ducks is used colloquially to mean any species of ducks distinguished by their readiness to perch high in trees.
Until the late 20th century, perching ducks meant ''Cairinini'', a tribe of ducks in the duck, goose and swan fam ...
" assemblage to which it was formerly assigned was dissolved because it turned out to be
paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
.
This long
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
is a resident breeder in the
Andes
The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
of
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 ...
, nesting in small waterside caves and other sheltered spots. Like the blue duck, it holds territories on fast-flowing mountain rivers, usually above . It is a powerful swimmer and diver even in white water but is reluctant to fly more than short distances. It is not particularly wary when located.
Male torrent ducks have a striking black and white head and neck pattern and a red bill. In-flight, they show dark wings with green speculum. Females of all subspecies are smaller than the drakes; they have orange underparts and throat, with the head and upperparts grey and a yellower bill. Juveniles are pale grey above and whitish below.
The male's call is a shrill whistle, while the female's is a throatier whistle.
This is a declining species due to competition for its
invertebrate
Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
food from introduced
trout
Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...
, pollution, forest destruction, and damming of mountain rivers for hydroelectric schemes. The
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 ...
an population seems relatively stable, while the more northern ones are more seriously affected. However, the overall population is still large enough to warrant classification as a Species of Least Concern in the IUCN Redlist.
Subspecies
The
subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
taxonomy can be confusing. Males of the southern
nominate subspecies
In biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. ...
''M. a. armata'', the Chilean torrent duck, have grey back and blackish underparts, with a chestnut belly. Males of the slightly smaller northern subspecies, the Colombian torrent duck, ''M. a. colombiana'', are paler underneath, with streaked grey-brown underparts. Males of a third subspecies, the Peruvian torrent duck, ''M. a. leucogenis'', are intermediate but very variable in plumage; some have entirely black underparts (''turneri'' morph). Only males of the Chilean torrent duck have a black 'teardrop' mark beneath the eye. The Peruvian torrent duck is sometimes split into 4 subspecies (''leucogenis'', ''turneri'', ''garleppi'' and ''berlepschi''), but these are more likely simply color variations, as they are not limited to distinct areas.
File:Merganetta armata - Rio Urumamba, Peru -juvenile and female-8.jpg, Juvenile (left) and female Peruvian torrent duck on the
Urubamba River
The Urubamba River or Vilcamayo River (possibly from Quechua ''Willkamayu'', for "sacred river") is a river in Peru. Upstream it is called Vilcanota River (possibly from Aymara ''Willkanuta'', for "house of the sun"). Within the La Convención ...
, Peru
File:Merganetta armata - Rio Urumamba, Peru -male-8.jpg, Male Peruvian torrent duck on the rocky banks of the Urubamba River, Peru
File:MerganettaTurneriSmit.jpg, Male (top) and female Peruvian torrent duck, ''turneri'' morph
File:TorrentDuckM.jpg, Male Chilean torrent duck near
