Many of the species found on the mountain are unique to the Comoros and four bird species are found only on the slopes of Mount Karthala: Humblot's Flycatcher, Comoro White-eye, Comoro Drongo and Karthala Scops Owl.
Asian Paradise Flycatcher | Léon Humblot | European Pied Flycatcher | Ochre-faced Tody-Flycatcher | Collared Flycatcher | Asian Brown Flycatcher | Willow Flycatcher | Tyrant flycatcher | Red-bellied Paradise Flycatcher | Alder Flycatcher | Willow flycatcher | Tickell's Blue Flycatcher ''Cyornis tickelliae | Spotted Flycatcher | Rufous-vented Paradise Flycatcher | Old World flycatcher | Narcissus Flycatcher | Humblot's Flycatcher | HMS ''Flycatcher'' | HMS Flycatcher | flycatcher | Chapin's Flycatcher | Apical Flycatcher |
The rare Mountain Gorilla (Gorilla beringei beringei) survives only in this ecoregion as do L'Hoest's Monkey and a sub-species of Hamlyn's Monkey as well as many species of butterflies, and birds including Grauer's Warblers, Chapin's Flycatchers, and the Ruwenzori Turaco.
In Madagascar, it is uncommon to the north and west coasts as well as Lake Alaotra, but also inhabits the Comoro Islands and Mayotte.
On the island of Grande Comore, Humblot founded a colonial company that oversaw the operations of several farms, plantations and processing factories for spices and perfumes.