Koshi Tappu Wildlife Reserve is an example of one of the finest birding sites in Asia. Koshi Tappu was established as a wildlife reserve in 1976 with an aim to protect the last remaining population of Asiatic Wild Buffaloes in Nepal. The reserve has a total area of 175 sq. km. and is roughly rectangular in shape. The principal habitats in the reserve include: wetlands, grasslands and small patches of riverine forest. To date this is the only Ramsar Site (a wetland of international significance) in Nepal. More than half of Nepal's birds are recorded from Koshi Tappu! Among the mammals, besides Wild Water Buffaloes, the elusive Gangetic Dolphin and Fishing Cat are occasionally seen here.

A barrage on the southern side of the reserve has created a water reservoir where thousands of migrating waders and wildfowl take rest. The barrage was built nearly 40 years ago, mainly to save people in the Indian state of Bihar from the devastating floods of the Koshi River. The Koshi River is bounded by high earthen embankments on both its eastern and western sides which confine the course of the waters within these bunds.

Many small marshlands, pools and grasslands are formed which provide a haven for birds and birdwatchers alike. The vegetation near these banks holds many passerines. In addition, large agricultural fields that lie adjacent to the reserve make fine habitat for many birds. The finest birding sites in and outside the reserves are located between Camp and down south all the way to the barrage. Within this stretch many birds and mammals are found that offer the experience of a lifetime. Koshi Tappu is the ultimate destination for any nature enthusiasts and experts visiting Nepal.