The site is a roughly circular, calcarenitic islet in Grand Port Bay, 900 m from the south-east mainland of Mauritius. It is a remnant of a Pleistocene reef, which emerged around 30,000 years ago when the sea-level dropped, and lies in the dry zone of Mauritius, receiving around 1,400 mm of rain annually. The islet is classified as a Nature Reserve because of the presence of a dry evergreen lowland forest with a unique species composition, and an excellent opportunity for ecological restoration. Another eight islets in Grand Port Bay (near Ile aux Aigrettes) each cover less than 3 ha.
See Box and Table 2 for key species. Threatened species: Falco punctatus (used asreintroduction site for ‘East coast mountains’ IBA, MU005; one pair has bred); Columba mayeri (reintroduced since 1993, 54 birds in 1998, 19% of non-captive population). The islet is one of the most promising sites in Mauritius for marooning other native landbird species. Establishment of seabird populations is also a possibility. Other Grand Port Bay islets have a few nesting Puffinus pacificus and their importance to seabirds could increase in future, with appropriate management, although population sizes cannot be predicted.
Non-bird biodiversity: Plant communities: dry evergreen lowland forest, rich in ebonies Diospyros aigrettarum (habitat otherwise extinct, but probably typical of the eastern lowlands of Mauritius). Plant species: around 18 threatened species present, with more being introduced from mainland or other islets; several almost restricted to islet. Mammals: Pteropus niger (VU; occasional visitor). Reptiles: Gongylomorphus bojerii, Nactus coindemirensis (both endemic to Mauritian islets) on nearby islets (not Ile aux Aigrettes).
Pressure/threats to key biodiversity
Declared a Nature Reserve in 1965, but privately leased until 1975. After this, degradation (wood-cutting) accelerated until employment of local watchmen brought about improved protection in 1985. In 1987, a lease (which now extends to 2036) was granted to the Mauritius Wildlife Foundation, who have prepared a management plan. Intensive management then began, with the aim of rehabilitating a self-sustaining indigenous ecosystem. The plan includes habitat restoration and species recovery programmes (including introduction of native plant and animal species and eradication of exotics), research, training, education and ecotourism. Up to 1997, activities included removal of exotic weeds, eradication of cats and Rattus rattus, construction of nursery and lodgings for full-time wardens, introduction of two bird and 25 plant species (all native), and organization of supervised tourist visits. Threats to native ecosystems are posed by exotic plants (especially Leucaena leucocephala, Flacourtia indica and Litsea glutinosa) and animals (especially shrews Suncus murinus, five species of reptiles including the snake Lycodon aulicum, and Giant Land-Snails Achatina spp.). The management plan also emphasizes the need for vigilance against reinvasion by rats, trampling by visitors, coastline erosion and fire. Any translocated landbird populations would be vulnerable to the impact of cyclones.