The Bemaraha woolly lemur, also known as John Cleese’s avahi, is one of Madagascar’s most geographically restricted primates. First recorded by scientists in 1990 and formally described as a distinct species in 2005, they are known only from the Tsingy de Bemaraha region of western Madagascar, north of the Manambolo River. Despite decades of surveys elsewhere in western Madagascar, no confirmed populations have been found beyond this small, isolated landscape. Within the Tsingy de Bemaraha National Park, sightings have been limited to a few forest patches, including the Ankindrodro forest and the type locality near Ambalarano, at the base of the dramatic western Tsingy escarpment.

The entire known range of the Bemaraha woolly lemur covers less than 190 square miles (500 km²). This range is not only extremely small but also severely fragmented, with habitat continuing to shrink in area, extent, and quality. The northern limits of its distribution remain uncertain. Still, extensive field surveys and local interviews suggest that the species does not occur between major river systems farther north, reinforcing the idea that this species is confined to a narrow ecological pocket shaped by rivers, karst formations, and historical isolation.

Ecologically, Bemaraha woolly lemurs are strictly arboreal (tree-dwelling), inhabiting a mosaic of tropical dry and sub-humid forests, including semi-deciduous, riverine, edge, and karst-associated habitats. They are most often found near the western Tsingy precipices, within deep limestone crevasses and gorges, and along small seasonal streams and swampy areas close to the Bemaraha massif. Although elevation estimates vary slightly among studies, the species inhabits lowland forests, generally below 330 feet above sea level (100 m), with many records clustering closer to 100–300 feet (30–90 m).

Many of the forests used by the Bemaraha woolly lemur remain surprisingly green even during Madagascar’s long dry season. These areas tend to have a high proportion of evergreen trees, often representing secondary forest growth. Detailed habitat studies describe forests with dense understory and relatively tall trees, averaging about 38 feet in height (11.7 m), with some emergent trees exceeding 72 feet (22 m) and trunk girths of over 31 inches (80 cm). Such a structure provides the vertical complexity needed for the lemur’s mode of movement and offers both food and cover in an otherwise seasonally harsh environment.

Within these habitats, the species shows a clear preference for vegetation with taller canopies, larger tree diameters, and higher plant diversity than is typical of many dry deciduous forests. Dense understory vegetation appears especially important, offering concealment while foraging and protection from predators. These forests also supply the buds, young leaves, and fresh growth that form the basis of the species’ diet, particularly during seasonal transitions.

Despite its overall rarity, the Bemaraha woolly lemur presents an intriguing ecological pattern: local population densities sometimes appear higher in moderately disturbed forests than in less disturbed ones. This suggests a limited tolerance, or even short-term advantage, in certain secondary habitats.

Locals call the lemur dadintsifaky, or “grandfather of the sifaka,” for its sifaka-like size and its heavier, more ponderous build, cloaked in thick gray-brown fur. That evocative local name captures something essential about the species: a distinctive lemur shaped by a unique landscape, now confined to a shrinking forest world where geology, climate, and human pressure converge.