Merganetta armata

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.

• Biogeographic Regions
• neotropical neotropical
  • native native

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.

• Habitat Regions
• tropical tropical
• freshwater freshwater

• Terrestrial Biomes
• mountains mountains

• Aquatic Biomes
• rivers and streams

• Other Habitat Features
• riparian riparian

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful

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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

• Parental Investment
• precocial 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.

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.

• Key Behaviors
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social

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.

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.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods

• 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.

Ecosystem Roles

Torrent ducks impact populations of invertebrate larvae through predation.

Economic Importance for Humans: Positive

Torrent ducks are hunted and eaten by humans.

• Positive Impacts
• food food
• ecotourism ecotourism

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.

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.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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. 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.

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

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 .

1985. Duck. Pp. 157-161 in A Dictionary of Birds . Great Britain: The British Ornitholigists' Union.

1990. Merganetta armata Merganetta armata. Pp. 33 in Distribtion and Taxonomy of Birds of the World . New haven: Yale University Press.

2003. Torrent Duck. Pp. 382-383 in 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 The Illustrated Encyclopedia of Birds: The Definitive Reference to Birds of the World , Vol. N/A, N/A Edition. New York: Prentice Hall Press.