Population Status, Diets, Activity Budget and Range Use By Arsi Gelada (Theropithecus Gelada Arsi) In Eastern Arsi, Ethiopia
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Date
2019-01-01
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Addis Ababa University
Abstract
Population Status, Diets, Activity Budget and Range Used by the Arsi Gelada (Theropithecus gelada arsi) in Eastern Arsi, Ethiopia
Amera Moges Gebeyehu
Addis Ababa University
January 2019
Geladas (Theropithecus gelada arsi) are robust terrestrial primates endemic to Ethiopian highlands containing two known (T.g.gelada and T.g.obscurus) subspecies and the possible third subspecies, the T.g.arsi. Arsi gelada is an isolated population found in eastern Arsi, southeast of the Rift Valley. Knowledge of the population status and behavioral ecology of the species are crucial to design conservation and management plans. The aim of study was to assess the population size, distribution patterns and behavior of the gelada in eastern Arsi around Goro-Jena villages. Above ground grass biomass and phenological pattern were assessed to investigate temporal changes in food availability. Total count was used to investigate the population size of gelada. The activity budget, feeding ecology and range used by Arsi geladas were carried out using scan sampling method at 30-minute intervals from the selected focal group in a band. Ranging ecology data were analysed with a combination of ArcGIS and Home Range Tools. Home range was estimated using fixed Kernel Density Estimation and Minimum Convex Polygon. Habitat use of geladas was assessed. A mean total of 1315±11.3 individuals were recorded. Arsi geladas occurred in patchy distribution. They comprised an average unit size of 9.42±3.31and 11.43±3.95 individuals, and 26.04 and 31.19 individuals per band during the wet and dry seasons, respectively. Geladas spent the highest time in feeding (57.29%±5.04) and socializing (18.64%±3.80). Diurnal cyclic activities start early in the morning until dusk. Socializing and resting was peak early in the morning. Feeding peaked late in the morning and afternoon. The gelada diet is composed of graminoids (83.33%). Digitaria abyssinica was the most preferred species. Geladas utilized the highest (51.87%±15.87) frequency on open grazing plains and escarpment/cliffs (47.64%±16.16). The overall home range size of geladas is 134 ha using 95% KDE. Geladas traveled a mean daily path length of 1439.7 m ± 494.68. Greenness and grass biomass were significantly correlated with monthly rainfall. The overall graminoid production was estimated with a mean wet weight of 197.1±110.8 g/m2 and dry-weight of 98.8±47.7 g/m2. Activity budget of geladas showed significant difference across months (ANOVA, P < 0.001). However, there were insignificant variations among activities of feeding (P = 0.548), socializing (P = 0.356) and resting (p = 0.708) during the wet and dry seasons. Moving showed significant difference (P = 0.034) between the two seasons. Feeding time of Arsi geladas was high during both the wet and dry seasons due to lower quality and availability of diet in lower elevation and marginal habitat. Gelada fed on brown yellow grasses during dry season. Seasonal variations and warmer weather conditions contributed a lot for shifting food items and activity budgets. Arsi geladas are highly threatened due to warmer weather condition and high anthropogenic activities. Thus, conservation managers should do more to ensure the long-term survival of this unique, little is known about gelada in its narrow and human dominated landscape in Eastern Arsi. Further, researches on Arsi gelada including its nutritional requirement, gastrointestinal parasitic ecology and conflict with human are crucial to design conservation strategy.
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Activity Budget, Arsi Gelada, Feeding Behavior, Graminoids, Home Range, Population Status