By Joseph Boss
Geographic Range
Heteronetta atricapilla is found in South America in southern Brazil, Chile, and Argentina. Heteronetta atricapilla is a partially migratory species. Northern breeding populations are sedentary, while southern breeding populations migrate north during the austral winter. These southern populations migrate into Bolivia, southern Brazil, and Uruguay. (International Union for Conservation of Nature and Natural Resources, 2004; Mongabay.com, 2006)
Biogeographic Regions:
neotropical 
(native ).
Habitat
Black-headed ducks are found in marshes, bogs, swamps, fens, peatlands, and permanent freshwater lakes. Black-headed ducks are found in terrestrial environments and semipermanent marshes containing a large amount of plant life. (Mongabay.com, 2006)
These animals are found in the following types of habitat:
tropical ; terrestrial ; saltwater or marine ; freshwater .
Aquatic Biomes:
lakes and ponds; coastal .
Physical Description
(15.28 to 22.18 oz; avg. 18.97 oz)
(13.78 to 15.75 in)
Black-headed ducks are blackish-brown on their breast and underside, with black heads, wings, and backs. The upper mandible is black with a yellow edge and the lower mandible is dark yellow. Black-headed ducks have dark grey legs with yellowish-green shading along the tarsi. Adult females are larger than males. Wings of adults are flecked with small, white spots or they are solid grey-brown. Juvenile ducks are distinguished from adults by having a lighter colored vertical line above the eye, extending from the eye to the crown. (Answers Corporation, 2006; Hohn, 1975; Weller, 1967)
Black-headed ducks moult twice each year. In August and September birds moult into their nuptial plumage. In December and January the nuptial plumage replaces the winter (non-nuptial) plumage. (Weller, 1968)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: female larger.
Reproduction
Black-headed ducks breed twice yearly.
Black-headed ducks breed in fall and spring.
During courtship, males stretch their neck by inflating the bilateral cheek pouches and the upper esophagus in order to attract female mates. Black-headed ducks are promiscuous, with both males and females taking multiple mates during the breeding season. (Hohn, 1975)
Mating systems:
polygynandrous (promiscuous) .
Black-headed ducks are brood parasites. Females lay their eggs in the nests of other species. Black-headed ducks deposits their eggs in nests around 1 meter above the water and lay 2 eggs, on average, per nest. Egg survival rate is around a third of the total number of eggs laid. Black-headed ducks breed twice a year, in fall and spring. (Answers Corporation, 2006; Hohn, 1975; Rees and Hillgarth, 1984)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
Black-headed ducks do not build nests or incubate their eggs; instead they are brood parasites and rely on other duck species for these tasks. Black-headed duck adults and newborn chicks do not harm the eggs or chicks of the host species. The eggs are incubated for approximately 21 days by their hosts. A few hours after hatching, black-headed duck chicks are capable of walking and feeding on their own. (Answers Corporation, 2006; Rees and Hillgarth, 1984)
Parental investment:
no parental involvement; precocial ; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female).
Lifespan/Longevity
Specific information on black-headed duck lifespan and longevity was not available. However, survival of other members of the family Anatidae is variable. From 65 to 80% of ducklings die in their first year. After this crucial year, survival rate increases. Most birds that reach adulthood live for only another 1 to 2 years. The maximum recorded lifespan within the family Anatidae is 28 years. (Chanticleer Press and Inc., 2001)
Behavior
Black-headed ducks are migratory, flying in flocks of up to 40 birds. Black-headed ducks feed mostly in early morning, rest on land in the daytime, and swim mostly during the evening. During the evening male and female black-headed ducks patrol nearby nest sites searching for suitable hosts. Preferred host nests are coots, since their nests are common in marshy areas. (Rees and Hillgarth, 1984; Weller, 1968)
Home Range
Since black-headed ducks do not make nests, they are not territorial. They move throughout a large range in order to search for host nests and do not stay within any particular home range. (Rees and Hillgarth, 1984; Weller, 1968)
Communication and Perception
Male black-headed ducks communicate with potential mates by stretching their necks, they also use vocalizations to some extent. (Hohn, 1975)
Food Habits
Black-headed ducks feed mostly in the morning by diving, head-dipping, dabbling, and mud-filtering. Black-headed ducks eat mostly plant material, such as seeds, underground tubers, green herbaceous foliage of aquatic grasses and sedges, sea grasses, and submerged pond weeds. They may also eat some aquatic invertebrates. (Answers Corporation, 2006; Chanticleer Press and Inc., 2001; Rees and Hillgarth, 1984)
Animal Foods:
insects; aquatic crustaceans.
Plant Foods:
leaves; roots and tubers; seeds, grains, and nuts.
Predation
- host duck species, mostly pochards (Netta)
- coots (Fulica)
- humans (Homo sapiens)
- raptors (Falconiformes)
The main predators of black-headed duck young are other ducks whose nests have been parasitized by black-headed ducks. Almost half of their eggs die because host ducks recognize the eggs and destroy them. Black-headed duck eggs are not camouflaged; they are white and quite conspicuous. Black-headed ducks are hunted by humans for food and plumage. Adults may also be preyed on by large predators such as raptors. Their dark feather color and patterning helps to camouflage them in wetland vegetation. (Answers Corporation, 2006; Weller, 1968)
Anti-predator adaptations::
cryptic .
Ecosystem Roles
Black-headed ducks are brood parasites, they rely on other duck species to incubate and provide shelter for their eggs. This negatively affects the hosts since the host species must allocate energy to hatch the foreign eggs, which may result in a lower number of their own eggs hatching and their own hatchlings surviving to adulthood. (Answers Corporation, 2006)
Key ways these animals impact their ecosystem:
parasite .
- rosy-billed pochards (Netta peposaca)
- coots (Fulica)
- other pochards (Netta)
Economic Importance for Humans: Negative
There are no known adverse effects of black-headed ducks on humans.
Economic Importance for Humans: Positive
Humans hunt black-headed ducks for food and for use of their plumage. (Answers Corporation, 2006)
Ways that people benefit from these animals:
food ; body parts are source of valuable material.
Conservation Status
IUCN Red List: [link]:
Least Concern.
US Migratory Bird Act: [link]:
No special status.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special status.
Black-headed ducks are not currently considered at risk, but may be threatened by habitat loss, hunting, and pollution. (Answers Corporation, 2006)
For More Information
Find Heteronetta atricapilla information at
Contributors
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
Joseph Boss (author), Kalamazoo College. Ann Fraser (editor, instructor), Kalamazoo College.
