Population Size and Seasonal Distribution of the Hirola(Damaliscus Ltunteri; Sclater, 1889) in Southern Garissa, Kenya

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Addis Ababa University


The study on the population size and seasonal distribution of the Hunters' hartebeest also known as Hirota (Damaliscus hunteri; Sclater, 1889), was conducted in southern Garissa, Kenya for 6 months that included a dry and a wet season. Monthly ground counts of this species were carried out in an area of about 12,000 km2 of its natural habitat. The specific objectives of this study were to determine the current population size, its seasonal distribution, habitat preference and demographic compositions of the Hirota herds. The study showed the Hirota population in Southern Garissa consisted of about 1416 individuals. Vegetation specific observations of the Hirota individuals indicated a marked preference for less wooded vegetation and relative avoidance of the densely wooded habitats. These facts were more marked during the wet season. The chief characteristics of its preferred habitats were shrubby-grasslands with low woody canopy cover. However, habitat preferences were different for the Hirota social classes, period of season and prominent activity patterns. The Hirota distribution in the different range units was not uniform during the dry season. Relative combination of green forages, vegetation cover, livestock and human densities were the primary proximate cause of the Hirota seasonal distribution. These were largely determined by the temporal and spatial patterns of rainfall. The Hirota concentrated in ephemeral areas containing residual green forages during the dry season and dispersed randomly and uniformly when rain falls. The Hirota group structure varied seasonally and locally thus indicating differential distribution of sex and age classes. Apart from eco-climatic determinants of group sizes, other factors such as the social class and male dominance influenced the Hirota herd sizes and composition. Females constituted about 40.3% of the total Hirota observations. Relatively high proportion of young and yearling indicated a healthy growing population. The study established the main threa ts of the Hirola to be sporadic hunting, predation, and competition from livestock, expanding human settlements and bush encroachment in its key habi tats.