Anser melanotos Pennant, 1769, Ceylon. Two subspecies.
OTHER COMMON NAMES
English: Knob-billed duck, black-backed goose; French: Canard-а-bosse bronzй; German: Glanzente; Spanish: Pato Crestudo.
22.1–29.9 in (56–76 cm); 2.7–5.8 lb (1.23–2.61 kg); males have a prominent black fleshy crest on upper bill.
S. m. melanotos: Africa south of Sahara and Madagascar; from Pakistan through tropical India to southern China. S. m. sylvicola: eastern Panama, western Ecuador, eastern Colombia east through Guyana and south to northern Argentina and Uruguay; occasionally Trinidad.
Open swamps, rivers, and lakes with sparse trees.
Very sociable. Males defend 17.3 acres (7 ha) large territories, threatening intruders with wing flap display. Female/ female aggression common while searching for nest cavities.
FEEDING ECOLOGY AND DIET
Vegetarian, but also feeds on some invertebrates. Grazes on land; swims, dabbles, and wades in shallow water.
Seasonally monogamous, but sometimes polygynous. Forced copulations are common. Breeding season depends very much on the local rainy season. Nests in tree cavities or occasionally on ground. Lays 6–20 eggs; incubation c. 28–30 days; fledging c. 10 weeks.
Listed on Appendix II of CITES. South American subspecies is uncommon and threatened by deforestation, hunting, and poisoning by rice farmers. African and Asian populations are not threatened.
SIGNIFICANCE TO HUMANS
Considered a pest by rice farmers. Hunted for food.
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