Current view: Text account
Site description (2001 baseline):
Site location and context
Plaine des Roches is a flat area of young lava, with many caves (lava tubes) in the hot, dry lowlands of the north-east coast of Mauritius. The volcanic rock is poorly weathered and the ground extremely boulder-strewn, making the area difficult to cultivate. Most of the plain supports scrubby exotic vegetation, mostly stunted
Eucalyptus tereticornis. However, one portion covering 260 ha—State Land Bras d’Eau—includes 160 ha of other exotic plantation species (in addition to 100 ha of
Eucalyptus), which are taller and more shade-bearing, and include several species rarely planted away from this site. These species are planted in blocks of a few hectares, most of which are dominated by one tree species. The commonest are two
Araucaria species, but other broadleaved species include
Tabebuia pallida,
Swietenia mahagoni,
Cordia alliodora,
Cassia fistula and fruit trees, especially mango
Mangifera indica. Most of the Plaine supports few, if any, human uses. State Land Bras d’Eau is managed by the Forest Service as a plantation.
See Box and Table 2 for key species. The Plaine des Roches is by far the most important site on Mauritius for the restricted-range species
Terpsiphone bourbonnensis (Mauritian endemic subspecies
desolata). Other
desolata populations may have declined by 50% over the last 20 years, but the population on the Plaine des Roches appears not to have changed (c.78 pairs, 30–90% of population, 1993). This population is restricted to the 160 ha of shade-bearing exotics at Bras d’Eau. The area is also very important for the cave-nesting
Collocalia francica (at least 17 colonies of less than 50 nests each, in lava tubes, 1990s).
Non-bird biodiversity: Little native wildlife occurs. Native plant communities: dry evergreen thicket of littoral zone (less disturbed than usual on Mauritius); fresh or brackish water pools (rare, poorly known habitat). Reptiles: Phelsuma cepediana (endemic). Mammals: Mormopterus acetabulosus (VU).
Pressure/threats to key biodiversity
No reserve exists, but management of Bras d’Eau by the Forestry Service takes full account of its importance to
Terpsiphone bourbonnensis. The key to the importance of Bras d’Eau for
Terpsiphone bourbonnensis may be the habitat structure, a scarcity of introduced nest-predators such as
Macaca fascicularis, and abundance of mosquitoes.
Collocalia nesting caves around the town of Roches Noires suffer continuing disturbance, including clothes-washing, gambling, vandalism and black-magic ceremonies. Plans for a new international airport on the Plaine des Roches have been aired, but the plan appears to have been abandoned.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Plaine des Roches - Bras d'Eau (Mauritius). Downloaded from
https://datazone.birdlife.org/site/factsheet/plaine-des-roches--bras-deau-iba-mauritius on 23/11/2024.
