Réunion, an overseas département of France in the Indian Ocean, is the largest of the Mascarene Islands (see also EBAs 102, 103), rising steeply to over 3,000 m on the Piton des Neiges (see p. 354 for map). Over 60% of its land area is above 1,000 m and the island has a remarkable relief of volcanic massifs (one still active), dissected by deep erosion ravines and cliffs.

The island was covered with forest, including dry forest on the leeward side of the island, mixed evergreen forest (the climax vegetation) and tamarin Acacia heterophylla forest (an endemic tree which may be a fire-climax vegetation related to vulcanism). Heath vegetation is extensive at higher altitudes.

All the extant restricted-range species inhabit the remaining evergreen forest; the two species of Zosterops are the only native birds which have adapted to gardens. Most species are found throughout the island (but not at the lowest elevations), apart from Coracina newtoni, which has a particularly small range in the north-west on the forested plains of Chicots and d'Affouches (total area less than 16 km²); it is not clear why this species is only found in this region, although a recent study on the closely related Mauritius Cuckoo-shrike C. typica suggests that specialized diet and foraging methods may be significant in determining specific habitat requirements (Safford and Beaumont 1996).

The endemic Réunion Marsh-harrier Circus maillardi maillardi is usually considered conspecific with the Madagascar form macrosceles but is very different in its habitat requirements, calls and coloration (V. Bretagnolle and C. Attié in litt. 1993), and may justify recognition as a full species. A sighting of a small owl-like bird has recently been speculated to be a possible new species of scops-owl Otus (Renman 1995).

A further four endemic species are known from subfossils (including a night-heron, stork, sheldgoose and kestrel) with two more (a rail and an owl) shared with Mauritius (Cowles 1987). The Réunion Solitaire or White Dodo Raphus solitarius was also endemic to Réunion, but is only known from descriptions and pictures, and probably died out c.1710-1715. However, there is some evidence which suggests that the 'solitaire' described by the early travellers was not related to either Mauritius Dodo R. cucullatus or to Rodrigues Solitaire Pezophaps solitaria, but was probably an extinct endemic ibis Borbonibis latipes, also known only from subfossils (Mourer-Chauviré and Moutou 1987, Mourer-Chauviré et al. 1995).

Two seabirds are believed to be endemic breeders to Réunion: Mascarene Petrel Pterodroma aterrima is only known from four specimens collected in the nineteenth century, by three birds found dead (two in the 1970s and one in 1995) and by (at best) one sighting per year in the waters south of Réunion; Barau's Petrel P. baraui nests in burrows at high altitudes on Piton des Neiges.

Réunion is the least ecologically disturbed of the Mascarene Islands, having escaped the introductions of monkeys and mongooses, which have caused extensive damage on the other islands. However, other introduced predators such as rats and cats, and extensive hunting during the seventeenth century have resulted in the extinction of many (at least 16) bird taxa. Competitors are also well established although it is difficult to say how much these introduced birds affect native forms; the recent (1972) introduction of Red-whiskered Bulbul Pycnonotus jocosus, a nest-robber, may be serious as it has been blamed for causing heavy losses to white-eyes Zosterops, especially in Mauritius.

Key factors which threaten and determine the distribution of the restricted-range species today are deforestation (less than 40% of the island remains under native vegetation), habitat degradation through the introduction of alien plants and herbivores (resulting in the restriction of native forest to the steep sides of rivers at lower elevations), and hunting/poaching (e.g. of Hypsipetes borbonicus for the cage-bird trade); the retreat of some species from the lowlands may be also (partly) explained by the introduction of pathogens. Cyclones also cause extensive damage to habitats and their birds: one in 1980, for example, resulted in the deaths of up to 50% of the endemic birds and destroyed all nests (Cheke 1987a,b).

Coracina newtoni is the EBA's only species currently to be classified as threatened-due to its tiny range and population (120 pairs); it is at some risk from inappropriate forestry, poaching and impaired forest regeneration as a result of introduced deer, which are maintained at artificially high densities for the purposes of hunting (Cheke 1987a, N. Barré in litt. 1993). Part of its range-the Plaine des Chicots-was recognized as a being key forest for the conservation of threatened birds in tropical Africa by Collar and Stuart (1988). Tourism is a potential new threat, as St Denis, the largest city on the island, is close by and there are plans to build roads, hotels and parks, etc. (V. Bretagnolle and C. Attié in litt. 1993).

Both endemic petrels (see 'Restricted-range species', above) are classified as Critical: the breeding population of Pterodroma aterrima is estimated to be probably fewer than 20 pairs, while that of P. baraui is believed to have halved in recent years from an estimated 3,000 pairs owing to illegal, but persistently unpoliced, shooting by local people. The tiny breeding range of P. baraui makes it particularly vulnerable to any changes within the area, such as proposed road and cable-car projects. Circus maillardi maillardi (see 'Restricted-range species') numbers fewer than 50 pairs (although there may be several hundred individuals) and is also illegally shot (Bretagnolle and Attié 1991, V. Bretagnolle and C. Attié in litt. 1993, 1994, 1995, Attié and Bretagnolle in prep.).

There are two protected areas on the island but these are not large enough to protect the flora and fauna contained within them (Barré 1988), and their status is uncertain (C. Attié in litt. 1993; see also Doumenge and Renard 1989).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Réunion. Downloaded from https://datazone.birdlife.org/eba/factsheet/114 on 23/11/2024.