The Yellow-billed Duck is a common and widespread species of dabbling duck, found on or near almost any fresh water habitat, including farm dams, flooded grasslands, slow-flowing rivers and seasonal pans, and sometimes in brackish environments like estuaries. They avoid fast-flowing rivers. These ducks are omnivorous, feeding on terrestrial and aquatic plants, including crops, as well as insects, crustaceans and molluscs. Adults weigh around 1kg.
During the moult (which lasts for about 4 weeks at the end of the summer) or in times of drought they can congregate in flocks of up to 5,000, dispersing again at the onset of the rainy season to then be seen mostly as pairs or in small groups. Yellow-billed Ducks are mostly nocturnal, feeding from dusk to dawn.
Breeding takes place at any time of year, with a peak in summer. Nests are built of plant material lined with down, near to the water and on the ground in dense vegetation. Clutches contain up to twelve eggs. Only the female incubates the eggs and cares for the chicks. The eggs hatch after about a month and the female then leads the ducklings to the water. The ducklings can fly by the time they are two months old.
It is estimated that there are at least 100,000 Yellow-billed Ducks in South Africa, where they commonly occur almost everywhere except in parts of the arid west of the country. The construction of artificial impoundments has certainly benefited this species, aiding an increase both in their range and populations. North of our borders they occur throughout East and Central Africa, and thanks to their wide distribution and large, stable populations are considered of least concern by the IUCN. Hybridization with feral populations of the exotic Mallard is cause for concern however, especially in South Africa.