EFFECTS OF VARIATIONS IN NUTRIENT CONTENT OF WILD FORAGE AND RAIDED CROPS ON FORAGING BEHAVIOUR OF AFRICAN ELEPHANTS (Loxodonta africana ) IN RIMOI GAME RESERVE, KENYA

Abstract

African elephants (Loxodonta Africana) are known to be crop raiders and feed on large quantities of food. They are also mixed feeders, ingesting both grass and browse in varying proportions. The elephants demonstrate distinct preference for different plant species in the ecosystem. Due to their immense body size, elephants have a key ecological role that is defined by their need for great quantities of food, water and habitat. With continuous loss of habitat, elephants are forced to extend their feeding range depending on the type and quality of available food. Decision to feed on crops outside protected areas was influenced by the nutrients in crops or vegetation outside the protected area. A survey in the conservation area was carried out to find the crop raiding situation. 311 respondents were randomly sampled from the population and snow ball sampling technique used to identify the respondents to be interviewed. Data on preference were obtained by making a systematic record of forage preferred. These data was deduced from records of plants which showed signs of recent elephant use. Debarked, browsed or grazed vegetation were picked with the use of secateurs, identified, tallied and air dried in the field. Twenty five plants were considered for laboratory analysis. Nine nutrients were analysed for, which included: Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, Copper, Manganese, Sodium and Neutral detergent fiber. Three samples of each plant were taken and the procedure of Chapman and Pratt (1961) with slight modification was used in the analysis of macro and micro nutrients, while Kejldahl procedure was used in the analysis of nitrogen. Landsat images were down loaded from the global land cover facility using path 169 and row 060. Bands 2, 3 and 4 were clipped to study the area shape file and false colour composite. The area was classified using the Anderson classification scheme based on three classes: trees, woodlands and shrubs. This was done in Arc GIS 9.3 and processed using Erdas imagine 9.2. Statistical analysis was carried out by use of descriptive, ANOVA and regression analyses. The popular form of conflict in this region arises from crop depredatin (52.4%). Results showed that maize (86.5%) was the most raided crop and the most preferred wild forage were Acacia tortilis (22.5%), Balanites aegyptiaca (14.8%), Acacia mellifera (9.6%), Zizyphus mucronata (7.5%) and Acacia brevispica (7.1%). There was significantly positive correlation (R2 >0.45, P < 0.001) between the feeding preference and level of nutrients among plant species. Landsat TM trajectories showed vegetation cover to have declined over the years (Cramer’s V = 0.3997), indicating that forage availability for elephants was most likely decrease. The major source of human elephant conflict in this region was crop depredation, while Acacia formed the bulk of forage preferred by L. african Africana. The most preferred wild forage was Acacia tortilis, though the bark had high NDF. The vegetation in the conservation area had declined between 1986 and 2006. In this region, the elephant population should be closely monitored to avoid exceeding the carrying capacity and the local authority in charge should institute measures that would encourage the local community to support elephant conservation.