Silent Valley National Park Kerala
The core of the Nilgiri Biosphere Reserve is the Silent Valley National Park. Despite its name, the Silent Valley (the clamour of Cicadas is conspicuously absent here) echoes with the sounds of teeming wildlife. The denizens of this sprawling habitat of endangered virgin tropical forests include rare birds, deer and tiger.
Perhaps, nowhere else can one also find such a representative collection of peninsular mammals, over a 100 species of butterflies and 400 species of moths and other fauna like the Ceylon Frog Moth, Great Indian Hornbill, the Nilgiri Laughing Thrush and the Lion-tailed Macaque. The river Kunthi descends from the Nilgiri hills, an altitude of 2000 m above sea level, and traverses the entire length of the valley and rushes down to the plains through the deep forest. The river Kunthi never turns brown and is always crystal clear, perennial and wild.
The evapo-transpiration from these forests is much higher than from any other surfaces. This cools the atmosphere, helps easy condensation of water vapour and thus causes the summer rains. Though smaller in size in comparison to the other national parks in India, what makes it unique is the sylvan environment the region has along with its high altitude peaks and several rivers that run through it.
Located 40 km from Mannarkkad, Silent valley is extremely fragile, a unique preserve of tropical evergreen rain forests, totally undisturbed, lying above the equator and the forest strip which causes the summer rains during June- July in Kerala.
The local name for the park is Sairandhrivanam (the forest in the valley) which is also the last representative of tropical evergreen forests in India. The park which is remote has difficult terrain and is surrounded with Attappadi Reserve Forests in the east, and vested forests of the Palghat and Nilambur divisions in the west and south. In the North, the park is an extension of the Nilgiri Forests. The park which has never had human habitation is in the core area of the Nilgiri Biosphere Reserve.
The fauna here includes around 100 species of butterflies, 400 species of moths, Ceylon Frogmouth, Great Indian Hornbill, the Nilgiri Laughing Thrush, the giant Malabar squirrel, Nilgiri langur, the lion-tailed Macaque, elephant, tiger, leopard, wild bear, nilgai, sambar, pit viper etc. The parks best known primates, the Nilgiri Langur and Lion- tailed macaque are both listed in IUCN's Red List of Threatened Animals.
A valuable reserve of rare plants and herbs including around 966 flowering and over 100 orchids plants are found along with the wide range of animals and birds. This park consist of 10 sq.kms of evergreen forests, 15 sq.kms of semi evergreen forests and 40 sq.kms of leaf shedding forests with a large variety of trees. There are very old trees in the park including a huge hollow tree which can hide at least 12 people in it.