The site comprises the central highlands of the island of Ndzuani, consisting of four main mountainous blocks. The north-western block (2,650 ha) includes the island’s highest peak (Ntingui, 1,595 m, directly above the island capital, Moutsamoudou), and the crater-lake Dzialandze, and is linked to the southern block by a ridge (c.930 m above sea-level near Dzialandze). The southern block (3,350 ha) includes Trindrini summit (1,474 m), the Forêt de Moya, the ridges of Hamjantro and Hasiaka, and the crater Dzialoutsounga. A sharp ridge (Ngani pass, 868 m) links Trindrini to the eastern block (350 ha), which is the peak and associated ridges of Habakari mountain (1,242 m). The Col de Patsi (700 m) links Ntingui to the north-eastern block (500 ha), which is the peak and associated ridges of Djadjana mountain (1,089 m).Relief is extremely precipitous, with many sharp ridges, ravines, sharply pointed summits and very steep slopes. The site contains all the remaining, scattered remnants of the island’s mixed montane forest, and also the catchments for nearly all of the coastal towns and densely inhabited inland plains (locally known as cuvettes). Forest is restricted to the steepest slopes, and resembles that of Mwali (KM003), with very large trees in places, but the abundance of orchids and pteridophytes and presence of occasional Philippia sp. is reminiscent of Karthala (on Ngazidja, KM001). In 1983, intact forest was estimated to cover 2,164 ha, with 6,118 ha underplanted, sometimes on slopes of at least 45º. Recent estimates vary, but all authorities agree that less than 2,500 ha of intact forest remained in the 1990s and the current total could be only half that, as degradation continues. The main forest areas appear to be the immediate surroundings of Ntingui and Trindrini; the Bandani, Choungoui, Gnavivi and Koundré river catchments; and the north face of Habakari. The extensive Forêt de Moya is almost totally underplanted. The main forest-use is cutting of trees for timber, charcoal manufacture and conversion for agriculture. Non-timber forest products are also harvested or hunted (birds, exotic tenrecs Tenrec ecaudatus).
Three species are endemic to Ndzuani, one of which, Otus capnodes, is threatened, though frequent in both intact and underplanted forest. Among the four other restricted-range species, Columba pollenii (uncommon in intact and underplanted forest) is Near Threatened. The near-threatened non-endemic Circus maillardi also occurs. Seven Ndzuani-endemic and eight Comoro-endemic subspecies are also present; of the former, two (Turdus bewsheri bewsheri and the rare Leptosomus discolor intermedius) are very distinctive.
Non-bird biodiversity: Evergreen forest likely to be rich in Ndzuani- and Comoro-endemic species. Mammals: Pteropus livingstonii (CR; endemic to Ndzuani and Mwali, Ndzuani population c.350–400; c.85% of global total), Rousettus obliviosus (LR/nt; Comoro-endemic species), Myotis goudoti (LR/nt; Ndzuani-endemic subspecies), Eulemur mongoz (VU; introduced, but very important population on Ndzuani). Reptiles: six Comoro-endemic species: Paroedura sanctijohannis, Phelsuma v-nigra, Amphiglossus johannae, Mabuya comorensis, Lycodryas sanctijohannis, Typhlops comorensis. Butterflies: five Ndzuani- and four Comoro-endemic species (three shared only with Mwali).
Pressure/threats to key biodiversity
The problems of overpopulation and natural-resource degradation on Ndzuani are among the worst in Africa. The forests are at present unprotected, and the severity of environmental problems would complicate the creation of reserves. The major threat to native wildlife is deforestation, which follows the same progression with the same causes as elsewhere in the Republic: underplanting (removing undergrowth and preventing regeneration) followed by clearance for treeless cultivation (see ‘General introduction’). Charcoal requirements on Ndzuani, for distillation of ylang-ylang Cananga odorata, are high: around 1990, 300 distilleries consumed 55 tonnes per year. New roads and tracks have assisted forest exploitation by easing accessibility to the forest. This virtually complete exhaustion of natural resources on Ndzuani has resulted in emigration to Mwali (KM003), bringing accelerated degradation there (see ‘General introduction’). Hunting affects pigeons, Accipiter francesiae and Otus capnodes. Exotic plant species and rats are abundant in the forest. Finally, severe cyclones are a threat to the forest habitat, perhaps more on Ndzuani than other islands because of the extreme forest fragmentation.
BirdLife International (2021) Important Bird Areas factsheet: Ndzuani highlands. Downloaded from
http://www.birdlife.org on 19/05/2021.