Indian Spot-billed Duck

The Indian spot-billed duck (Anas poecilorhyncha) is a large dabbling duck of the Indian subcontinent and mainland Southeast Asia. Adults are roughly 58–63 cm long, have a wingspan of about 83–95 cm and typically weigh around 0.86–1.07 kg. The plumage is grey-brown with a strongly scaled appearance, while the head and neck are paler.

The black bill ends in a conspicuous yellow tip. The nominate form also shows red spots near the base of the bill, usually strongest in males and sometimes weak or absent in females. White tertials along the side and a green wing speculum broadly bordered with white are also distinctive. Adult males retain broadly similar plumage through the year rather than developing a strongly contrasting non-breeding plumage.

The closely related eastern spot-billed duck (Anas zonorhyncha) is now treated as a separate species in AviList and lacks the red basal bill spots. A mitochondrial-genome study published in 2024 sequenced three Indian spot-billed ducks from Jaipur Zoo in Rajasthan and compared them with closely related Anas lineages. The Indian samples formed a distinct genetic group, while sequences labelled A. poecilorhyncha from China grouped closer to eastern spot-billed duck, and one grouped among mallards. These unexpected placements may reflect the very close relationships within this duck group, hybridisation or misidentification of some archived sequences.

Indian spot-billed ducks use a wide range of freshwater wetlands, including lakes, marshes, ponds, reservoirs, slow rivers, flooded fields and rice paddies. Shallow water with emergent or floating vegetation provides both feeding opportunities and cover for nesting birds and broods.

The species is mainly resident rather than a long-distance migrant, but local movements can be substantial as rainfall, flooding and water levels change. Artificial wetlands and agricultural water bodies can therefore become important habitat where natural wetlands are scarce.

Much of the diet consists of aquatic vegetation, seeds, grain and other plant material. Aquatic invertebrates and other small animal prey are also eaten, especially where they are abundant.

Like other dabbling ducks, the species feeds mainly at or just below the surface by dipping the head and neck underwater or tipping the body forward with the tail raised. Feeding often becomes especially active around dusk and at night, although birds also forage during daylight.

Indian spot-billed ducks are commonly seen in pairs or small groups and may gather into larger flocks outside the breeding period. They spend long periods resting and preening along vegetated wetland margins between feeding bouts and often remain close to cover when undisturbed.

When alarmed they can launch rapidly from the water. Both sexes give calls broadly reminiscent of a mallard, with vocal contact becoming especially noticeable when birds are moving between feeding and resting sites or interacting within groups.

Breeding timing follows rainfall and local wetland conditions and therefore varies across the range. In northern India nesting is often concentrated from July to September or October, while breeding in southern India is often recorded around November and December. The nest is usually a grass-lined cup or scrape hidden in dense vegetation close to water.

Clutches commonly contain about 8–14 eggs. The female performs the incubation, which lasts roughly 24–26 days. The ducklings are precocial: they hatch covered in down and can walk, swim and feed soon after leaving the nest. The female leads and protects the brood while the young grow and develop flight feathers.

The Indian spot-billed duck is classified as least concern on the IUCN Red List and remains widespread across South and Southeast Asia.

State of India's Birds 2025 estimates a long-term national increase of about 44.11%, with an uncertainty interval of 25.41–65.64%. The recent annual estimate is +0.14%, but its interval of −0.86 to +1.15% crosses zero, so there is no clear recent national change. Local populations can nevertheless be affected by wetland drainage, pollution, disturbance, hunting and deterioration of shallow freshwater habitats.