Population structure and distribution of geladas (Theropithicus gelada, Ruppell1835) in Kotu Forest, Northern Ethiopia

Abstract

The populations of the endemic gelada outside protected areas are less studied and population estimates are not available. As a result, a study was conducted to investigate population structure and distribution of geladas in Kotu forest and associated grasslands, in Northern Ethiopia. The study area was stratified into five habitats namely; grassland, wooded grassland, plantation forest, natural forest and bushland based on dominant vegetation type. Each habitat type was further divided into blocks and total counting technique was employed to count the individuals of geladas. The total mean number of gelada in the Kotu forest was 229 ± 6.11. The mean ratio of male to female was 1:1.178. Age composition of geladas comprised: 113 (49.34%) adults, 77 (33.62%) sub adults and 39 (17.03%) juveniles. The mean group size of gelada was 18± 2.0, out of which 2.5± 0.5 (13.89%) was all- male unit (AMU) and 15.5± 1.5 (86.11%) was one male unit (OMU) social system. The average band size was 45.0± 2.53. The highest number of geladas was recorded from grassland habitat 68 (29.87%) and the lowest from plantation forest habitat 34 (14.74%). Even though, the sex ratio was female biased, the proportion of juveniles to other age classes was very low, indicating negative consequences for the future viability of the gelada populations in the area. Geladas were widely distributed over open grassland habitat. For sustainable conservation of the geladas in the area there is a need for integrated management of the area with special attention on the conservation of the grassland habitat.