Periyar Wildlife Sanctuary (also known as the Thekkady Wildlife Sanctuary) is one of the finest wildlife sanctuaries in India, and perhaps the finest example of a Tropical Wet-Evergreen forest ecosystem. Located in the scenic surroundings of the Western Ghats hills in the state of Kerala, the Periyar Wildlife Sanctuary covers an area of approximately 777 sq km. The diverse geographical features, such as topography and climate, of Periyar Wildlife Sanctuary support a rich and varied flora and fauna. The terrain of the park is highly undulating and boasts numerous narrow water streams. A 90 km long and high ridge of the Western Ghat forms the northeastern boundary of the Park, separating the states of Kerala and Tamil Nadu.
Periyar National Park chiefly comprises of tropical evergreen forests (30,500ha) and semi-evergreen forests (27,500ha) around the reservoir, and moist-deciduous forests and savanna-woodlands in the central part of the park. In addition, the marshy areas along the fringes of the Periyar Lake are tall grasslands. All these provide both excellent cover, and nourishment in the form of succulent shoots and grasses, making the region one of the richest habitats for large mammals.
The moderate climatic conditions and favorable habitats in and around Periyar National Park support a unique and diverse wildlife. Over 49 species of mammals, 265 species of birds, 36 species of reptiles, 12 species of amphibians, 35 species of fishes and 160 species of butterflies have been identified in Periyar National Park so far. The major wildlife found in Periyar National Park includes Asian Elephants, Tigers, Gaurs, Bonnet Macaque, Leopards, Mouse Deer, Indian Porcupine, Small Indian Civet, Common Palm, Civet, Sambar Deer, Lion-tailed Macaques, Nilgiri Langurs, Wild Boars, Spotted Deer, Barking Deer, Stripe-necked Mongoose, Wild Dogs, Sloth Bears, Malabar Giant Squirrel, Civet, Nilgiri Tahr to name a few. Periyar National Park is also known for its sizable bird population. Over 265 species of birds have already been spotted and identified in the park, enough to attract thousands of ornithologists and bird lovers to the park.
Periyar National Park boasts a quite rich and diverse flora. Around 1,963 species of flowering plants belonging to 823 genera and 159 families have been identified and documented here by the experts of the Kerala Forest Research Institute and Kerala Forest Department. One of the major characteristic plant-communities of the Periyar National Park is the Wet-evergreen Giant Tropical Hill-forest, a climax forest-type found in some moist valleys among the high hills of the Western Ghats. These are dense patches of forest, characterized by continuous high (30m to 50m.) canopy of tropical evergreen trees, with some emergents specimens that may rise even up to 200 feet (60m.) high.