The Comoro Islands are situated in the western Indian Ocean in the northern part of the Mozambique Channel, equidistant from continental Africa and Madagascar. Three islands-Grand Comoro (or Ngazidja, 1,148 km²), Moheli (Mwali, 290 km²) and Anjouan (Ndzuani, 424 km²)-constitute the independent republic of the Comoros, and one island-Mayotte (Maore, 370 km²)-is a French collectivité territoriale. The highest point is Mt Karthala, an active volcano in the south of Grand Comoro.

The native vegetation on the islands is evergreen forest, with the forest on Mt Karthala naturally occurring up to c.1,800 m, above which giant-heath vegetation, with stands of Philippia, predominates.

All the restricted-range species occur in forest, largely in the uplands (where there is forest remaining), apart from Zosterops mouroniensis which is now confined to the higher-altitude heath zone of Mt Karthala on Grand Comoro. Colonizing ('pioneer') forest on recent lava-flows on this mountain may be an important habitat for some species, e.g. Otus pauliani, and, on Mayotte, mangroves may be an alternative habitat for some forest birds (Louette 1988a,b, Louette et al. 1988, 1993, Herremans et al. 1991, Louette and Stevens 1992).

The distribution of species across the islands is not uniform, with each island having its own endemic species (five on Grand Comoro, one on Moheli, three on Anjouan, and three on Mayotte). Mt Karthala is the most important area ornithologically, four species being restricted to this one mountain alone; all the other multi-island, restricted-range species as well as Nesillas brevicaudata (which occurs more widely on Grand Comoro) also have significant populations there, further emphasizing its importance.

Another restricted-range species which occurs on the Comoros (and possibly breeds) is Madagascar Heron Ardea humbloti (see EBA 096).

Today, forest has been largely cleared from the lowlands and grazing by cattle prevents regeneration; on Mt Karthala cultivation now extends as high as 1,400 m in places. Very little intact, upland forest remains on Anjouan, while most that exists on Moheli and Grand Comoro is badly degraded. On the other hand, the pioneer forest on Mt Karthala is not (yet) exploited (being marginal for agriculture) and could therefore play an important role for bird conservation on Grand Comoro (Stevens et al. 1995).

The four species restricted to Mt Karthala are considered threatened, and, consequently, the forests here rank highly amongst the key forests for threatened birds in Africa (Collar and Stuart 1988). Further habitat degradation and fragmentation (from fires, logging and as a result of a proposed road to the crater rim) in this region are particularly threatening to Zosterops mouroniensis (confined to the heath zone) and Otus pauliani (wetter north, west and south flanks). Although Dicrurus fuscipennis was judged to number c.100 birds in 1985, it appears to prefer forest edge and is probably at no immediate risk.

On Anjouan, the recently rediscovered Otus capnodes (found in 1992 after an absence of records dating back to 1886), confined to c.10 km² of native forest (i.e. all that remains), is estimated to number just 48 birds; accelerating habitat clearance and capture for food render it highly threatened (Moorcroft 1996, Safford 1993b). On Mayotte, Dicrurus waldenii lives at low density (the entire population may not exceed a few dozen pairs); protection of the forests on Mts Sapéré, Bénara and Choungi has been proposed (Louette 1988b). Reserves have also been proposed on Mt Karthala, on Moheli (Louette and Stevens 1992), and on Anjouan (Moorcroft 1996).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Comoro Islands. Downloaded from https://datazone.birdlife.org/eba/factsheet/108 on 23/11/2024.