The Koshi-Tappu Wildlife Reserve is a protected area in the Terai of eastern Nepal. This reserve was established in the year 2032 B.S. (1975AD.) to conserve and promote the habitat of the wild and water buffaloes (Arna) and to increase their population by protecting the habitat. Koshi Tappu wild life is also recognized both as birdwatchers’ paradise and wetland site from 1987.
This reserve lies on the fold plain of the Koshi River. It has covered the area of 175 sq. km it lies in Sunsari district of Koshi zone and on the island of the Saptakoshi River in Saptari and Udaypur district of Sagarmath zone in the Eastern Development Region. The Sapta Koshi both in the eastern and western side has surrounded this reserve. It ranges from 75 to 81 meters or 246 to 266 ft. in altitude.
The vegetation of the Koshi Tappu Reserve is mainly characterized by mixed deciduous riverine forest, grasslands and marshy vegetation. This reserve consists is about 68 percent grasslands, about 6 percent forest.
Some birds of here are not seen and found other part of Nepal. Koshi Tappu Reserve is an excellent habitat for birds like Swamp Francolin, Black-necked Stork, Lesser Adjutant, Indian Courser, Ruddy Crake, Cotton Pigmy Goose, Baer’s Pochard, Greater Painted Snipe, Pheasant-tailed jacana, Yellow-wattled Lapwing, Imperial Eagle, White-tailed Eagle, Lesser Kestrel, Black-bellied Tern, Bristle Grassbird, Bailon’s Crake, Striated Grassbird etc. Generally, there are about 514 species of bird variety recorded in this reserve.
The reserve has Sesum and Khayaer and Kharpatar grass jungle. Some of them come by flying from Siberia during winter. Different species of ducks live here. Different kinds of Ducks, Comb Duck, Falcated Duck, Spot-billed Duck, herons, storks egrets, ibis can be found and seen on the River bank of this reserve. The 31 different types of species of mammals are recorded like Asian elephant, wild buffalo, spotted deer, jackal, wild boar, hog deer and blue bull (laguna) are found in this reserve. Gaur, Blue Bull, Wile Asian Water Buffalo (Arna) has declined in numbers.
Similiary, two types of Lalsar, many other species of birds such as cranes, storks, egrets, herons and other aquatic birds live in this reserve. Among the aquatic animals, Gharial crocodiles, endangered Gangetic dolphin and alligators are other attractions. About 200 species of fish have been found here in its water courses and ponds. Two types of toad species, nine types of frog species, six types of lizard species, five different types of snake species, and 11 different types of turtle species are recorded in this reserve.
The best time to visit Koshi Tappu Reserve is between Octobers to April.