Nepal’s landmass of 141,181 km2 occupies the central part of the Himalayas between the Palearctic and Indomalaya ecozones. Altitude ranges from 67 m above sea level in the south-eastern Terai to 8,848 m at Sagarmatha within a short horizontal span. These extreme differences in altitude have resulted in 11 bio-climatic zones ranging from lower tropical below 500 m to nival above 5,000 m in the High Himalaya, encompassing nine terrestrial eco-regions with 36 vegetation types. Botanists recorded 1,120 species of non-flowering plants and 5,160 species of flowering plants. Nepal ranks 10th in terms of richest flowering plant diversity in Asia. Zoologists recorded 181 mammal species, 844 bird species, 100 reptile species, 43 amphibian species, 185 freshwater fish species, and 635 butterfly species. The Government of Nepal has established a network of 17 protected areas since 1973, consisting of ten national parks, three wildlife reserves, three conservation areas and one hunting reserve.