Zanzibar is an insular autonomous region of Tanzania. It is composed of the Zanzibar Archipelago in the Indian Ocean, 25–50 kilometres off the coast of the mainland, and consists of many small islands and two large ones: Unguja and Pemba Island.
The main island of Zanzibar, Unguja, has a fauna reflecting its connection to the African mainland during the last Ice Age. Endemic mammals with continental relatives include the Zanzibar red colobus, one of Africa's rarest primates, with perhaps only 1,500 existing. Isolated on this island for at least 1,000 years, this colobus is recognized as a distinct species, with different coat patterns, calls, and food habits from related colobus species on the mainland. The Zanzibar red colobus lives in a wide variety of drier areas of coastal thickets and coral rag scrub, as well as mangrove swamps and agricultural areas. About one third of them live in and around Jozani Forest. The easiest place to see the colobus is farmland adjacent to the reserve. They are accustomed to people and the low vegetation means they come close to the ground. Rare native animals include the Zanzibar leopard, which is critically endangered, and the recently described Zanzibar servaline genet. There are no large wild animals in Unguja. Forested areas such as Jozani are inhabited by monkeys, bushpigs, small antelopes, African palm civets, and, as shown by a camera trap in June 2018, the elusive leopard. Various species of mongoose can also be found on the island. There is a wide variety of birdlife and a large number of butterflies in rural areas.