Knob-billed Duck

• The male can weigh twice as much as the female, one of the most marked cases of sexual dimorphism among the ducks.
• The knob on its bill grows and swells in the breeding season.
• It is one of the few ducks that habitually perches in trees.
• It nests mainly in tree hollows, which is unusual among ducks. Several females may share a single nest, in what is known as dump nesting.

Skeleton type

Vertebrate - internal bony skeleton (bird)

Habitat & environment

In Africa it occupies the tropical region from south of the Sahara to roughly the Tropic of Capricorn; also in southern Asia. It frequents wetlands and rice fields, which is where one of its names comes from

Size at birth

Precocial chicks, with greyish-brown down above and a yellowish face and underparts, which fly about ten weeks later

Gestation / incubation

28-30 days of incubation, by the female

Litter / clutch size

7-15 yellowish-white eggs; up to 50 have been counted in communal nests shared by several females

Sources consulted: IUCN Red List (BirdLife International 2014); Wikipedia (Sarkidiornis melanotos); Bernis et al. 1994, Ardeola (nombres castellanos SEO); Pennant 1769; Avibase

Best time: All year round in the tropical wetlands of Africa and southern Asia