|Most recent IBA monitoring assessment|
|Year of assessment||Threat score (pressure)||Condition score (state)||Action score (response)|
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Silent Valley is a rectangular tableland enclosed by a high contiguous ridge along its northern and eastern borders, and by a lower, irregular ridge along its western and southern borders. It is flanked by steep escarpments to the south and west, which descend some 1,000 m to the plains of Kerala, and by sheer cliffs to the north and east which rise a further 1,000 m to the Upper Nilgiri Plateau. Kunthipuzha river flows southwards through the entire 15 km length of the Park, dividing it into a narrow western sector of less than 2 km and a wider eastern sector of 5 km. The valley is drained by five main tributaries of the Kunthipuzha, which originate near the eastern border and flow westwards. Only a few minor streams drain into the Kunthipuzha from the western sector. The river is uniformly shallow, with no floodplains. 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. Kunthipuzha is one of the less torrential rivers of the Western Ghats, with a pesticide-free catchment area. The soil is blackish and slightly acidic in the 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 (Anon., undated, 1981, 1982; Unnikrishnan, 1989). The total area is 8,951.65 ha. The Park is contiguous to the proposed Karimpuzha National Park (22,500 ha) in the north and to Mukurthi National Park (7,846 ha), Tamil Nadu, in the northeast. The altitude ranges from 658 m to 2,383 m (Balakrishnan 1984). Most of the Park lies between 880 m and 1,200 m (Anon. undated). High peaks such as Anginda (2,383 m), Sispara (2,206 m) and Kozhipara (1,904 m) occur in the northern part of the Park. Four main types of vegetation can be recognized: Tropical Evergreen Forest, Subtropical Hill Forest, Shola forest and grasslands which are restricted to the narrow sector west of the Kunthipuzha and to the higher slopes and hill tops in the eastern sector. Seven new plant species have been recorded from the Silent Valley (Manilal 1988), as well as many rare, endemic and economically valuable species, such as Cardamom Elettaria cardamomum, Pepper Piper nigrum, Yam Dioscorea spp., various beans Phaseolus spp., a pest-resistant strain of Rice (species unknown), and 110 plant species of importance in Ayurvedic medicine (Nair et al. 1980).
AVIFAUNA: Kerala’s avifauna is well represented within the Park. Two hundred species of birds have been recorded (Jayson 1990, Basheer and Nameer 1990). Four globally threatened species are found here. The Nilgiri Wood-Pigeon Columba elphinstonii is an uncommon bird (Zacharias and Gaston 1999, BirdLife International 2001), even in this well protected forest. The Broadtailed Grassbird Schoenicola platyura has a wide range in the Western Ghats but is uncommon everywhere. Santharam (1996) found it in the Poochipara area in December 1990. The site lies in the Western Ghats Endemic Bird Area (EBA) (Stattersfield et al. 1998). In this IBA, all the 16 endemic or restricted range species have been recorded. Flocks of Wynaad Laughingthrush Garrulax delesserti are sighted up to an elevation of 1,700 m. Above that, it seems to be the range of the Nilgiri Laughingthrush Garrulax cachinnans. Vijayan et al. (1999) also found this species in the upper reaches. Both the species confine themselves strictly to their respective altitudinal ranges. Nilgiri Flycatcher Eumyias albicaudata, a Near Threatened species, is common in the foothills of the National Park. Silent Valley is not only a paradise for local species, but it also host a large number of forest migrants in winter, from the Himalaya and beyond. Some of the forest birds noted are Tickell’s Leaf Warbler Phylloscopus affinis, Large-billed Leaf Warbler Phylloscopus magnirostris, Western Crowned Warbler Phylloscopus occipitalis, Rufous-tailed Flycatcher Muscicapa ruficauda, Brown-breasted Flycatcher Muscicapa muttui and Blueheaded Rock-thrush Monticola cinclorhynchus. This site lies in Biome-10 (Indian Peninsula Tropical Moist Forest) where 15 species are considered as representative of this biome’s assemblage. Nine of these species have been recorded from Silent Valley NP. Only those species which live in comparatively drier habitats are not found here, for example, the Small Greenbilled Malkoha or Blue-faced Malkoha Phaenicophaeus viridirostris, a bird of scrub and secondary jungle, and the Jerdon’s Nightjar Caprimulgus atripennis, a bird found in scrub forests, edges of moist forests and secondary growth. Silent Valley NP has been selected as an IBA as it qualifies three criteria (A1, A2, and A3) and more importantly, it has one of the finest undisturbed forests left in the Western Ghats. This famous forest has significant populations of many threatened and endemic birds. It also adjoins another IBA, Mukurthy NP in Tamil Nadu.
OTHER KEY FAUNA: The faunal diversity is very high and includes a number of endemic and threatened species. Some 26 species of mammals, excluding bats, rodents and insectivores, have been recorded (Balakrishnan 1984). Notable species include Nilgiri Langur Trachypithecus johni, Lion-tailed Macaque Macaca silenus, Tiger Panthera tigris, Leopard P. pardus, Jerdon’s Palm Civet Paradoxurus jerdoni, Wild Dog Cuon alpinus, Nilgiri Marten Martes gwatkinsi, Asian Elephant Elephas maximus, Gaur Bos gaurus and Nilgiri Tahr Hemitragus hylocrius, some of which are endemic to the Western Ghats. Estimates of large mammal populations are provided by Balakrishnan (1984). Six species of bats have been recorded, of which Peshwa’s bat Myotis peshwa and Hairy-winged bat Harpiocephalus harpia are considered rare. Amphibians total 19 species, lizards 9 species and snakes 11 species (Kerala Forest Department 1990). Notable records are two fishes (Holaloptera pillae and Garra menimi) and two amphibians (the primitive caecilian Ichthyophis longicephalus and Malabar tree toad Nectophryne tuberculosa).
Lepidoptera comprise about 100 species of butterflies and about 400 of moths, of which 13 are endemic to South India, and now have very restricted distributions, mostly within the Western Ghats (Mathew 1990).
BirdLife International (2019) Important Bird Areas factsheet: Silent Valley National Park. Downloaded from http://www.birdlife.org on 17/11/2019.