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Torrent Duck
Merganetta armata

Torrent Duck
Pato de Torrente
Merganetta armata
Length: 420mm. Sexes unlike. Male: bill red; iris dark brown; head and neck white with black stripes; upper back and scapulars show elongated black feathers with broad white trailing edge, the topmost part of the back is white; lower back, rump and uppertail coverts plumbeous resulting from fine blackish brown and white barring alternatively; tail greyish brown with long and stiff feathers and rachis pale brown. Upper part of breast and top part of flanks black, rest of breast, flanks and abdomen cinnamon chestnut brown striated black on the rachis of feathers; under tail coverts blackish brown mottled cinnamon brown. Wing coverts plumbeous grey, greater wing coverts with narrow white terminal band, primaries greyish brown, secondaries dark metallic green with a hint of gloss on the speculum and narrow white terminal band; axillaries and underwing coverts greyish brown, on bend of wing there is a reddish brown spur with a very sharp point. Legs are dark red with black web.
Female: bill and iris like male; top part of head, lores and hind neck plumbeous grey; auricular patch and sides of neck with fine stripes or bars alternating blackish and whitish giving a greyish appearance; area below ocular and malar region, chin, throat, foreneck, breast, flanks, belly and under tail coverts, rusty cinnamon; upper back and scapulars show black elongated feathers with wide plumbeous grey trailing edge; lower back, rump and uppertail coverts blackish grey and whitish fine strips or bars, giving a plumbeous appearance; rectrices greyish brown with long and stiff feathers, rachis pale brown; wings similar coloration to male and slightly shorter spur; legs like male.
Juveniles: immature show top part of head and neck grey, upper parts similar to female but duller; malar and auricular region, throat and foreneck, breast and belly white; flanks whitish with rusty mottling and blackish barring. In the young male the band on the head and blackish brown on breast are readily distinguished.
Habitat and behaviour: easily identified by its small size and very differentiated coloration in both sexes, its red bill and highly specialised habits, this species is adapted to living exclusively in cold and crystal-clear waters of rushing streams and rivers. Restricted to this aquatic environment without competition, the Torrent Duck has anatomical and morphological traits that set it apart from all other members of the family. Thanks to its slender streamlined body and stiff tail it can move both on the surface and submerged, even with the strongest currents that slide fiercely among the rocks, swimming against or with the current.
Its staple food consists almost exclusively of larvae of aquatic insects that are stuck to stones on the riverbed; to seize them it dives to probe beneath rocks with its thin and soft bill. This duck is found solitary or in small groups; it rests on emergent rocks in the river; when it flies it does so swiftly, low over the water along the winding course of streams and rivers; rather wary and skittish: in the event of danger they jump into the water and swim away, coming ashore by hopping onto a rock. Often silent, occasionally the male utters a whistle-like sound.
The Torrent Duck nests on waterside sheltered spots in holes in trees or in cavities in banks; generally four cream coloured eggs are laid at intervals; once the laying is complete, the female incubates for about thirty days until chicks hatch; the male remains nearby and helps caring for the chicks.
There is record of a nest located in a very wet and dark spot, in which eggs took forty-four days to hatch. Chicks are born usually on the same day and a few hours later they take to the water where the parents await; bearing in mind nests are located rather high above the water, it is surprising chicks go unharmed.
Given its special traits and beauty, the Torrent Duck is unquestionably one of the most interesting species in the family. In El Bolsón, Río Negro, until de 1970s, close to one hundred individuals were counted on the rivers and streams as permanent residents; it is worth noting that the number of males surpassed that of females 10 to 1 or 2. As of the beginning of the 1980s their numbers started to decline; nowadays they are found in inaccessible areas, away from man.
Range: this duck species is widely distributed along the Andean mountain range from Venezuela down to Tierra del Fuego. The species is divided into six races. Out of these, two occur in Argentina: Merganetta armatta berlepschi, in the north from Jujuy to La Rioja; in Patagonia the nominate race (Merganetta armatta armata) is found, from Neuquén to Tierra del Fuego; also in Mendoza and in Chile from the south of Atacama to Magallanes and Chilean Tierra del Fuego.
Illustrated Handbook of the Birds of Patagonia
Kindless: Kovacs Family

Photographs: Mariano Diez Peña

Birding Patagonia • Birdwatcing in Bariloche, Patagonia, Argentina and Chile.
All Rights reserved. Reproduction of photographs is forbidden without permission from the authors.
Photographs on the website: Mariano Diez Peña