The Silent Valley National Park with a core of approximately 89.52 square kilometres is located in the Nilgiri Hills, Palakkad District of Kerala. One of the last undisturbed tracts of the South Western Ghats mountain rain forests and tropical moist evergreen forests in India. Rectangular in shape, the valley is located between 11.03 degree to 11.13 degree N latitude and 76.21 to 76.35 N longitude and is separated from the eastern and northern high altitude plateaus of the Nilgiri Mountains by high continuous ridges. It slopes down gradually southward to the plains of Palakkad and it is bounded by irregular ridges in the west. With the altitude of it ranging from 658 m to 2328 m at Anginda peak most of the park lies within the altitude range of 880m to 1200 m. Blackish and slightly acidic soil is a good accumulation of organic matter. The rock of the area is granite with schists, a type of rock formed of different minerals that breaks naturally into thin flat pieces and gneiss, a type of metamorphic rock formed at high pressure and temperature deep in the ground, which generates the loamy soil of good quality containing sand, clay and decayed vegetable matter with laterite soils on slopes. !!History The area where the National park is located is known in Malayalam as Sairandhri Vanam, Sairandhri’s forest. Sairandri is the name Draupadi, the wife of the Pandavas assumed when she was the assistant to Queen Sudeshna of the Kingdom of Viraat, while they were living incognito during the final year of their exile. The legend says that during their wanderings they came to a breathtakingly beautiful valley where the lush green grass lands met the wooded ravines, where the tigers and elephants drank water together from a green hued river bubbling its course through dense forest. It is believed that the Pandavas stayed here in a cave on a hill slope on the banks of this river. Home to the largest population of the Lion-tailed Macaque, in 1973 Silent Valley became the focal point of environmental debate when the Kerala State Electricity Board decided to implement an hydro electric project there. In 1976 the KSEB announced its plans to build a dam there. In 1983, the then Prime Minister of India, a strong environmentalist and nature lover, decided to abandon the project. The Silent Valley Forests were declared as a national Park on the 15th of November in the same year. On September 7, 1985, the Silent Valley National Park was dedicated to the nation and a memorial to Indira Gandhi at Sairandhri was unveiled by the late Prime Minister Rajiv Gandhi. The Silent Valley National Park was designated as the core area of the Nilgiri Biosphere Reserve on 1st September 1986 and long term conservation efforts to preserve the Silent Valley eco system has been there since then. The Sairandhri Vanam forests were first explored by an English team led by the Botanist Robert Wight in 1847.The area was named Silent Valley because of a perceived absence of Cicadas, a large insect with transparent wings common in hot countries. Some attribute the origin of the name to the Anglicization of Sairandhri and the third story says the area got its name because of the presence of Lion tailed monkeys whose scientific name is Macaca silenus. !!Rivers The Kunthippuzha River which divides the park into a narrow two kilometres wide eastern sector and to a five kilometres wide western sector runs the entire 15 kilometer length of the park from north to south into the Nila or Bharathappuzha River. The main tributaries of Kuntippuzha, which is of perennial nature and characterized by its crystal clear water, are Kunthancholappuzha, Karingathodu, Madrimaranthodu, Valiaparathodu and Kummathanthodu which originate from the upper slopes of the eastern side of the valley. Kunthippuzha is one of the less torrential rivers of the Western Ghats with a pesticide free catchment area. !!Climate Though Silent valley receives very good rainfall during the monsoon, as the topography of the area is diverse, the actual amount it receives varies. In the Neelikkal area in the west the mean annual rainfall is over 5000mm, while in the eastern side of the park it is around 3200mm.The park, completely enclosed within a ring of hills, has a micro climate of its own. Eighty per cent of the rainfall occurs between the months of June and September during the south-west monsoon and during the north- east monsoon months of October to November also the area gets a significant amount of rainfall. The mean annual temperature is 20.2 degree C and during the hottest months of April and May it is 23 degree C and the temperature during the coolest months of January and February is 18 degree C. The relative humidity is consistently high because of the heavy rain fall. !!Tribes The Mudugar and the Irula tribal people are indigenous to the area and live in the nearby valley of Attappady Reserved Forest. The Kurumbars occupy the highest range outside the park bordering on the Nilgiris. !!Flora and Fauna Situated in the Tropical and subtropical moist broadleaf forests. The evergreen forests begin to give to shoals or stunted forests interfused with vast open grass lands at a height above 1500 metres. The biological data says that about a thousand species of flowering plants, 108 species of orchids, 100 ferns and its allies, 200 liverworts which are flat, branching ribbon shaped plants, the margins of which resemble the lobes of a liver, 75 lichens, and about 200 algae are present here. The researchers are of the opinion that every plant in the area has unknown potential for beneficial innovations in biotechnology. The botanists identified flowering plants here which include 966 species belonging to 134 families and 599 genera. The Ayurvedic experts say that about 110 Ayurvedic medicinal plant species are here. Botanists recorded seven new plant species in Silent valley in recent years including Impatiens sivaranjini, a new species of Balsaminaceae in 1996. In the Silent valley, six different tree associations including three which are restricted to the southern sector, have been identified and described. The central and northern parts of the park are the home to the rest. The flowering of the variety, Cullenia exarillata in the forest is a dominant factor in the occurrence of lion tailed monkeys. A biological study says that all the twelve species of the Silent valley tropical rain forests show good natural regeneration capability. The animal kingdom of the valley includes birds, mammals and insects. The bird most abundantly found is the Black Bulbul. In the valley, 16 bird species are threatened or restricted as per the list of Bird Life International. Rare bird species including Ceylon Frogmouth and great Indian Hornbill are found here. At Sispara, the highest peak of the park, a new species, long-legged Buzzard, was found during the 2006 winter bird survey. Ten endangered species recorded in Red list of the International Union for Conservation of Nature (IUCN), were found during the survey. According to the naturalists, the valley is home to 15 endemic species. The survey recorded 138 species of birds and out them 17 species was newly observed in the Valley. Including the threatened Lion-tailed Macaque, Nilgiri Langur, Malabar Giant Squirrel, Nilgiri Tahr, Peshwa’s Bat and Hairy-winged Bat, there are at least 34 species of mammals at the Silent valley. The forest is one of the most undisturbed habitats left for many endemic and endangered primates. Mammels like the tiger, leopard, leopard cat, jungle cat, fishing cat, Common Palm Civet, Small Indian Civet, Brown Palm Civet, Ruddy Mongoose and Stripe-necked Mongoose are present in the valley. !!Present Challenges Forest fires due to negligence and by people engaged in grazing livestock who often burn an area to get fresh grass shoots during dry seasons are among the major threats facing the forests of Kerala and also the cutting down of hundreds of acres of evergreen tropical forest in the Attappady Hills. Save Silent Valley, a social movement aimed at the protection of the valley was started in 1973. To save one of our precious heritages many steps are being taken by both the Central and Sate Governments. Since the declaration of it as the core area of the Nilgiri Biosphere Reserve by the late Prime Minister Rajiv Gandhi on September 1st 1986, long term conservation efforts have been undertaken to preserve the Silent valley ecosystem. The Kerala Government has formally approved the 147.22 square kilometres Silent valley buffer Zone which is mainly at checking illegal activities in the area and to help long term sustainability of the precious rain forest.