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Merganetta armatatorrent duck

By Jenica Lee

Geographic Range

Torrent ducks are native to the mountains of Colombia and the Santa Marta mountains of the Andes. They can also be found along the west coasts of Venezuela, Ecuador, Chile, Peru, Bolivia and Argentina. ("Duck", 1985; "Merganetta armata Merganetta armata", 1990; "Torrent Duck:Merganetta armata", 1990; Howard and Moore, 1991)

Habitat

Torrent ducks live in areas of some of the most powerful and fast flowing rivers in the Andes, which are surrounded by rigid and steep mountain slopes. Water that flows from the ice capped mountains runs off creating waterfalls and rivers, where torrent ducks live and thrive. (Koepcke, 1970; "Merganetta armata Merganetta armata", 1990; "Torrent Duck", 2003; "Torrent Duck:Merganetta armata", 1990; Koepcke, 1970; Todd, 1996)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    300 to 4600 m
    984.25 to 15091.86 ft

Physical Description

Torrent ducks have an aerodynamic and sleek body, extremely powerful legs, a strong tail, and durable long claws, all of which are well adapted for the turbulent habitat in which they live. Torrent ducks are sexually dimorphic. Males have a white head and neck with a black stripe across the eye and down the back. They also have a dark under body with dark and green iridescent wings with spurs used for fighting. Southern sub-species have a darker ventral side and lighter dorsal side, while northern sub-species are white on the ventral side and have a darker dorsal side. Female torrent ducks have a gray head and neck. The body of females is mostly black with gray lined feathers and a cinnamon red under body. The wings are black with smaller spurs than males and the tail is white with black stripes. Torrent ducks have a distinctive, bright red bill, which is long, narrow, soft and jagged, making it perfect for scavenging under rocks for bottom-dwelling larvae. ("Duck", 1985; "Torrent Duck", 2003; "Torrent Duck:Merganetta armata", 1990; Baldassarre and Bolen, 1994; Howard and Moore, 1991; Humphrey, et al., 1970; Johnsgard, 1965; Johnsgard, 1968; Koepcke, 1970; Merne, 1974; Todd, 1996)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    315 to 481 g
    11.10 to 16.95 oz
  • Range length
    43 to 46 cm
    16.93 to 18.11 in

Reproduction

Male torrent ducks are adorned with elaborately patterned plumage to attract females. During courtship, male torrent ducks use distinct postures as part of courtship. They will repetitively bow, rapidly flap their wings and kick up water with their legs. Courtship also includes vocal communication between males and females. It is common for a male and female bird to swim around each other, rising out of the water and snapping at one another during courtship. Once a partner is found, the two torrent ducks are monogamous for life. ("Torrent Duck:Merganetta armata", 1990; Johnsgard, 1965; Johnsgard, 1968; Todd, 1996)

Depending on the sub-species, the reproductive cycles of torrent ducks vary. In the Colombian species (M. armata colombiana) eggs are laid as early as February, whereas the Ecuadorian subspecies (M. armata leucogenis) lay their eggs in April, and the rest of the southern subspecies lay their eggs in late September and early October. Nests are well hidden and created in deep crevices alongside rivers, in anything from a hollow tree to an abandoned cave. Nests can be anywhere between nine and sixty feet on a cliff above the river. The white eggs are large in proportion to females; the clutch can weigh up to half the body weight of the mother duck. The long incubation period is essential to ensure development for young ducklings to be able to swim and survive the harsh waters of their environment. (Johnsgard, 1968; Johnson and Moffett, 1972; Todd, 1996)

  • Breeding interval
    Torrent ducks breed once yearly.
  • Breeding season
    Torrent ducks breed from February to October, depending on geographical location.
  • Range eggs per season
    2 to 5
  • Average eggs per season
    3
  • Average time to hatching
    43.5 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Both male and female torrent ducks care for their offspring. Males don't incubate eggs, but females will not return to a nest for incubation unless the male is present. The male assists the female in protecting and caring for the young. Immediately after hatching, the young take on the dangerous currents of the mountain rivers in which they live. Males and females remain close to the young. Females fly down to the turbulent waters below the nest and insistently call the ducklings. Ducklings plunge from their cliff nests into the water below. It is not uncommon for the ducklings to propel off of rocks and vegetation on the side of the cliffs before reaching the bottom. They are not harmed by this, partially because they are so small (only 35 grams) and heavily wrapped in down, which slows down their fall from the nest and also cushions their landing. The parents aid the ducklings in order to guide them through the dangerous water, keeping the newly hatched ducklings between themselves and the bank. The ducklings are immediately able to swim in these fast currents. If a duckling is swept downstream by the current, both parents chase after it to save it. (Johnsgard, 1968; Johnson and Moffett, 1972; Todd, 1996)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

Torrent ducks are difficult to rear in captivity. The longest living torrent duck in captivity was a single 18 year old female. Lifespan in the wild is not well understood. (Todd, 1996)

  • Range lifespan
    Status: captivity
    18 (high) years

Behavior

Torrent ducks are strong swimmers and divers, and thus rely mostly on transportation through swimming, with little emphasis on flying for mobility. These ducks fly one to several meters above the surface of the river to get from one part of the river to another. They swim using their large, powerful feet and they nod their heads while swimming. Their small bodies allow them to rapidly scale waterfalls. Their long, powerful claws are perfectly adapted to clinging to slippery rocks. Their strong tails are used for steering and diving as well as for balancing on steep and slippery rocks in the middle of the rivers. Torrent ducks are cautious animals and swim with most of their bodies submerged when frightened, to avoid detection. Torrent ducks groom their feathers almost constantly to maintain their waterproof qualities. ("Torrent Duck:Merganetta armata", 1990; Johnsgard, 1968; Johnsgard, 1992; Merne, 1974; Todd, 1996)

  • Range territory size
    8 to 16 m^2

Home Range

A pair of torrent ducks will occupy a variable length of river, depending on the abundance of resources in that area. Torrent ducks are territorial and vocal, males use the long spurs on their legs to ward off invaders. (Baldassarre and Bolen, 1994; Todd, 1996)

Communication and Perception

Male and female torrent ducks differ in the type of sounds they make. To communicate, the male call is a high pitched whistle in one single tone, which can be heard over the turbulent river water. The female has a deeper, booming call, much like a squabble or quacking. Male and female ducks usually communicate to their mate and with their young, and as a territorial warning signal to either neighbors or intruders. A whistling noise is also created by these ducks when they are taking off or landing. (Johnsgard, 1968; Merne, 1974; Todd, 1996)

Food Habits

Torrent ducks use their sleek lined body to dive into fast flowing rivers to catch insect prey such as stonefly larvae, mayfly larvae, caddisfly larvae, and other larvae, small fish, mollusks, crustaceans, and other aquatic invertebrates. Torrent ducks may also wait underneath a powerful waterfall to catch prey. Torrent ducks use several techniques to bring food from different depths of the river, including kicking it up with their feet. They will also scavenge and wade in the more shallow areas of the river in eddies and underneath rocks. A wide and shallow stretch of river will produce the most abundant amount of resources for the ducks. Young ducklings are believed to have the same diet as their parents. ("Torrent Duck", 2003; "Torrent Duck:Merganetta armata", 1990; Johnsgard, 1992; Todd, 1996)

  • Animal Foods
  • fish
  • insects
  • mollusks
  • terrestrial worms
  • aquatic crustaceans

Predation

Humans sometimes hunt torrent ducks. Otherwise, little is known about natural predators of torrent ducks. It is likely that most predation is on the young hatchlings once they've left the nest. Torrent ducks live in a habitat that is challenging to navigate for most animals and they construct nests in inaccessible places. It is possible that most predation on young torrent ducks is by large fish. (Todd, 1996)

Ecosystem Roles

Torrent ducks impact populations of invertebrate larvae through predation.

Economic Importance for Humans: Positive

Torrent ducks are hunted and eaten by humans. ("Torrent Duck:Merganetta armata", 1990)

Economic Importance for Humans: Negative

There are no negative effects of torrent ducks on humans.

Conservation Status

Torrent ducks have a fairly stable population and tend to inhabit large areas of inaccessible terrain that acts as natural protection. However, torrent ducks are sensitive to habitat changes such as pollution, pesticide contamination hydroelectric dam construction, and introduced species of trout (Salmo trutta, Salvelinus fontinalis, Oncorhynchus mykiss, and other Salmo and Oncorhynchus species) that compete for food. Torrent ducks once inhabited Isla Grande but no longer do, due to predation by humans. (Humphrey, et al., 1970; Johnsgard, 1968)

Other Comments

Merganetta armata has at least six subspecies, they differ only in their coloration and distribution. The subspecies include: M. a. colombiana, M. a. leucogenis, M. a. turneris, M. a. garleppi, and M. a. berlepschi, all of which are found along the Andean cordillera. Merganetta armata armata, however, inhabits the largest range. (Merne, 1974; Baldassarre and Bolen, 1994; Merne, 1974)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Jenica Lee (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

1985. Duck. Pp. 157-161 in B Campbell, E Lack, eds. A Dictionary of Birds. Great Britain: The British Ornitholigists' Union.

1990. Merganetta armata Merganetta armata. Pp. 33 in C Sibley, B Monroe, Jr, eds. Distribtion and Taxonomy of Birds of the World. New haven: Yale University Press.

2003. Torrent Duck. Pp. 382-383 in J Jackson, W Bock, D Olendorf, eds. Grzimek's Animal Life Encyclopedia, Vol. Volume 8: Birds I, Second Edition. Farmington Hills, MI: Gale Group Inc.

1990. Torrent Duck:Merganetta armata. Pp. 81 in C Perrins, ed. The Illustrated Encyclopedia of Birds: The Definitive Reference to Birds of the World, Vol. N/A, N/A Edition. New York: Prentice Hall Press.

Baldassarre, G., E. Bolen. 1994. Waterfowl Ecology and Management. New York: John Wiley & Sons, Inc.

De Schauensee, R. 1964. The Birds of Colombia and Adjacent areas of South and Central America. Narberth, PA: Livingston Publishing Co.

Howard, R., A. Moore. 1991. A Complete Checklist of the Birds of the World (Second Edition). San Diego: Academic Press.

Humphrey, P., D. Bridge, P. Reynolds, R. Peterson. 1970. Birds of Isla Grande (Tierra del Fuego). Kansas Museum of Natural History: Smithsonian Institution by the University of Kansas Museum of Natural History.

Johnsgard, P. 1968. Waterfowl, Their Biology and Natural History. Lincoln: University of Nebraska Press.

Johnsgard, P. 1992. Ducks in the Wild. Conserving Waterfowl and their Habitats. Schrewsbury, England: Swan Hill Press.

Johnsgard, P. 1965. Handbook to Waterfowl Behavior. New York: Cornell University.

Johnson, A., G. Moffett. 1972. Supplement to The Birds of Chile and Adjacent Regions of Argentina, Bolivia and Peru. Beunos Aires: A.W. Johnson.

Koepcke, M. 1970. Birds of the Department of Lima, Peru. Wynnewood, PA: Livingston Publishing Co.

Merne, O. 1974. Ducks, Geese and Swans. New York: Hamlyn Publishing Group Limited.

N/A, 2006. "IUCN Red List of Threatened Species" (On-line). Accessed November 10, 2006 at http://www.redlist.org.

Owen, M., J. Black. 1990. Waterfowl Ecology. New York: Chapman and Hall.

Ripley, D. 1957. A Paddling of Ducks. City of Washington: Smithsonian Institution Press.

Todd, F. 1996. Natural History of the Waterfowl. Vista, Ca: Ibis Publishing Company.

True, D. N/A. "Torrent Duck, Meganetta armata" (On-line). Sylvan Heights Waterfowl. Accessed October 04, 2006 at www.sylvan-heights.org/torrent_duck.php.

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