The Distribution and Behaviour of Lesser Whistling-Duck (Dendrocygna javanica) at Lang Sen Ramsar site in Mekong Delta Vietnam

This study aimed to investigate the distribution, behaviour, potential food, competitor, and potential predator of Lesser Whistling-Duck (Dendrocygna javanica) by direct observations at six sub-zones in the Lang Sen Ramsar site in the south of Vietnam, from September 2021 to August 2022. Two hundred sixty nine (269) individuals of the D. javanica were seen on site mainly in pairs and small flocks. The survey showed that Lesser Whistling-Duck often appears in areas with water lettuce and duckweed at sub-zone 9, wild rice and lotus fields at sub-zone 12, and low water level fluctuation at sub-zone 5 in the early morning and late afternoon. The food source of Lesser Whistling-Duck in the reserve Lang Sen are mainly plants (duckweed, water lettuce, young shoots or seeds of lotus, water lily, water hyacinth, and wild rice) and small animals (snail, worm, shrimp, fish, and insect). This bird species is relatively sensitive to environmental influences and their ability to perceive, reflect, and make sound depends on the size of flocks. The carnivores often damage the Lesser Whistling-Duck including black kite, greater coucal, lesser coucal, and python. They are also affected by competition for food and habitat of other waterbirds, activities of tourists, and people around the reserve. The result of observation of Lesser Whistling-Duck is a concern from new area, so it added the information on the distribution of the species, including behaviour, the potential food, competitors, predators, and human threats, which are important in managing the species.