Population estimate and social organization of the Southern Gelada (Theropithecus gelada obscurus, Heuglin 1863) in Abune Yosef Zigit community conservation area, North Wollo, Ethiopia

Abstract A global, accurate estimation of the Southern Gelada ( Theropithecus gelada obscurus , Heuglin 1863) population is poorly available. This study aimed to investigate the population size and structure of the Southern Gelada in the Abune Yosef Zigit Community Conservation Area. Population counts were done at six counting blocks covering both the dry and wet seasons in 2021. The total mean population size of the Southern Gelada in Abune Yosef Zigit Community Conservation Area was 929 (±8.46). The population comprised 9% (82±0.92) adult males, 34% (314±3.47) adult females, 11% (99±1.23) sub-adult males, 10% (95±1.30) sub-adult females, 24% (128±1.92) juveniles, and 13% (121±1.73) infants. However, all age groups of Southern Gelada showed insignificant seasonal variation in abundance, except for infants ( P = 0.027). The mean age and sex ratio of males to females ( χ ² = 89.97, P ≤ 0.05), adult males to adult females (1:4.18, χ ² = 135.92, P ≤ 0.05), and infants to adult females (1:3.04, χ ² = 85.63, P ≤ 0.05), varied significantly between seasons. These age and sex ratios also exhibited notable differences between the dry and wet seasons in the area ( P ≤ 0.05). Geladas exist in social groups ranging from the basic all-male unit (10.37±1.04) to complicated social bands (157.58±5.84). The population estimate is crucial and contributes to an accurate global population estimate and, consequently, better conservation of the species.