Lesser whistling duckDendrocygna javanicaWhere and when to see them

The lesser whistling duck is a warm-brown Asian waterbird with a long neck, rounded head and distinctive whistled calls. Despite its name, it belongs to a distinctive lineage of ducks that often stand upright and perch readily. It is widespread in suitable Thai wetlands, including some urban lakes. Floating vegetation and quiet margins are especially valuable, providing food, daytime shelter and cover for broods of small ducklings.

Size

38-42 cm long

Weight

450-600 g

Lifespan

Not reliably established

Status

Least Concern

These ducks are highly social and may gather in sizeable daytime flocks on banks, islands or floating plants. Feeding often increases around dusk and during the night, although undisturbed birds also feed by day. Pairs may nest in tree cavities or concealed vegetation, depending on available sites. Both parents can accompany the brood, guiding ducklings between sheltered feeding patches and responding closely to nearby threats. They are largely nocturnal or crepuscular feeders, becoming more active at twilight. Whistling ducks are known for perching in trees, a behavior less common in many other duck species.

• Its calls are often heard from flocks flying at dusk.
• It can perch in trees despite its strong association with wetlands.
• Both parents may remain with the ducklings.
• The chestnut rump is a useful feature on a bird seen in flight.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Freshwater ponds, marshes, rice-growing landscapes and shallow lakes with abundant vegetation are typical habitats. Sheltered urban wetlands can also support flocks. It is not principally a marine duck, so coastal visitors usually need to seek freshwater habitat slightly inland. The species can also be found in flooded grasslands, paddy fields, and slow-moving rivers. Its adaptability allows it to thrive in both natural and human-modified aquatic environments across its range.

Seeds, aquatic plants and other vegetable material form much of its food, supplemented by insects, molluscs and small aquatic animals. Birds feed among floating vegetation and in shallow water, taking items from the surface or reaching below it. They often filter small invertebrates from the water and graze on submerged and emergent aquatic plants. Ducklings primarily consume small insects and larvae, growing quickly on this protein-rich diet.

Common name

Lesser whistling duck

Scientific name

Dendrocygna javanica

Animal group

Birds

Size

38-42 cm long

Weight

450-600 g

Lifespan

Not reliably established

Status

Least Concern

Identification

Its small size, chestnut rump and rather plain brown plumage distinguish it from the larger fulvous whistling duck, which has a conspicuous pale rump band. In flight, its slow wingbeats and the absence of a speculum distinguish it from other ducks. Juveniles resemble adults but have duller plumage and less distinct markings.