Dudhwa National Park, in Lakhimpur-Kheri District of Uttar Pradesh, adjacent to Nepal border, is one of the major projects for wildlife preservation in India. The northern edge of the reserve lies along the Indo-Nepal border and the southern boundary is marked by the river Suheli. 

The forest is in the foot-hills of the Himalyas with the flat land covered by spreads of grasslands, swamps and dense forests of tall 'Sal' trees. Nearly 60 percent of forest is made up of Sal (shorea robusta) trees while the remaining part represents other varieties typical to the sub-Himalayan terrain. This mix of ecosystems plays a key role in sustaining a large number living species. The swamps and vast grasslands with tall, yellow grass provide a natural habitat for tigers, deers, rhino etc while dense forests support a variety of other animals like Leopard, Fishing Cat, Leopard Cat, Wild Elephants, Sloth Bear, Hog Deer, Barking Deer, Swamp Deer, Sambhar Deer,  etc. and 450 species of birds including Swamp Francolin, Bengal Florican and Great Slaty Woodpecker.   

It has two core areas - Dudhwa National Park and Kishanpur wildlife sanctuary and both are 15 km apart with agricultural land between them. The forest of Dudhwa National Park is made up of North Indian Moist Deciduous type. Water bodies in the park attract a number of migratory birds from September till march and the rivers support a rich variety of turtles, crocodiles and fish. Gangetic dolphin is reportedly found in the Geruwa river.