The area is a virgin tropical forest and is home to the endangered lion tailed macaque. The park got its name because the usual screeching of cicadas in jungles is absent here. There are also some 100 species of butterflies and 400 species of moths besides birds like the Ceylon Frog Mouth, The Great Indian Hornbill and the Nilgiri Laughing Thrush. The valley centres around Kunthipuzha river.