Pemba lies 55 km east of the African mainland, from which it is separated by the Pemba Channel, in excess of 800 m deep. Pemba is essentially an oceanic island, having been isolated from mainland Africa for at least one million years. This isolation is reflected in its avifauna and the presence of an endemic bat closely related to similar species on other islands in the Indian Ocean. Pemba is administered from Unguja (the main island of Zanzibar), 35 km to the south-west. The island is indented on all sides, with numerous offshore islands, many large enough to be inhabited. It is a low island, but has numerous low, rolling hills and associated valleys in central and western areas. There is a thin strip of coral-rag habitat along the eastern edge of the island, containing some natural vegetation, but there are only two small patches of forest, totalling less than 800 ha: Ngezi in the north-west and Mwita Mkuu in the north-east. There are also considerable ‘forests’ of mangroves in the protected creeks and extensive areas of open mudflats at low tides. The rainfall generally exceeds 1,300 mm per annum, with no months totally dry.
See Box and Table 2 for key species. Only 132 species are listed for the island; an indication of Pemba’s long isolation from the mainland. Apart from the four endemic species, there are two endemic races, Accipiter tachiro pembaensis and Lamprotornis corruscus vaughani. There are a few records of Ardeola idae from the 1940s, but it is likely to be only a rare visitor now. There is also one old record of Gallinago media. Treron pembaensis is widespread and locally common. In addition, there is an introduced population of Paddaoryzivora, classified as globally threatened (Vulnerable) in its native Indonesia.
Non-bird biodiversity: There are three endemic races of snake, two endemic species and three endemic races of lizard, an endemic amphibian and an endemic fruit bat Pteropus voelzkowi (CR).
Pressure/threats to key biodiversity
As an island with a long history of cultivation there is little natural vegetation left on the island. What is left is under growing pressure as the human population increases. Protection of the remaining forest areas and maintenance of a mosaic of trees within the farmed landscape are both critical to the survival of the endemic birds on the island.