Koshi Tappu Wildlife Reserve lies on the flood plain of the Sapta-Koshi in Saptri and Sunsari Districts of eastern Nepal. The eastern and western embankments of the river define the area. Koshi Tappu Reserve, gazetted in 1976, was established mainly to preserve habitat for the remaining population of wild buffalo in Nepal. The region of Nepal experiences three distinct seasons. Summer lasting from February through May is intensely hot with minimal precipitation. Shade temperatures can reach 40o c. The monsoon commences late May or early June with frequent and violent thunderstorms. Rainfall is greatest during July but high humidity and temperatures are experienced throughout the season. Winter lasts from October through January with unclouded skies and moderate temperatures.

Koshi Tappu is a rectangular shaped reserve, approximately 10 km wide and 10km long, stretching northward form the Nepal/India border along the Sapta-Koshi River. The Sapta Koshi is one of the three main tributaries of the Ganges. Because of its destructiveness during monsoon floods and attempt has been made to control the waters by constructing 7-10 m high embankments parallel to the river. These prevent lateral spread of the enormous monsoon flow. Control gates at the Koshi Barrage on the border with India act as a dam and also contain the river. Rapid and complete inundation of the reserve to depths ranging from 10 to 300 cm. occurs during the monsoon. The river also changes its main course from one season to another.

The vegetation is mainly tall khar-pater grassland with a few pater grasslands with a few patches of khair-sissoo forest and deciduous mixed riverine forest. The reserve offers important habitat for a variety of wildlife. The last surviving populations, (about 100 individuals) of wild buffalo or arna (Bubalus arnee arnee) are found here. They are distinguished from domestic animals by their much bigger horns. Other mammals occurring here are hog deer, wild boar, spotted deer, and blue bull. The reserve also assists the local economy be providing fishing permits and allowing the collection of edible fruits and ferns in season.

A total of 280 different species of birds have been recorded in the reserve. These include twenty species of ducks, two species of ibises, many storks, egrets, herons and the endangered swamp partridge and Bengal florican. The Koshi Barrage is extremely important as a resting place for migratory birds and many species recorded there are not seen elsewhere in Nepal. The endangered Gharial crocodile and Gangetic dolphin have been recorded in the Koshi River. Local villagers are permitted to collect grasses from within the reserve in January each year. These are used for thatching roofs and building house walls. Because of intensive agriculture the grasses can no longer be found outside the reserve. An estimated us $ 250.00 worth thatch grass was removed during January 1987.

The best time to visit Koshi Tappu is between October and March when many migratory and resident birds can be seen at the barrage and on the main river channel. Several Himalayan peaks, including Makalu (8475 m) the world’s fifth highest mountain, can be seen during this period of cooler clear weather. The trail along the eastern embankment of a the reserve provides places to observe birds, and at dusk and dawn some of the resident animals. The government Hattisar (elephant stable) at Koshi Tappu has the distinction of biding one of the few facilities in Asia where elephants breed regularly. His Majesty's Government maintains eight female elephants. A semi-wild male, named Ganesh Maharaj by locals, frequently visit and mates with the females, producing a total of nine youngsters so far. Local people consider Ganesh Maharaj, named after the Hindu God, sacred. Visitors can arrange elephant ride into the reserve from the Reserve Headquarters. Baraha Chhetra, located 5 km north of Chatara, is the site of an annual religious festival and is sacred to both Hindus and Buddhists.