Some Patterns of Population Dynamics and Distribution of Swayne's Hartebeest (Alcelaphlls Bllselaplllls Swaynel) in Senkele Swayne's Hartebeest Sanctuary
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Date
2000-01
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Addis Ababa University
Abstract
An ecological study of Swayne's haltebeest (Alcelaphlls bliselaplllls SlVaYllei), an endangered
subspecies of antelope, was made fium February 1999 to December 1999 in Senkele Swayne's
haltebeest Sanctuary (SSHS) located 300 km from Addis Ababa. Data regarding population size,
stmcture, vegetation community utilization, home range and daily activities that included both dry
and wet seasons were gathered. A direct count method was employed in estimating the population
of the hartebeest in about 28 km2 of its natural habitat.
The total estimate of Swayne's hartebeest was between 145 in the wet season and 179 in the dry
season. Classification of 142 animals in dry season and 123 animals in wet season indicated
different sex and/or age stmctures for the population. The majority of the population was largely
comprised adult and sub-adult females (52.2%) adult and sub-adult males (31.6%). The proportion
of the young constituted (16.1 %).
Herd size altered monthly. A stable sub-group unit composed of 12 animals was observed. The
maximum group size observed was 45. Hartebeest's number of groups were largest in wet season
in the open plain and smallest in dry season in woody cover.
The results of the study showed that Swayne's llaltebeest occupied the 3 vegetation communities in
the Sanctuary. Their distribution and vegetation community utilization is found to be influenced by
food availability and the presence of human and domestic animals within the Sanctuary. The
animals were observed utilizing the 3 vegetation communities in both seasons, howev;r, there wasmore utilization of the Pennisetul1l Grassland (PG) community (77.2%) in the wet season and
62.5% in the dry season.
Locating all groups during counting provided the movement and home range data of both seasons.
Minimum Convex Polygon (MCP) method was used to calculate the home range size. Seasonal
home range size varied. Wet season home range size was twice larger than that of the dry season
(16 vs 9 Jan2).
Swayne's hartebeest activity was recorded at 4 min-intervals for continuous period of 12 In' on two
consecutive days every month of the eight months of the study period. About 48.9% of the total
time was spent in feeding and about 38.6% in resting (standing and lying). There were two feeding
peaks, one in the moming and another in the aftemoon, and one resting peak in the middle of the
day.