Knob-Billed Duck (African Comb Duck)

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Recently, a Knob-Billed Duck, a species generally associated with the wetlands of Rajasthan and Gujarat, was recorded for the first time at Pong Lake Wildlife Sanctuary in Himachal Pradesh. The sighting highlights the ecological importance of Pong Lake as a major habitat for migratory and resident waterbirds.

About Knob-Billed Duck

The Knob-Billed Duck, also known as the African Comb Duck, is one of the largest species of ducks found in the world. It derives its name from the prominent black, leaf-shaped knob (comb) that develops on the bill of the adult male during the breeding season. This distinctive feature makes it easily identifiable among waterfowl.

Its scientific name is Sarkidiornis melanotos, and it belongs to the family Anatidae, which includes ducks, geese, and swans.

Habitat and Distribution

Preferred Habitat

The Knob-Billed Duck inhabits freshwater wetlands, including marshes, swamps, lakes, ponds, floodplains, and slow-moving rivers. It prefers shallow water bodies rich in aquatic vegetation, which provide abundant food and suitable nesting sites.

Unlike many migratory ducks, it is largely a resident species, although it undertakes local seasonal movements during the wet season in search of favourable breeding habitats.

Key Habitat Features

• Freshwater lakes and swamps

• Floodplains and marshes

• Riverine wetlands

• Shallow ponds with aquatic vegetation

Geographical Distribution

The species has a wide tropical distribution across Sub-Saharan Africa, Madagascar, and the Indian subcontinent. Its range extends from Northern India through Nepal, Bangladesh, Myanmar, Laos, and into Southern China.

Within India, it is commonly found in the wetlands of Rajasthan, Gujarat, Madhya Pradesh, Uttar Pradesh, Assam, and several parts of Eastern India.

The recent observation at Pong Lake Wildlife Sanctuary (Himachal Pradesh) represents a significant extension of its known distribution in India.

Physical Characteristics

Size

The Knob-Billed Duck is among the largest duck species, measuring approximately 56–76 cm in length with a wingspan of 116–145 cm. Its body weight generally ranges from 1.03 kg to 2.9 kg.

Appearance

Adult birds possess a white head marked with small dark speckles, while the neck and underparts remain completely white. The upperparts are glossy blue-black with striking greenish and bluish iridescence, especially on the secondary wing feathers.

Sexual Dimorphism

The species exhibits marked sexual dimorphism.

The male is considerably larger than the female and develops the characteristic black knob on the upper bill during the breeding season.

The female lacks this prominent knob and is comparatively smaller in size.

Juvenile Birds

Young birds differ significantly from adults. They possess dull brown upperparts, buff-coloured underparts, and lack the glossy iridescent plumage seen in mature individuals.

Food and Feeding Behaviour

The Knob-Billed Duck is an omnivorous species that feeds on both plant and animal matter.

Its diet consists of aquatic plants, grasses, seeds, grains, insects, molluscs, crustaceans, and other small aquatic organisms.

The bird generally forages in shallow wetlands, where food resources are abundant.

Breeding Behaviour

During the breeding season, the species generally nests in tree cavities, making it unusual among ducks, although ground nests near wetlands are also observed in some regions.

Breeding activity is closely linked to the monsoon season, when wetlands are filled with water and food becomes plentiful.

Conservation Status

According to the International Union for Conservation of Nature (IUCN), the Knob-Billed Duck is classified as Least Concern (LC) because of its wide geographical distribution and relatively stable global population.

However, regional populations are increasingly threatened by wetland destruction, habitat degradation, water pollution, hunting, and the growing impacts of climate change.

Ecological Importance

The Knob-Billed Duck plays an important ecological role by helping maintain the balance of wetland ecosystems. Through feeding on aquatic vegetation and small organisms, it contributes to nutrient cycling and supports the ecological health of freshwater habitats.

Its presence also serves as an indicator of healthy wetlands, making it an important species for biodiversity conservation.

Significance of the Recent Sighting

The first-ever record of the Knob-Billed Duck at Pong Lake Wildlife Sanctuary demonstrates the sanctuary's increasing importance as a critical wetland habitat for diverse bird species.

The sighting also suggests possible changes in bird distribution patterns, which may be influenced by climate change, habitat availability, and changing ecological conditions.