Sao Tome and Principe

São Tomé and Príncipe comprise an island nation off the central coast of Western Africa. Most of its terrain is mountainous, and the two primary islands were formed by now-extinct volcanoes. Most of the country is used for human activities, in its majority by irrigated agriculture. São Tomé and Príncipe has high biodiversity rarity of terrestrial land vertebrates at a global scale. When analysed as single taxons, the rarity of amphibians, birds, mammals and reptiles is also high. The rarity of marine fish and mammals is also high. Challenges to biodiversity include deforestation; soil erosion; and inadequate sewage treatment.