In the terai region of the Shivalik Hills, across the border from Nepal's Chitwan National Park, liesone of the largest forests in Bihar. Spread over an area of 880 sq km, the Valmiki National Park and Wildlife Sanctuary has tigers, leopards, flying foxes, flying squirrels, wild cats, langur, sloth bears, antelopes, 241 species of birds and a variety of reptiles and butterflies. While there were only 10 tigers in the park in 2010, their population has now more than doubled to 22.