The Koshi Tappu Reserve, covering an area of about 175 sq. km., is home to the last surviving population of wild buffalo or Arna. There are also many other mammals and birds who find a refuge in this vast reserve. This Reserve was initially founded in 1976 with the objective of protecting the grasslands near the Sapta Koshi River. The reserve is now home to various birds and animals. The increase in the wildlife here has attracted tourists and ornithologists by flocks. The endangered Gharial crocodile and Gangetic Dolphin have been flourishing in the Koshi River. Rare birds like the Bengal florican and Sarus Crane and more than 400 species of birds have been recorded here including migratory species from Siberia and Tibet.