In autumn and winter, 24 migratory waterfowl species from the north utilise the wetlands of Chitwan National Park, which provide vital staging, roosting, resting, foraging and breeding places. The birds stay for about eight months before returning north in March and April. These birds are indicators of healthy wetlands, and they distribute nutrients through their droppings that increase primary ... [Show full abstract] production of aquatic vegetation and fish. A population census of wetland birds was conducted during January 2014 in Chitwan National Park on the Rapti and Narayani rivers and associated wetlands, including Lami Tal, Tamor Tal, Garud Tal, Devi Tal and marshes and lakes around Temple Tiger. The study found that the Ruddy Shelduck Tadorna ferruginea was the migratory waterfowl with the largest population in these rivers.