Sarkidiornis

A small and unusual group of waterfowl best known for its most prominent member, the knob-billed duck or comb duck (Sarkidiornis melanotos). These ducks are unique among their relatives for their combination of large size, tree-perching behavior, and, most famously, the distinctive fleshy knob on the bills of adult males. Found in both sub-Saharan Africa and parts of South and Southeast Asia, Sarkidiornis is a fascinating genus that bridges the gap between typical dabbling ducks and the more unusual waterfowl that have adapted to life in tropical environments.

A unique behavioral trait in Sarkidiornis ducks is their tree-perching and nesting ability, which is rare among ducks. They are often seen roosting in tall trees near water, and females sometimes nest in tree cavities—again, quite unusual for a duck of their size. Despite being strong swimmers, they are equally at home in open wetlands and seasonal floodplains, where they feed on a mix of aquatic plants, seeds, small invertebrates, and algae. Their feeding style combines dabbling on the water’s surface and grazing in shallow water or moist ground.

In terms of reproduction, Sarkidiornis ducks exhibit polygynous breeding behavior, with one male often mating with several females. During the breeding season, males are more vocal and territorial, using their distinctive knobs as visual signals during displays. Females take sole responsibility for incubating eggs and raising the young, which are able to walk, swim, and feed themselves shortly after hatching.

Though there was once debate over whether African and Asian populations of this duck represented separate species, they are now generally considered subspecies of Sarkidiornis melanotos. This makes Sarkidiornis a monotypic genus, meaning it contains just one recognized living species, although its wide range and distinctive populations have prompted ongoing scientific interest.