Population Status, Foraging and Diurnal Activity Patterns of Oribi (Ourebia ourebi) in Senkele Swayne’s Hartebeest Sanctuary, Ethiopia

Abstract

The study on the population status, foraging behaviour and diurnal activity pattern of oribi (Ourebia ourebi) was carried out in Senkele Swayne’s Hartebeest Sanctuary from August 2005 to March 2006 during the wet and dry seasons. Direct observation on selected oribi groups was made to study activity patterns. Total count method was used in an area of 28 km². The count of oribi in the study area ranged between 45 and 57 during the wet and dry seasons, respectively. There was no significant difference between the wet and dry season count (p>0.05). The sex ratio of adult males to females was 1.00:1.26. Oribi were mostly observed as solitary or in pairs, occasionally forming small groups. Oribi distribution showed preference to grazing on short grass (Themeda triandra) in each vegetation community. The distribution of oribi during the wet and dry seasons was similar in all vegetation communities. However, the tendency of population for wider distribution increased in the Pennisetum grassland. The annual mean proportion of daylight hours spent feeding by oribi was 54.7%. Morning and evening activity peaks were most obvious during the dry season, with most animals remaining inactive during the midday and hottest hours of the day. Large number of settled human communities in and around the Sanctuary and herds of livestock were frequently observed mainly during the wet season. Overgrazing and settlement encroachment are the major factors that could affect the population status of oribi by lowering the grass quality in the Sanctuary.