An isolated volcanic island in the middle of the ocean: the species that reached it evolved on their own. Several birds exist only on the slopes of this volcano.
Vegetation layers
What you cross when climbing from Mvouni. Altitudes are indicative: they vary with the slope and exposure, and the forest has retreated where it was cleared.
Low heather, everlasting flowers (Helichrysum), groundsels and lichens, then the bare lava of the caldera. Few species, but very well adapted to cold and wind.
Giant heather (Philippia comoriensis), Cussonia spicata, Brachylaena. The realm of the Karthala white-eye.
Large endemic trees, tree ferns (Cyathea), orchids, mosses and lichens. The heart of the massif’s biodiversity.
Degraded forest invaded by strawberry guava (Psidium cattleyanum), an introduced plant that prevents the forest from growing back.
Bananas, coconut palms, cassava, mango trees, cloves, vanilla: a landscape shaped by its inhabitants, where the walk starts from Mvouni (≈ 370 m).
Birds
BirdLife International recognises the massif as an Important Bird Area (14,228 ha). These four species are endemic to Grande Comore, and two of them live only on Karthala.
Otus pauliani
EndangeredFound only on Karthala. A small owl of about 20 cm without ear tufts, nocturnal, in montane forest and heather. Population estimated at about 2,000 individuals. Its call, a whistle repeated about once a second, can be heard at night.
Zosterops mouroniensis
Near ThreatenedFound only on Karthala, in the high-altitude giant heather. About 13 cm, olive back, yellow-green underparts, white ring around the eye. A major eruption could destroy much of its habitat.
Humblotia flavirostris
VulnerableEndemic to Grande Comore, in the forest on the slopes of Karthala. Population estimated at 10,000 to 19,000 individuals, declining. Threatened by forest loss, strawberry guava, and by common mynas and rats that raid its nests.
Dicrurus fuscipennis
VulnerableEndemic to Grande Comore. A large black bird of about 24 cm that feeds on fruit and large insects. Threatened by the conversion of forest into farmland.
IUCN Red List statuses as published at the time of checking; they are reassessed regularly.
Mammals and reptiles
Rousettus obliviosus
VulnerableA fruit bat of the Comoros (Grande Comore, Mohéli, Anjouan). It favours lava tubes, which are common on a young volcano like Karthala.
Phelsuma comorensis
Near ThreatenedOne of the smallest day geckos (≈ 12 cm), green with a rusty stripe, endemic to Grande Comore. Lives in trees, from about 600 m.
Furcifer cephalolepis
Least ConcernEndemic to Grande Comore, in humid areas and forests. More than 15,000 individuals were exported for the pet trade between 1994 and 2008.
The island is also home to species introduced by people, such as the tenrec, the civet, rats and the common myna. Some of them threaten the endemic birds.
Flora
The dense rainforest brings together large trees, many of them endemic to the Comoros:
Orchids, ferns, mosses and lichens grow on their trunks: in the cloud forest, the moisture of the clouds is enough to feed them.
Medicinal plants
In the Comoros, plant medicine remains the first resort for many families. A scientific review published in 2020 lists 207 species used in the archipelago, 9 of them endemic. Most grow at the foot of the volcano, in yards and fields; others come from the forest.
Aphloia theiformis · mfandrabo
A native shrub of the forests of the Comoros, Madagascar and the Mascarenes.
Plectranthus amboinicus · parovi, nyadombwe
Grown in house yards at the foot of the volcano.
Ocimum gratissimum · rule
Grown or growing wild near villages.
Ocimum americanum · sadzani
Grown in gardens.
Cymbopogon nardus · sandze
Grown in clumps in yards.
Cinnamomum verum · mdarasini
An introduced tree, planted among crops.
Cardiospermum halicacabum
A climber of forest edges and wasteland.
Bidens pilosa
A common roadside herb.
Comorian names are given in Shingazidja where known; they vary from one village and island to another.
Fresh or dried leaves are left for a few minutes in very hot water. This is the most common preparation, that of “Comorian tea”, which mixes several of these plants.
Tough leaves, bark or roots are boiled in water to extract more from them.
The leaves are crushed and placed directly on the skin, for wounds, boils or pain.
You breathe the steam of a hot decoction, head covered with a cloth, for colds or flu.
This is traditional knowledge, not medical advice. A natural plant is not harmless: researchers point out that several of the species used are toxic at certain doses. Pregnant women, children, people on medication: ask a doctor.
Nothing is picked in the National Park. The plants used every day come from gardens and markets, never from the protected forest.
During the climb, ask your guide the names of the plants you pass and what they are used for in their village.
Threats and protection
The white-eye can be seen in the high heather, early in the morning. The scops owl can be heard at night. Choose the tour that crosses these layers.
Sources checked in September 2026. Spotted a mistake or have something to add? Write to us: this page is updated as facts are checked.
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