Population size, Habitat preference, feeding ecology and activity patterns of Grivet monkey (Chlorocebus aethiops) in Tumet forest, Homosha district, Assosa zone, western Ethiopia

Grivet monkeys are mostly herbivorous and feed on a wide range of food items. The study was conducted in two seasons from February to August 2024 to identify grivet monkey habitat preferences, population size, feeding ecology, and activity patterns. The stratified random sampling design was used for line transect to study population size and habitat preferences of the grivet monkey while instantaneous scan sampling design was used to study behavioral activity and feeding ecology of grivet monkey in the study area. A total of 260 grivet in dry season and 225 in wet season were counted in five study sites. Of which the highest number was accounted by adult females 90(34.6%) in dry and 80(35.6%) in wet season followed juveniles 70(26.9%) in dry season and 60(26.6%) in wet seasons. Ficus sure (29.9%) was the most frequently consumed followed, Ficus vasta (17.5%), Syzygium guineense (15.1%). On the other hand, Syzygium guineense comprised the highest (22%) followed by Oxytenanthera abyssinica (20%), and F. vasta (16.5%) was consumed during the wet season. Their proportion of feeding on fruit was 65.06% (dry) and 54.85% (wet); leaves 15.31% (wet) and 6.02% (dry); insects 14.13% (dry) and 8.46% (wet); flowers 1.77% (wet) and 1.5% (dry) and they consumed 13.31% (dry) and 19.71% (wet) on other unidentified items. The percentage of activity time budget observed on feeding was 33.77% (dry) and 25.89% (wet); resting 22.21% (wet) and 30.48% (dry); moving 23.78% (dry) and 27.92% (wet); grooming 10.12% (wet) and 7.24% (dry); playing 3.15% (dry) and 9.40% (wet) and they spent 1.59% and 4.46% of their behavioral activity on other social activities during the dry and wet season, respectively. The main threats to grivet in the study area; selective logging, habitat loss and degradation and also extensive agricultural expansion. Therefore, it is essential to local and regional governments with local communities emphasis on protecting and replanting in and around all habitat types.