Sinharaja is the country is last viable area of primary tropical rainforest. Sinharaja Forest Reserve meaning ‘Lion Kingdom’ is the best known Rain Forest in the country and has been identified as important biodiversity hotspot. The most significant geological feature of Sinharaja is the presence of a "Sinharaja Basic Zone" which comprises hornblende pyroclasts, basic charnockites pyroxene amphibolites and scapolite. 73 native species have so far been identified in Sinharaja Rainforest, including birds, butterflies, fish, mammals, reptiles and amphibians, making it a world-famous hotspot for biodiversity. Sinharaja has recorded over 154 species of birds and is known to have a ‘mixed-species feeding flocks’ or informally called a ‘bird wave’ where two or more species feed and move together.