The knob-billed duck (Sarkidiornis melanotos), also known as the African comb duck, is a large, distinctive waterbird famous for the unique, fleshy black lump or "comb" on the bill of the male. It belongs to the family Anatidae and thrives across the tropical and subtropical wetlands of Sub-Saharan Africa, Madagascar, and South Asia.
Physical Characteristics
The Knob: Males possess a large, bulbous black knob on top of their bills, which swells significantly during the breeding season. Females completely lack this feature and have a plain bill.
Plumage: Both sexes exhibit a striking bicolored appearance, with brilliant iridescent purplish-green upperparts and dark wings contrasting against a clean white or buffy breast. Their heads and necks are white with dense black speckles.
Size: They are quite large for ducks, measuring between 56 to 76 cm in length and weighing up to 2.6 kg, with males being substantially larger than females.
Conservation Status
The species is categorized as Least Concern on the IUCN Red List, though global populations face a localized downward trend due to habitat loss and regional hunting pressures. Note that modern taxonomy separates this Old World species from its South American relative, the American comb duck (Sarkidiornis sylvicola), which features entirely black flanks.
Habitat & Behavior
Wetland Specialists: They primarily inhabit freshwater lakes, marshes, swamps, and slow-moving rivers located in open savannas or lightly wooded grasslands.
Tree Perching: Unlike many waterfowl, they are strong fliers and frequently perch in trees to roost and escape land predators.
Diet: They forage by dabbling and grazing on aquatic plants, seeds, agricultural grain, and small aquatic invertebrates.
Vocalizations: They are remarkably quiet birds and are normally completely silent.
The knob on a knob-billed duck (found mostly on males) acts as a sexual ornament. It grows larger during the breeding season. Biologists believe it helps attract mates, shows good health, and signals power against rival males.
Knob-billed ducks mostly eat plants by grazing on land or dabbling in shallow water.
They Eat
Plants and Grasses: Shoots, stems, and aquatic vegetation.
Seeds and Grains: Grass seeds, sedges, and agricultural crops like rice and wheat. They can sometimes become pests for rice farmers.
Animal Matter: Small fish, aquatic insects, insect larvae, locusts, and small water invertebrates.
