This EBA corresponds to the so-called Eastern and Sambirano Domains, and also includes part of the Central Mountain Domain of the Eastern Malagasy Region of Madagascar (biogeographic regions identified by White 1983). The Sambirano Domain, at the northern end of the central mountain ranges, embraces the Tsaratanana Massif and Mt Maromokotra, at 2,876 m the highest point in the EBA. Rainfall is high in this region and, there being little seasonal variation in climate, the characteristic vegetation is evergreen rain forest. The Montagne d'Ambre Massif in the far north also has rain forest and is included within this EBA.

The western boundary of the EBA has been drawn to include all the main areas of remaining rain forest, largely lying between Vohimarina in the north and Tolanaro in the south, based on satellite imagery of the vegetation taken between 1972 and 1979, these data being simplified and interpreted by Du Puy and Moat (1996) from Faramalala (1988, 1995).

The forest can be divided into three main categories: low-altitude evergreen rain forest (c.0-800 m, with some reduction in the upper limit probable towards the south of the island); mid-altitude evergreen rain forest (c.800-1,800 m), where the canopy is lower and epiphytes are common (called 'moist montane' by White 1983); and montane evergreen forest (c.1,800–2,000 m). Montane scrubland occurs at the highest altitudes (Du Puy and Moat 1996).

Madagascar is well known for its very distinct avifauna, and this EBA is particularly unusual in having nine monospecific endemic genera with restricted-range species only: Brachypteracias, Eutriorchis, Oriolia, Euryceros, Hypositta, Hartertula, Crossleyia, Dromaeocercus and Cryptosylvicola.

The restricted-range species all occur in forest and can be divided into two main groups: 12 species which are largely confined to low-altitude forest (rare or absent above 1,000 m), and eight species which are largely confined to mid-altitude and montane forest (rare or absent below 800 m); of the three remaining species, one occurs in montane scrubland (but is expected to occur in rain forest too), one apparently shows no altitudinal preference and the other has uncertain preferences (see 'Habitat associations' table).

Three species appear to be restricted entirely to the northern half of this EBA (Coua serriana, Oriolia bernieri and Euryceros prevostii); on the other hand, Xenopirostris polleni is rarer in this region than in other parts of the EBA. Ornithological exploration is, however, still incomplete and some species are proving to be more widespread than once thought: for example, Newtonia fanovanae was known only from the type-specimen collected in 1931 in Fanovana Forest (now cleared) in east-central Madagascar until its rediscovery in the reserves of Andohahela in 1989 and Ambatovaky in 1990, with sites on the Masoala peninsula and elsewhere being subsequently added. Still more dramatically, the discovery in 1992 of a new genus of passerine, Cryptosylvicola randrianasoloi, subsequently revealed to have a relatively broad distribution in the eastern rain forests, indicates that much still remains to be learned about the avifauna of Madagascar (Goodman et al. 1996). Breeding populations of Monticola bensoni (previously though to be endemic to the Isalo massif, Secondary Area s049) have recently been located in the high mountain zone of the Andringitra Strict Nature Reserve west to Ankazoabo in the West Malagasy dry forests (EBA 093) (S. M. Goodman in litt. 1996). A new species of vanga, Hypositta perdita, collected in 1931 from near Tolanaro, has recently been described (Peters 1996) and may represent another (possibly extinct) restricted-range species from this EBA.

Two other restricted-range species are shared with the West Malagasy dry forests (EBA 093), Coua coquereli and Philepitta schlegeli; both occur in the present EBA only in the Sambirano Domain. Another restricted-range species, White-breasted Mesite Mesitornis variegata, is known from one anomalous record in this EBA but is treated as being endemic to the West Malagasy dry forests (EBA 093).

An additional 16 species which occur widely in the EBA and at most altitudes, and are largely endemic to it, are not considered to have restricted ranges. These include species in a further four endemic genera-Mystacornis, Randia, Pseudobias and Oxylabes.

Figures for the extent of surviving tree cover in the east of Madagascar vary. There is an estimate that only 38,000 km² of forest remained in 1985, while reports from Sambirano indicated that the forests of that region did not exceed 400 km², and that they were fragmented and rapidly decreasing in size (Sayer et al. 1992; see also Nelson and Horning 1993). Du Puy and Moat (1996), however, calculate that there still remains 30,000-35,000 km² of low-altitude forest and the same amount of mid-altitude forest. Whatever the exact figures, secondary vegetation, largely grassland and savanna, is now widely distributed, and the eastern forests have been much reduced in historical times.

The principal threat is slash-and-burn ('tavy') cultivation by subsistence farmers, which results in progressively more degraded regrowth, turning land ultimately into grassland or bracken-covered areas. By far the biggest part of the coastal plain has either been cleared of forest or has now only highly degraded forest, and any remaining habitat is highly threatened owing to increasing pressure from the human population (Jenkins 1987). Commercial timber exploitation is an additional threat in some areas (A. F. A. Hawkins in litt. 1995) and, if current trends continue, it is likely that virtually all remaining native forest, particularly in the lowlands, will be destroyed within decades.

The majority of the restricted-range species are classified as threatened on account of their small ranges and populations, which are presumed to continue to decline with loss of habitat. However, the protected areas here do provide fairly good protection of the forest environment overall (Nicoll and Langrand 1989), and the present EBA has within it three national parks, one biosphere reserve and several strict nature and special reserves, areas which amount to some 5% of remaining low-altitude forest, 10% of mid-altitude forest and 9% of montane forest, although the amount of low-altitude forest below 600 m which is well protected is very much less (Du Puy and Moat 1996).

It is difficult to select key sites for conservation in this EBA because the known distribution of threatened species appears largely to reflect fieldwork (when new areas within the EBA are surveyed, the majority of the region’s restricted-range species tend to be found). It is nevertheless likely that the EBA's central forests will eventually turn out to be the most important. Zahamena Strict Nature Reserve, Ambatovaky Special Reserve (see Thompson and Evans 1992), Masoala Natural Park and Marojejy Strict Nature Reserve (see Evans et al. 1992a) all have significant areas of lowland forest (the most threatened habitat in this EBA) and are thus very important (A. F. A. Hawkins in litt. 1995, verbally 1997; see also Collar et al. 1987, Collar and Stuart 1988, Thorstrom and Watson 1997).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: East Malagasy wet forests. Downloaded from https://datazone.birdlife.org/eba/factsheet/110 on 22/11/2024.