EFFECTS OF HABITAT CHANGE ON FOOD AVAILABILITY AND PREFERENCE BY BLACK AND WHITE COLOBUS MONKEY (C. angolensis), AT KIBONGE FOREST ELGEYO MARAKWET COUNTY, KENYA.

Abstract

Forest disturbances by anthropogenic activities present challenges to animals and lead to feeding behavioural changes. Change of diet may be an important strategy to adjust to forest degradation. This study examines how changes in habitat, impact on feeding behaviour and food preference of folivorous Colobus angolensis, in Kibonge forest in Elgeyo- Marakwet County, Kenya. Data were collected between, July 2013 and July 2014. Observations were made on feeding behavior of two groups of C. angolensis in two regions of Kibonge forest (Mwen and Segen). Food types and plant species used as food and time taken in feeding were recorded. Amount of canopy cover and nature of disturbance were established using Global-information system (GIS) maps of between years 1976- 2016 and ground field work on 87 sampled vegetation plots each measuring, 20m x 10m. Leaf parts eaten by C. angolensis, were collected, identified and analyzed for nutrient content in the laboratory. Data obtained were analyzed using SPSS, xLSTAT and SAS-92 software’s for comparing means. Chi square tests were carried out to establish variations between regions and species. Pearson correlation showed a significant reduction of Kibonge forest size between the years 1976-2016 (n=7, r=0.0956, p< 0.001). More tree species were concentrated on altitude 2400m (χ2=610.95, df =78, p<0.001) and were generally disturbed by cutting (χ2=44.16 df =20, p<0.001) at all altitudes. There were n=21±15.71 and n=13±4.8 species of C. angolensis population in Mwen and Segen regions, respectively. The dorminant tree species in the forest were Cupressus lusitanica (3.9%), Dombeya goetzenii (24%), Prunus africana (11.3%), Croton macrostachyus (9.2%) and Macaranga kilimandascharica (6.8%). Selection ratio (S.R) was calculated for each eaten plant species in order to determine food preference (species with S.R>10). In dry season tree species preferred were Dombeya goetzenii, Nuxia congesta, and Cupressus lusitanica. In wet season were Prunus africana, Croton macrostachyus, Ficus thoninngii and Polyscias kikuyunensis. Mineral content and organic compounds in preferred food trees varied significantly between seasons (p<0.05) and among preferred food trees. There was a higher concentration of nutrients in preferred tree leaves during wet season than in dry season. Zinc levels were high in dry season (63.39ug) but Manganese concentration levels were lowest at all seasons (0.01ug). Acid Detergent fibre, Non digestible fibre, Crude Protein, Nitrogen, Zinc, Copper and Iron mineral elements varied significantly between seasons. High levels of flavonoids and alkaloids were present in the leaves of Ficus spp., Prunus africana, and Croton spp. in dry season. Cupressus spp., Dombeya spp. and Ekerbergia spp. had athracin, tannins and alkaloids during wet season but completely absent in wet season. Tree felling and burning of major colobus food trees are the major threats to C. angolensis in Kibonge forest. Afforestation, use of legislature and educating the public are possible mitigation measures.