Current status, distribution and abundance of the Western chimpanzee (Pan Troglodytes Verus) and other diurnal primates in the Bia-Goaso forest area, Ghana

Field investigations were undertaken from August 2009 to October 2010 to determine the status and conservation of the chimpanzee (Pan troglodytes verus) and other endangered diurnal primates in south-western Ghana. As part of field assessments, two primate surveys targeted at chimpanzees and the other endangered primates were conducted in the wet and dry seasons in the Bia-Goaso forest area. The surveys also aimed to prioritize major risk factors and establish the conservation value of individual forest management units within the cluster of forest reserves investigate the possibility of establishing corridors between reserves in the forest area. A combination of line transects sampling, satellite imagery analysis and interviews in communities were employed. Besides the chimpanzee; and two prosimian primates; Galagoides demidovii and Perodicticus potto, we confirmed the presence of four diurnal primates; Cercopithecus campbelli lowei, Cercopithecus petaurista petaurista, Colobus vellerosus, and Procolobus verus. The presence of three highly endangered primates; Cercocebus atys lunulatus, Cercopithecus diana roloway and Procolobus badius waldroni were however not detected during any of the surveys. The highest encounter of one hundred and two (102) primates was recorded in the Bia Resource Reserve (i.e. 50 in the wet season and 52 in the dry season), followed by Krokosua Hills Forest Reserve (77), Bonsam Bepo Forest Reserve (75), Subim Forest Reserve (50) and then Ayum Forest Reserve (44). Comparatively, very few primate species were recorded at Bia Tano Forest Reserve (18) and Asukese Forest Reserve (16) whilst no record of primates was made at the Bia, Goa and Abonyere Shelterbelts. Overall, Bia Resource Reserve was found to be richest and most diverse in terms of primate species. We estimated 249 chimpanzees (SE = 196.68, CV = 79.02%) for five reserves which constitute the current chimpanzee range in the v study area. Chimpanzee numbers could not be estimated for nine reserves that formed the rest of the study area because of inadequate number of nests recorded on transects. There was an average encounter rate of 0.48 monkey signs per km and 0.23 monkey groups per km of which more than 50% were polyspecific (mixed group) associations of Lowe‘s, Spot-nosed and Olive colobus. The majority (85%) of these associations were between the Lowe‘s and Spot-nosed monkeys. In all cases, there were significant differences in the distribution and density of primates between the medium and low-density strata but not between seasons. Lowe‘s monkey was the most widespread recorded primate whilst chimpanzees were the most restricted primates, found in only five of the fourteen reserves. General primate activity indicated a wider distribution in the wet season compared to the dry season. A logistic regression analysis of primate signs indicated that water availability, poaching activity and altitude accounted for a large proportion of this variation in the study area. However, water availability and poaching levels do not apply year-round and may change significantly between seasons. Poaching activity in the Goaso block of forest reserves was significantly higher than in the Bia Conservation Area (BCA). The Bia Conservation Area is the priority site for long-term conservation of the species based on the relatively larger chimpanzee community, the level of protection and the relatively low human disturbance. The Subim forest reserve offers the best possibility for conservation of chimpanzees among the Goaso complex of reserves. This is followed by Ayum, Krokosua Hills and Bonsam-Bepo forest reserves in descending order of importance. The high incidence of habitat destruction and hunting across the forest reserves need to be addressed as a matter of urgency through uncompromising law enforcement. In the face of limited resources, conservation efforts should concentrate on protecting the identified priority sites. Over the long term the vi development of corridors through the Community Resource Management Area approach is proposed to link the individual reserve units and incorporate them into a wider network of conservation area.

Source: KNUST