Originally, roan occupied fairly large areas of southern Kenya, occurring from Lake Natron to Lake Victoria and north to Mt Elgon and the Cherangani Hills. They also occurred in the Thika and Kitui area east of the Chyulu Hills. The last known refuge of the species in Kenya is the Lambwe Valley, in Ruma National Park which is situated 22km from Homa Bay close to Lake Victoria. The population is following a downward trend. The reasons for decline are unclear but could be a combination of numerous factors such as habitat fragmentation, habitat change, diseases, pressure from other species and predation.