Seasonal botanical characteristics of the diets of Grant’s (Gazella granti Brooke) and Thomson’s (Gazella Thomsoni Guenther) in the dryland habitats of south-central, Kenya

Abstract

Understanding of dietary requirements of different wildlife populations is critical in wildlife habitat conservation especially in Sub-Saharan Africa where wildlife contributes much to the National GDP of many countries. This study was conducted to determine the seasonal (wet/dry) diet profiles of Thomson’s and Grant’s gazelles (Gazella Thomson and Gazella granti) in the Athi-Kapiti savannah ecosystem of south-central Kenya. Diet composition was determined using the micro histological faecal analysis technique. Plant species in the diets were categorized into grasses, forbs and browse. Botanical compositions for diet selection by the two gazelles were generally influenced by season. Forage classes were significantly (P<0.05) associated with the two gazelles. Grant’s gazelle was a mixed feeder in the wet season and a browser in the dry season, whereas Thomson’s gazelle was a grazer during wet season and a browser in the dry season. The two gazelles had diverse diets in the wet season with Thomson’s gazelle having diverse diets in both seasons than Grant’s gazelle. The degree of dietary overlap between the two gazelles was highest during the dry season with a significant (P<0.05) Spearman’s rank-order correlation coefficient; Rn = 0.92. The results indicate that the two species are competitors during the dry season and complimentary feeders during the wet season. This implies that Wildlife Managers manning the conservation areas in the region need to consider the optimal stocking rates of the two gazelles during the dry season. The shift in dietary diversifications between the two species should be investigated further. The degrees of dietary overlap within the forage and forbs classes were highest throughout the two seasons. Therefore, key browse plants such as the Acacia spp, Grewia spp. and Balanities glabra and forbs such as Hibiscus parvifolius should be spared during bush control activities.