Global Ecology and Conservation (Apr 2022)
Dietary ecology of the southern gelada (Theropithecus gelada obscurus) living in an Afroalpine ecosystem of the Borena Sayint National Park, Wollo, Ethiopia
Abstract
Primates show dietary flexibility as a result of spatial and temporal variation in the food availability which in turn influences the ecology of a species. Southern geladas (Theropithecus gelada obscurus) are endemic subspecies of gelada that inhabit in north central Ethiopian Highlands. During the 18 months of the first intensive study period, we examined the feeding ecology of southern geladas and their dietary responses to seasonal variations in an Afroalpine ecosystem, Borena Sayint National Park, an important site for the conservation of biodiversity in the north central Ethiopia. We collected monthly diet data from a band of southern geladas using instantaneous scan sampling method, and monthly temporal changes in green graminoid leaves and/or forb availability data using visual inspection from the randomly selected plots. The overall diet of southern geladas at Keywasha consisted of 54.4% graminoid leaves, 9.4% graminoid underground, 9.0% graminoid seeds, 17.0% forb leaves, 7.4% forb underground and 1.5% invertebrates. The diet of geladas exhibited wide variability across months. Southern geladas spent significantly more time feeding on the graminoid leaves, and significantly less time on the graminoid and forb underground diet items during the wet season than the dry season. Graminoid leaf consumption was significantly positively correlated with monthly increment of green graminoid leaf availability. By contrast, there was a significant increase in the consumption of graminoid underground when monthly green graminoid leaf availability becomes low. The result shows that southern geladas adapt seasonal shifts in their diet consumption as staple foods changed temporally in the Ethiopian Afroalpine ecosystem. Our findings contribute to a better understanding of the dietary flexibility of primates in response to local environment conditions that may shape primate ecology and evolution.
