Neumann (1902) first described the Bale monkey as a new species, Cercopithecus djamdjamensis, naming it after ‘Djam-Djam’ mountain Dandelot and Prevost (1972) further described Bale monkey as Cercopithecus aethiops djamdjamensis, being a distinct form within the vervet and grivet monkey complex. A taxonomic examination was made using specimens collected from localities west of Dodola. Up to now, Bale monkeys are thought to be restricted to the forest in south-east of the country, but little information has been published about them. In the Harenna Forest, the Bale monkey was first recorded by Lernould (1988), during his mission from 1967 to 1969. Following that mission, the species remained unreported until the Harenna Forest expedition in 1986 (Hillman, 1986). This expedition recorded the Bale monkey, but the team considered it to be a Sykes monkeys, a member of the white-throated monkey cluster of the Somali species. In late 2006 and again in late 2007, preliminary censuses were undertaken in the Harenna forest to document the population size, distribution, habitat associations, and foraging behaviour of the species. The survey confirmed the Bale monkey’s presence in the Harenna forest and collected information on the geographical range of the species. A total of 163 km of transects were surveyed in three habitats, bamboo forest, bamboo-mixed forest and non-bamboo forest. A total of 204 monkeys were observed in 31 groups over an altitudinal range of 2200-3400 m asl but restricted to only bamboo and mixed-bamboo forest. Group size ranged from 2-20. A mean density of 9.6 (SE=8.8) and overall abundance of 1437 (SE=1315) were estimated. The high variability associated with these estimates is a consequence of small sample size and short sighting distance, a consequence of the terrain, climate, and dark and closed conditions in the bamboo forest. Repeated sampling of the site with a team experienced with the terrain and the species is needed to increase the reliability of the population estimates. This important baseline information is now being used to guide further monitoring and management for the species and its habitats.
The recent Bale monkey censuses were undertaken by Kumara Wakjira of the Ethiopian Wildlife Conservation Department in collaboration with the Darwin Initiative funded Harenna project, the Bale Mountains National Park, and the University of Aberdeen.