Between 2013 and 2016 we conducted an inventory and characterization of aquatic avifauna at Lake Tonga, a Ramsar site. We identified 61 species belonging to 17 families, dominated by Anatidae with 14 species. The inventoried species have different phenological status. Some are known for their regular wintering and some for their summer concentrations, while others are residents year round. Population analysis showed the presence of endangered species such as Oxyura leucocephala, Marmaronetta angustirostris and Aythya...