Valmiki Tiger Reserve forms the easternmost limit of the Himalayan Terai forests in India and is the only tiger reserve of Bihar. Situated in the Gangetic plains, the forest has a combination of bhabar and terai tracts. Valmiki Tiger Reserve lies in the north-western (mostly in the West Champaran) district of Bihar. Name of the district has been derived from two words Champa and Aranya, meaning Forest of Champa trees.

The sanctuary is reported to shelter 250 species of birds, 53 mammals, 145 birds, 26 reptiles and 13 amphibians.