Silent Valley National Park (Core zone: 236.74 square kilometres (91 sq mi)) is located in the Nilgiri Hills, Palakkad District in Kerala, South India. The area in this national park was historically explored in 1847 by the botanist Robert Wight,and is associated with Hindu legend.
Plans for a hydroelectric project that threatened the parks high diversity of wildlife stimulated an environmentalist Social Movement in the 1970s called Save Silent Valley which resulted in cancellation of the project and creation of the park in 1980. The visitors' centre for the park is at Sairandhri.
The area is locally known as "Sairandhrivanam" literally, in Malayalam: Sairandhri's Forest. In local Hindu legend, Sairandhri is Draupadi, the polyandrous wife of the five Pandavas, who disguised herself as Sairandhri, queen Sudeshna's assistant, while they were in exile. The Pandavas, deprived of their kingdom, set out on a 14-year exile. They wandered south, into what is now Kerala, until one day they came upon a magical valley where rolling grasslands met wooded ravines, a deep green river bubbled its course through impenetrable forest, where at dawn and twilight the tiger and elephant would drink together at the water's edge, where all was harmonious and man unknown. Beside that river, in a cave on a hill slope, the Pandavas halted.
The first English investigation of the watersheds of the Silent Valley area was in 1857 by the botanist Robert Wight.The British named the area Silent Valley because of a perceived
absence of noisy Cicadas. Another story attributes the name to the anglicisation of Sairandhri. A third story, refers to the presence there of many Lion-Tailed Macaques Macaca silenus. In 1914 the forest of the Silent Valley area was declared a Reserve Forest, however, from 1927 to 1976 portions of the Silent Valley forest area were subjected to forestry operations. In 1928 the location on the Kunthipuzha River at Sairandhri was identified as an ideal site for electricity generation and in 1958 a study and survey of the area was conducted and a hydroelectric project of 120 MV costing Rs. 17 Crore was proposed by the Kerala State Electricity Board.
Silent Valley is home to the largest population of Lion-tailed Macaque, an endangered species of Primate. Public controversy over their habitat led to establishment of Silent Valley National Park
Silent Valley is rectangular, 7 km (east-west) X 12 km (north-south). Located between 11°03' to 11°13' N latitude and 76°21' to 76°35' E longitude it is separated from the eastern and northern high altitude plateaus of the (Nilgiris Mountains) by high continuous ridges including Sispara Peak (2,206 m) at the north end of the park. The park gradually slopes southward down to the Palakkad plains and to the west it is bounded by irregular ridges. The altitude of the park ranges from 658 m to 2328 m at Anginda Peak, but most of the park lies within the altitude range of 880 m to 1200 m. Soils are blackish and slightly acidic in evergreen forests where there is good accumulation of organic matter. The underlying rock in the area is granite with schists and gneiss, which give rise to the loamy laterite soils on slopes.
The Kuntipuzha River drains the entire 15 km length of the park from north to south into the Bharathapuzha
River. Kuntipuzha River divides the park into a narrow eastern sector
of width 2 kilometers and a wide western sector of 5 kilometers. The
river is characterized by its crystal clear and perennial nature. The
main tributaries
of the river, kunthancholapuzha, Karingathodu, Madrimaranthodu,
Valiaparathodu and Kummaathanthodu originate on the upper slopes of the
eastern side of the valley. The river is uniformly shallow, with no
flood plains or meanders. Its bed falls from 1,861 m to 900 m over a
distance of 12 km, the last 8 km being particularly level with a fall of
only 60 m. Kuntipuzha is one of the less torrential rivers of the
Western Ghats, with
a pesticide-free catchment area.
Silent Valley gets copious amounts of rainfall during the monsoons,
but the actual amount varies within the region due the varied
topography. In general the rainfall is higher at higher altitude and
decreases from the west to east due to the rain shadow
effect. Eighty per cent of the rainfall occurs during the south-west
monsoon between June and September. It also receives significant amount
of rainfall during the north-east monsoon between October and November.
The park being completely enclosed within a ring of hills, has its own micro-climate and probably receives some convectional rainfall, in addition to rain from two monsoons. In the remaining months, condensation on vegetation of mist shrouding the valley is estimated to yield 15 per cent of the total water generated in the rainforest.
In 2006, the Walakkad area of the park received the highest ever annual rainfall of 9,569.6 mm. In 2000, the figure was 7,788 mm; in 2001, 8,351.9 mm; in 2004, 8465.3 mm; and in 2005, 9,347.8 mm. The annual rainfall received in the valley (at Sairandhri?) was 7,788.8 mm in 2000; 8,361.9 mm in 2001. In 2002, 4,262.5 mm; in 2003, 3,499.65 mm; in 2004, 6,521.27 mm, in 2005, 6,919.38 mm; in 2006, 6,845.05 mm; in 2007, 6,009.35 mm; and in 2008 it was 4386.5 mm. The figure till October 2009 was 5,477.4 mm. Average annual rainfall in the park between 2000 and 2008 was thus 6,066 mm.
The mean annual temperature is 20.2 °C. The hottest months are April
and May when the mean temperature is 23 °C and the coolest months are
January and February when the mean temperature is 18 °C. Because of the
high rainfall, the relative humidity is consistently high (above 95%) between June and December.
Valley areas of the park are in a Tropical and subtropical moist broadleaf forests Ecoregion. Hilly areas above 1,000 m are in a South Western Ghats montane rain forests region. Above 1,500 m, the evergreen forests begin to give way to stunted forests, called sholas, interspersed with open grassland. Both are very important to naturalists, biologists and other researchers because the rich biodiversity here has never been disturbed by human settlements. Several threatened species are endemic here. New plant and animal species are often discovered here.
Birdlife International lists 16 bird species in Silent Valley as threatened or restricted: Nilgiri Wood-pigeon, Malabar Parakeet, Malabar Grey Hornbill, White-bellied Treepie, Grey-headed Bulbul, Broad-tailed Grassbird, Rufous Babbler, Wynaad Laughing Thrush, Nilgiri Laughing Thrush, Nilgiri Blue Robin, Black-and-rufous Flycatcher, Nilgiri Flycatcher, White-bellied Blue-flycatcher, Crimson-backed Sunbird and Nilgiri pipit.
Rare bird species found here include Ceylon Frogmouth and Great Indian Hornbill. The 2006 winter bird survey discovered Long-legged Buzzard, a new species of raptor at Sispara, the park's highest peak. The survey found 10 endangered species recorded in the IUCN Red List including the Red winged crested cuckoo, Malabar Pied Hornbill, Pale harrier. The area is home to 15 endemic species including the Black-and-orange Flycatcher.
It recorded 138 species of birds including 17 species that were newly
observed in the Silent Valley area. The most abundant bird was the Black bulbul.
There are at least 34 species of mammals at Silent Valley including the threatened Lion-tailed Macaque, Niligiri Langur, Malabar Giant Squirrel, Nilgiri Tahr, Peshwa’s Bat (Myotis peshwa) and Hairy-winged Bat. There are nine species of bats, rats and mice.
Distribution and demography of all diurnal primates
were studied in Silent Valley National Park and adjacent areas for a
period of three years from 1993 to 1996. Fourteen troops of lion-tailed
macaque, eighty-five troops of Nilgiri langur, fifteen troops of bonnet macaque and seven troops of Hanuman langur
were observed. Of these, the Nilgiri langur was randomly distributed,
whereas the lion-tailed macaque troops were confined to the southern
sector of the Park. Bonnet macaques and Hanuman langurs were occasional
visitors. The Silent Valley forest remains one of the most undisturbed
viable habitats left for the endemic and endangered primates lion-tailed
macaque and Nilgiri langur.
There are at least 730 identified species of insects in the park. The maximum number of species belong to the orders Lepidoptera and Coleoptera. Many unclassified species have been collected and there is a need for further studies.
33 species of crickets and grasshoppers have been recorded of which one was new. 39 species of true bugs (six new) and two species of Homoptera (both new) have been recorded. 128 species of beetles including 10 new species have been recorded.
Over 128 species of butterflies and 400 species of moths live here. A 1993 study found butterflies belonging to 9 families. The families Nymphalidae and Papilionidae contained the maximum number of species. 13 species were endemic to South India, including 5 species having protected status. 7 species of Butterflies were observed migrating in a mixed swarm of thousands of butterflies towards the Silent Valley National Park. In one instance an observer noted several birds attempting to catch these butterflies. The bird species included the Pied Bushchat Saxicola caprata, Nilgiri Pipit Anthus nilghiriensis, Tickell's Warbler Phylloscopus affinis, Greenish Leaf-Warbler Phylloscopus trochiloides and the Oriental White-eye Zosterops palpebrosa.
At least 500 species of earthworms and leeches have also been identified in the park.
33 species of crickets and grasshoppers have been recorded of which one was new. 39 species of true bugs (six new) and two species of Homoptera (both new) have been recorded. 128 species of beetles including 10 new species have been recorded.
Over 128 species of butterflies and 400 species of moths live here. A 1993 study found butterflies belonging to 9 families. The families Nymphalidae and Papilionidae contained the maximum number of species. 13 species were endemic to South India, including 5 species having protected status. 7 species of Butterflies were observed migrating in a mixed swarm of thousands of butterflies towards the Silent Valley National Park. In one instance an observer noted several birds attempting to catch these butterflies. The bird species included the Pied Bushchat Saxicola caprata, Nilgiri Pipit Anthus nilghiriensis, Tickell's Warbler Phylloscopus affinis, Greenish Leaf-Warbler Phylloscopus trochiloides and the Oriental White-eye Zosterops palpebrosa.
At least 500 species of earthworms and leeches have also been identified in the park.
The flora of the valley include about a 1000 species of flowering plants, 108 species of orchids, 100 ferns and fern allies, 200 liverworts, 75 lichens and about 200 algae. A majority Of these plants are endemic to the Western Ghats.
In addition to facilitating recharge of the aquifer, water retention of the catchment basin and preventing soil erosion, every plant in the park from the smallest one celled algae to the largest tree in the forest has unknown potential for beneficial innovations in biotechnology.
Angiosperm flora currently identified here include 966 species belonging to 134 families and 599 genera. There are 701 Dicotyledons distributed among 113 families and 420 genera. There are 265 Monocotyledons here distributed among 21 families and 139 genera. Families best represented are the Orchids with 108 species including the rare, endemic and highly endangered orchids Ipsea malabarica, Bulbophyllum silentvalliensis and Eria tiagii, Grasses (56), Legumes (55), Rubiaceae (49) and Asters (45). There are many rare, endemic and economically valuable species, such as cardamom Ellettaria cardamomum, black pepper Piper nigrum, yams Dioscorea spp., beans Phaseolus sp., a pest-resistant strain of rice Oryza Pittambi, and 110 plant species of importance in Ayurvedic medicine.Seven new plant species have been recorded from Silent Valley, including in 1996, Impatiens sivarajanii, a new species of Balsaminaceae.
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