Dudhwa being spread over an expanse of approximately 811 sq km of marshes, grasslands, and dense forests, is an ideal and protected home for over 38 species of mammals, 16 species of reptiles and numerous species of birds.
Tiger, Rhinoceros, Swamp deer, Elephant, Sambar, Hog deer, Cheetal, Kakar, Wild pig, Rhesus monkey, Langur, Sloth bear, Blue bull, Porcupine, Otter, Turtles, Python, Monitor lizard, Mugger, Gharial etc.
Dudhwa is one of the few places in India where as many as five species of deer coexist, including the chital, sambar, muntjac, hog deer and the swamp deer. The swamp deer inside the sanctuary are relatively few in number (about 1,800) and have been relegated to the wetlands. Vast areas that historically supported the species have been left out of the ‘protected area’ and the deer still fall prey to poachers’ guns. Visitors can easily see the expanding herds of the great Indian one-horned rhinoceros Rhinoceros unicornis, the largest and the best known of the three Asiatic species of rhino that was re-introduced from Nepal and Assam.