Identification:
- Summer: Adult males exhibit a black head and neck with a greenish iridescence. Females have a dark brown head and neck. Eyes are white or pale yellow. The bill is lead-gray with a dark brown or black tip. Legs are yellowish-gray or lead-colored.
Biology and Ecology:
- Prefers to inhabit intertidal zones, inland lakes, and marshes. Nests are constructed in aquatic vegetation along the shorelines.
Distribution:
- Vietnam: Northern plains, Hai Duong province, Ha Tay province (Suoi Hai Lake).
- Global: Amu River basin, Japan, Southern China, Laos, Cambodia, India, Myanmar.
Value:
- A valuable and rare genetic resource with high scientific significance.
Status:
- The population has severely declined. In the winter of 1992, two individuals of this species were observed foraging with a flock of Tufted Ducks and Common Goldeneyes at Suoi Hai Lake (Ha Tay). Six individuals were observed in December 1996 at Xuan Thuy National Park, and as of February 8, 2000, some were found outside the boundaries of Cuc Phuong National Park. The decline is primarily attributed to pollution and disturbance of wetland habitats due to human economic activities.
IUCN Red List:
- Data Deficient (DD)
Conservation Measures:
- Strict prohibition of hunting migratory birds in coastal areas of the Red River Delta. Proper management and sustainable use of large lakes and ponds in the interior. The species migrates to Vietnam during winter, for example, to Suoi Hai Lake (Ha Tay). Listed in the Vietnam Red Data Book (1992, 2000) as “Rare” (R).