Site description The site is located in the south-west and extends from the Binda and Quija rivers, on the west coast, to the confluence of the Ana Chaves and Io Grande rivers and the right bank of the Io Grande. The area comprises most of the lowland primary evergreen forests of the island as well as, in the centre, montane forest on the Cabumbe peak (1,403 m). The southern slopes of the Pico de São Tomé massif define the northern boundary of the site. Old secondary forest occurs near the coast, in the valleys of the Binda, São Miguel and Quija rivers, resulting from the regrowth of plantations abandoned in the late 1970s. Further inland the terrain is rugged and the ground broken and stoney, making walking difficult. The forests have not been fully surveyed botanically, but large trees include Uapaca sp. The understorey is generally open under a closed canopy, with few shrubs.
Key Biodiversity See Box and Table 2 for key species. Of the 32 bird species recorded from the area, 10 are of global conservation concern and the site is the only one known for Bostrychia bocagei, Lanius newtoni, Amaurocichla bocagii and Neospiza concolor. B. bocagei is silent and extremely secretive, making estimates of numbers difficult, while L. newtoni has been recorded regularly in the basins of the São Miguel, Xufexufe and Quija rivers and from the intervening ridges. A. bocagii is fairly common along forested riverbanks, but the status of N. concolor is unclear as there have been very few sightings. The six other species of conservation concern are more common.
Non-bird biodiversity: One of the two endemic bats, Myonycteris brachycephala (EN), is thought to occur. The endemic snake Philothamnusthomensis is also present, but little is known of other reptiles and amphibians.