Western woolly lemur  (Avahi occidentalis)

Western woolly lemurs are medium sized lemurs that, like all indriids, are characterized by long powerful hind limbs adapted to their specialized mode of locomotion: vertical clinging and leaping (2) (3). The dense and woolly coat is pale grey on the underparts and throat and medium-grey on the upper parts, with tinges of sandy brown on the back and tail. The face is rounded and pale with a dark muzzle. Although similar in overall appearance to its eastern relative, the eastern woolly lemur (Avahi laniger), the western woolly lemur is smaller in size and much paler (2).

Restricted to fragmented areas of western and north-western Madagascar (2). The population in Bemaraha, traditionally classed as Avahi occidentalis, has recently been reclassified as a distinct species, Avahi cleesei (4).

Found in dry deciduous forests and moist forests in the Sambirano region (2). Predominantly arboreal, most often found in the canopy (5).

The basic social group of the western woolly lemur consists of a monogamous breeding pair and their offspring (2) (5). A single offspring is usually born between September and October after a gestation period of 120 to 150 days, and juveniles may remain with their natal group until up to two years of age (2) (5). Family units occupy overlapping home ranges of two hectares and territories are defended and demarcated via calls (2).

Almost exclusively nocturnal, the western woolly lemur becomes active around dusk. The family unit largely stays together while foraging. The bulk of the diet consists of young leaves and buds taken from at least 20 different plant species (2). This folivorous diet is, however, highly specialized, including tree species that are relatively rare (6).

15 species of lemur have become extinct since sea-faring humans arrived on Madagascar's shores around 2,000 years ago, and humanity is still wreaking ecological destruction on the island (7). Habitat destruction through forest felling and burning poses the principle threat to the biodiversity on Madagascar, including the western woolly lemur (2). Small-scale but widespread clearing of forests is conducted for firewood, cattle grazing, charcoal production, and construction materials. In the dry season people often set brush fires to clear pasture for cattle but the fires frequently burn out of control and threaten protected areas (8). Hunting also occurs in some regions. These factors, coupled with the species' restricted range, give cause for concern (2).

The western woolly lemur is confirmed in only two protected areas, Ankarafantsika Nature Reserve and Manongarivo Special Reserve, although this species has also been reported in Ankarana Special Reserve (2) (4). It has so far been impossible to keep western woolly monkeys in captivity, probably because of their highly selective folivorous diet. It appears, therefore, that conservation of forests in situ where this species occurs is the best viable option of protecting the western woolly lemur (6).

For further information on the western woolly lemur see:

Garbutt, N. (1999) Mammals of Madagascar. Pica Press, Sussex.

The Primata:
http://www.theprimata.com/factsheets.html

Authenticated (14/11/2005) by Matt Richardson, independent primatologist and writer.