6 Jul 2012

Forest discovery improves prospects for Angola’s endemics

By Martin Fowlie

A large tract of near-pristine Afromontane forest has been found in Angola’s Namba Mountains, tripling the amount of this habitat that was thought to survive in Angola. The site meets the criteria for a new Important Bird Area (IBA), holding one globally threatened species, and assemblages of restricted range and biome-restricted bird species. Afromontane forest is the most localised and threatened habitat type in Angola. By the early 1970s, only 200 ha was estimated to remain, mainly at the Mount Moco IBA (85 ha), and perhaps in the Namba Mountains, where most forest was thought to be degraded by logging. Mount Moco and the Namba Mountains lie within the Western Angola Endemic Bird Area, which includes four restricted-range species associated with Afromontane vegetation.

Two Afromontane endemics of global conservation concern, Endangered Swierstra’s Francolin Pternistis swierstrai and Near Threatened Angola Cave-chat Xenocopsychus ansorgei, are found at Mount Moco, but the francolin is now uncommon there. The Data Deficient endemic Grimwood’s Longclaw Macronyx grimwoodi is also found at Moco. Several other Afromontane specialists have been found only there or at one or two other sites in Angola, and face a serious threat of extirpation from the country. Angola’s Afromontane forest and thicket holds 20 species, subspecies or populations of conservation significance, isolated and distinct from other Afromontane “centres of endemism”, the nearest of which is over 2000 km away. All 20 were recorded at Moco prior to 1970, but several are now rare or absent.

A team including members of the University of Jos, Nigeria, and Percy FitzPatrick Institute of African Ornithology, South Africa, travelled to the Namba Mountains in July 2010, to establish the extent and condition of forest, and to conduct bird surveys. Due to the difficulty of traversing the terrain (dense undergrowth, steep slopes, an abundance of large boulders, and limited trail access) they were confined to exploring a single forest patch and surrounding grasslands and mountain slopes, an area of 24 ha. They recorded 89 bird species, 56 of them in or adjacent to forest, including a significant population of Swierstra’s Francolin, and the other Afromontane specialists that are now hard to find at Mount Moco. On their return, they examined satellite images from Google Earth, which indicated that there is currently around 590 ha of forest in the Namba mountains, more than trebling the previous national estimate.

“Compared with the forest at Moco, individual forest patches in the Nambas are larger and have greater area/edge ratios, making these patches less susceptible to edge effects and human impacts”, the discovery team writes in their paper. Their paper, The Namba mountains: new hope for Afromontane forest birds in Angola published in BirdLife International’s journal, Bird Conservation International. “Besides this, the forest patches in the Nambas are in better condition, showing fewer signs of human disturbance. This is likely to be a consequence of the ruggedness of the terrain, and its unsuitability for establishment of human communities.” But they add: “Despite the limited extent of Afromontane forest in Angola, threats to it from human activities and its high biodiversity value, none of it is formally protected, putting it at risk of becoming the first Afromontane centre of endemism to be lost... The Nambas deserve national and international recognition for their conservation importance, and along with Moco are among the highest priorities for the establishment of new conservation areas in Angola.”