Grand Bassin–Le Dimitile is on the southern slopes of the volcanic Piton des Neiges massif, which are now separated from the summit by the Cirque de Cilaos and consist of a south-facing escarpment incised by eight small ravines. The site extends from the south-east rim of the Cirque de Cilaos (Sommet de l’Entre-Deux, 2,350 m) down to around 550 m on the slopes above the Bras de la Plaine river near La Commune d’Entre-Deux. Most vegetation is mixed montane forest; small areas of bare rock, scree, montane shrubland or bushland and thicket are found in the higher parts, and deforested areas with exotic vegetation (including some cultivation) occur lower down.
See Box and Table 2 for key species. The site is one of the most likely to hold breeding Pterodroma aterrima, based on the fact that seven specimens have been found nearby (five recently), and some descriptions of seabirds by local people may refer to this species. Pterodroma baraui may also breed at high altitude. All of the forest-living native birds of La Réunion occur, except Coracina newtoni, along with an important population of Puffinus lherminieri. In 1997, 3–5 pairs of Circus maillardi were present.
Non-bird biodiversity: Endemic plant communities: forest, shrubland and bushland and thicket rich in endemic plants.
BirdLife International (2019) Important Bird Areas factsheet: Grand Bassin - Le Dimitile. Downloaded from http://www.birdlife.org on 18/01/2019.