White-winged ducks are among the world’s most endangered birds and are one of the biggest species of duck. In Assamese it is known as ‘Deo Hans’ or spirit duck because of its ghostly call. Its body is black and its head is white and thickly spotted with black, it has conspicuous white patches on its wings and orange or red eyes. The male and female look alike, the male having glossier feathers and being much larger and heavier.
The White-winged duck used to be widely distributed in north-east India, Bangladesh, South East Asia, Java and Sumatra. Now it is extinct in Java. It is found in India only in the northeast, with the main populations in eastern Assam the nearby areas of Arunachal Pradesh. The key protected areas in this country are Dihing-Patkai Wildlife Sanctuary, Dibru-Saikhowa National Park, Namdapha National Park and Nameri National Park. This duck inhabits dense evergreen tropical forests, near swamps and rivers.
White-winged ducks cannot easily be seen in the wild, as they spend their time hidden in trees. They are usually found in pairs or groups of four to six, sometimes more than ten. They love shade and most of the day will find them in secluded jungle pools, sometimes perching on trees during the day. Being crepuscular, they are most active during dusk and dawn. At night their loud calls echo throughout the forest, from a distance, sounding like a ghost. These birds molt annual in September or October, being flightless for a fortnight, when they move into more densely forested swampy areas for protection from predators.
White-winged ducks are monogamous breeders. This means that both sexes have only one partner. Breeding generally seems to depend on the seasonal rainfall, with laying late in the dry season and hatching early in the wet season, which begins in May in the north of their range. In India, February or March is the start of breeding activity and it runs to the end of July. Up to 16 eggs are laid in a nest built in a tree hole, hollow or fork 3 to 12 meters from the ground. Incubation is for 33 days, hatching being timed with the beginning of the heavy seasonal rains. After 14 weeks of being cared for by their parents, the chicks disperse.
White-winged duck populations outside protected areas are thought to be under threat of extinction in 25 years, due to loss of habitat. Drainage of wetland for land, hydropower development, deliberate burning and fragmentation all contribute to this threat. However, even populations within protected areas are threatened, being frequently hunted on account of their good quality meat, as well as suffering from disturbance and contamination of habitat by pollution and pesticides.
According to the IUCN Red List, the total White-winged duck population size is around 350-1,500 individuals, including 250-999 mature individuals. Specific populations have been estimated in these areas: 50 birds in India, around 100 birds in Cambodia and 150 birds in Indonesia. Overall, currently White-winged ducks are classified as Endangered (EN) and their numbers today are decreasing.