It covers an Area 273,300 ha with an Altitude of 1,800 - 3,000 meter. This forest complex covers a substantial area of the south-western highlands of Kenya, and probably represents the largest remaining nearcontinuous block of montane indigenous forest in East Africa. The forests cloak the western slopes, and part of the crest, of the Mau Escarpment, a block of raised land that forms the western wall of the Gregory Rift Valley, rising steeply from the floor and sloping away more gradually to the west.

There are five main Forest Reserves, Eastern, Western and South-western Mau, 66,000, 22,700 and 84,000 hactares respectively, Trans-Mara 34,400 hactares and Ol Pusimoru 17,200 hactares. The Mau has deep, fertile, volcanic soils, and rainfall in places is among the highest in Kenya. Annual precipitation ranges from 1,000 milimeters in the east, with a seasonal regime, to 2,000 milimeters in the west, where it is more-or-less continuous around the year. Numerous streams drain the forests west of the scarp crest, forming part of the Sondu and Mara river systems, which flow into Lake Victoria, and the Southern Ewaso Ngiro system, which flows into Lake Natron. The Eastern Mau is the main watershed for Lake Nakuru, through the Njoro, Makalia and Enderit rivers. The surrounding areas are intensively farmed, with human population densities about twice as high on the western side of the forest as on the east. Vegetation patterns are complex, but there is a broad altitudinal zonation from west to east, lower montane forest below 2,300 meters giving way to thickets of bamboo Arundinaria alpina mixed with forest and grassland, and finally to montane sclerophyllous forest near the escarpment crest.

The lower montane forest is in best condition in the South-western Mau Nature Reserve, where characteristic trees include Aningeria adolfi-friedericii and Strombosia scheffleri elsewhere, this zone has been heavily and destructively logged, most recently for plywood from Polyscias kikuyuensis. Logged-over areas are dominated by pioneer species such as Tabernaemontana stapfiana, Syzygium guineense and Neoboutonia macrocalyx, while pockets of less-disturbed forest hold Olea capensis, Prunus africana, Albizia gummifera and Podocarpus latifolius. Substantial parts of the high Juniperus - Podocarpus - Olea forest have been encroached and cleared, although some sections remain in good condition. Large areas of both the Eastern and Western Mau have been converted to plantation forest.

The avifauna of the forests except for the Maasai Mau is now fairly well studied. The Mau generally has a rich highland bird community, characteristic of the Central Kenya highlands but with some western affinities. A number of regional endemics occur such as Tauraco hartlaubi and the restricted-range Cisticola hunteri and Francolinus jacksoni. Regionally threatened species include Hieraaetus ayresii (scarce and local), Stephanoaetus coronatus (resident in small numbers), Tyto capensis (no recent records), Bubo capensis, Glaucidium tephronotum (fairly common), Indicator exilis, Sheppardia polioptera (uncommon and local), and Campephaga quiscalina (uncommon resident). This forest holds one of the richest examples of a central East African montane avifauna, and its size means that populations of most species are likely to be viable.