The site contains the major block of 1,260 ha of native forest in south-west Mauritius that lies to the north of the Black River Gorge system, together with adjacent exotic vegetation. The site includes the plateau above the gorge (Pétrin to Tamarin Falls); the gorge itself east of the Rivière Noire and Grandes Gorges river (including the ridges of Macchabé and Brise Fer); the west-facing Magenta escarpment; and Tamarin Gorge to Rempart mountain. The plateau areas are 550–660 m above sea-level, and the escarpments and gorge slope down almost to sea-level; the highest point, Rempart, reaches 777 m. Rainfall decreases from east to west, from 3,500 mm annually at Pétrin to below 1,500 mm on the coastal plain. Diverse types of native upland and lowland forest and thicket are present, together with a large expanse of exotic vegetation, especially around the entrance to the Black River Gorge. Most of the native vegetation is within the Black River Gorges National Park. Land outside the park is mainly privately-owned Mountain Reserve or leased State Land, some of which is used for deer-hunting.
See Box and Table 2 for key species. All eight threatened or near-threatened native landbird species of Mauritius are present. The site is particularly important for Columba mayeri (reintroduction programme at Brise Fer since 1987, population increasing to 98 birds in 1998, 34% of non-captive population), Psittacula eques (Macchabé–Brise Fer supports majority of wild population of 59–73 birds supplemented by reintroductions from captivity) and Coracina typica (c.90 pairs, 35% of world population, 1993). Other threatened species have less important, more localized populations here: Falco punctatus (present in all gorge, mountain and escarpment areas, minimum 31 pairs, 1998), Collocalia francica (uncommon breeder), Hypsipetes olivaceus (c.30 pairs, 10% of world population, 1993), Zosterops chloronothos (6–12 pairs, humid scrub only, 1993), Foudia rubra (5 pairs, 1993). All 10 restricted-range species occur at the site.
Non-bird biodiversity: Endemic plant communities, all rich in rare and endemic species: mixed montane forest (widespread—Brise Fer has one of the finest surviving areas); montane scrubland, bushland and thicket (Mare Longue Plateau; includes very rare heath and Pandanus marsh communities at Pétrin); dry evergreen lowland forest (Magenta escarpment to Trois Mamelles); evergreen bushland and thicket (Trois Mamelles). Reptiles: Phelsuma guimbeaui, Phelsuma rosagularis, Phelsuma cepediana (endemic), Gongylomorphus fontenayi (stronghold for this endemic). Mammals: Pteropus niger (VU), Mormopterus acetabulosus (VU).
Pressure/threats to key biodiversity
The Black River Gorges National Park expanded the previous Macchabé–Bel Ombre Nature Reserve, including most of the native vegetation in this area, and also the exotic forest of the Black River Gorges system. It does not extend far north of Brise Fer, and therefore excludes the Magenta Scarp, Trois Mamelles and Rempart. However, Cabinet Nature Reserve (18 ha) and also the privately-owned Mondrain reserve (5 ha) are in this area; both are important for plants. Part of the Magenta scarp is also a Mountain Reserve. The area is a focus for intensive research and conservation efforts. A study plot established in the 1930s by Vaughan was re-established in 1986 and has been the subject of detailed studies on the changes in the forest, especially invasion by exotics. Early work to conserve Falco punctatus and Columba mayeri was concentrated in and around the Black River Gorges and Brise Fer forest, and pioneering techniques were developed there; the effort is continuing, extended now to Psittacula eques. Several intensive wildlife management areas exist, including (from 1994–1998) the largest on Mauritius, at Brise Fer, where c.27 ha was fenced (to exclude deer and pigs), weeded (to remove exotic plants), and predators were controlled. These areas are critically important for native wildlife.
BirdLife International (2020) Important Bird Areas factsheet: Macchabé - Brise Fer forest. Downloaded from
http://www.birdlife.org on 05/07/2020.