Silent Valley National Park

Silent Valley National Park is a National Park in Palakkad district, Kerala, India. It is located in the Kundali Hills of the Western Ghats. It is locally known as 'Sairandhrivanam'. The park is called Silent Valley because of a perceived absence of noisy cicadas. It is a relatively small national park with an area of 89 km².

The park is one of the last representative tracts of tropical evergreen forest in India which has survived the influence of man. The park is very important to biologists and other researchers due to its rich biodiversity. New plant and animal species are being discovered here every year. Rare bird species found here include Ceylon Frogmouth, Great Indian Hornbill, and the Nilgiri Laughingthrush. The elusive and rare Lion-tailed Macaque is also found here. The mean annual rainfall is over 3000 mm.

The park became the focal point of India's s fiercest environmental debate in the late 1970s and early 1980s, when the Kerala State Electricity Board decided to build a dam across the river Kunthi which runs through the valley. Since then a long-term conservation effort has been undertaken to preserve the Silent Valley ecosystem.

This park has some of India's last remaining rainforests. These forests are home to many rare and threatened species of wildlife including King Cobra, Liontailed Macacque and Royal Bengal Tiger.

Trekking in the park requires special permits from the Kerala State Forest department.The nearest town is Mannarkkad.

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 mean annual rainfall ranges from 4500 mm in the west to around 3200 mm in the eastern side of the park. 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.